Feller, D; Schuchardt, Karen L.; Didier, Brett T.; Elsethagen, Todd; Sun, Lisong; Gurumoorthi, Vidhya; Chase, Jared; Li, Jun
The Basis Set Exchange (BSE) provides a web-based user interface for downloading and uploading Gaussian-type (GTO) basis sets, including effective core potentials (ECPs), from the EMSL Basis Set Library. It provides an improved user interface and capabilities over its predecessor, the EMSL Basis Set Order Form, for exploring the contents of the EMSL Basis Set Library. The popular Basis Set Order Form and underlying Basis Set Library were originally developed by Dr. David Feller and have been available from the EMSL webpages since 1994. BSE not only allows downloading of the more than 500 Basis sets in various formats; it allows users to annotate existing sets and to upload new sets. (Specialized Interface)
NASA Astrophysics Data System (ADS)
Spackman, Peter R.; Karton, Amir
2015-05-01
Coupled cluster calculations with all single and double excitations (CCSD) converge exceedingly slowly with the size of the one-particle basis set. We assess the performance of a number of approaches for obtaining CCSD correlation energies close to the complete basis-set limit in conjunction with relatively small DZ and TZ basis sets. These include global and system-dependent extrapolations based on the A + B/Lα two-point extrapolation formula, and the well-known additivity approach that uses an MP2-based basis-set-correction term. We show that the basis set convergence rate can change dramatically between different systems(e.g.it is slower for molecules with polar bonds and/or second-row elements). The system-dependent basis-set extrapolation scheme, in which unique basis-set extrapolation exponents for each system are obtained from lower-cost MP2 calculations, significantly accelerates the basis-set convergence relative to the global extrapolations. Nevertheless, we find that the simple MP2-based basis-set additivity scheme outperforms the extrapolation approaches. For example, the following root-mean-squared deviations are obtained for the 140 basis-set limit CCSD atomization energies in the W4-11 database: 9.1 (global extrapolation), 3.7 (system-dependent extrapolation), and 2.4 (additivity scheme) kJ mol-1. The CCSD energy in these approximations is obtained from basis sets of up to TZ quality and the latter two approaches require additional MP2 calculations with basis sets of up to QZ quality. We also assess the performance of the basis-set extrapolations and additivity schemes for a set of 20 basis-set limit CCSD atomization energies of larger molecules including amino acids, DNA/RNA bases, aromatic compounds, and platonic hydrocarbon cages. We obtain the following RMSDs for the above methods: 10.2 (global extrapolation), 5.7 (system-dependent extrapolation), and 2.9 (additivity scheme) kJ mol-1.
Spackman, Peter R.; Karton, Amir
2015-05-15
Coupled cluster calculations with all single and double excitations (CCSD) converge exceedingly slowly with the size of the one-particle basis set. We assess the performance of a number of approaches for obtaining CCSD correlation energies close to the complete basis-set limit in conjunction with relatively small DZ and TZ basis sets. These include global and system-dependent extrapolations based on the A + B/L{sup α} two-point extrapolation formula, and the well-known additivity approach that uses an MP2-based basis-set-correction term. We show that the basis set convergence rate can change dramatically between different systems(e.g.it is slower for molecules with polar bonds and/or second-row elements). The system-dependent basis-set extrapolation scheme, in which unique basis-set extrapolation exponents for each system are obtained from lower-cost MP2 calculations, significantly accelerates the basis-set convergence relative to the global extrapolations. Nevertheless, we find that the simple MP2-based basis-set additivity scheme outperforms the extrapolation approaches. For example, the following root-mean-squared deviations are obtained for the 140 basis-set limit CCSD atomization energies in the W4-11 database: 9.1 (global extrapolation), 3.7 (system-dependent extrapolation), and 2.4 (additivity scheme) kJ mol{sup –1}. The CCSD energy in these approximations is obtained from basis sets of up to TZ quality and the latter two approaches require additional MP2 calculations with basis sets of up to QZ quality. We also assess the performance of the basis-set extrapolations and additivity schemes for a set of 20 basis-set limit CCSD atomization energies of larger molecules including amino acids, DNA/RNA bases, aromatic compounds, and platonic hydrocarbon cages. We obtain the following RMSDs for the above methods: 10.2 (global extrapolation), 5.7 (system-dependent extrapolation), and 2.9 (additivity scheme) kJ mol{sup –1}.
Rossi, Tuomas P. Sakko, Arto; Puska, Martti J.; Lehtola, Susi; Nieminen, Risto M.
2015-03-07
We present an approach for generating local numerical basis sets of improving accuracy for first-principles nanoplasmonics simulations within time-dependent density functional theory. The method is demonstrated for copper, silver, and gold nanoparticles that are of experimental interest but computationally demanding due to the semi-core d-electrons that affect their plasmonic response. The basis sets are constructed by augmenting numerical atomic orbital basis sets by truncated Gaussian-type orbitals generated by the completeness-optimization scheme, which is applied to the photoabsorption spectra of homoatomic metal atom dimers. We obtain basis sets of improving accuracy up to the complete basis set limit and demonstrate that the performance of the basis sets transfers to simulations of larger nanoparticles and nanoalloys as well as to calculations with various exchange-correlation functionals. This work promotes the use of the local basis set approach of controllable accuracy in first-principles nanoplasmonics simulations and beyond.
Rossi, Tuomas P; Lehtola, Susi; Sakko, Arto; Puska, Martti J; Nieminen, Risto M
2015-03-01
We present an approach for generating local numerical basis sets of improving accuracy for first-principles nanoplasmonics simulations within time-dependent density functional theory. The method is demonstrated for copper, silver, and gold nanoparticles that are of experimental interest but computationally demanding due to the semi-core d-electrons that affect their plasmonic response. The basis sets are constructed by augmenting numerical atomic orbital basis sets by truncated Gaussian-type orbitals generated by the completeness-optimization scheme, which is applied to the photoabsorption spectra of homoatomic metal atom dimers. We obtain basis sets of improving accuracy up to the complete basis set limit and demonstrate that the performance of the basis sets transfers to simulations of larger nanoparticles and nanoalloys as well as to calculations with various exchange-correlation functionals. This work promotes the use of the local basis set approach of controllable accuracy in first-principles nanoplasmonics simulations and beyond. PMID:25747068
Accurate basis set truncation for wavefunction embedding
NASA Astrophysics Data System (ADS)
Barnes, Taylor A.; Goodpaster, Jason D.; Manby, Frederick R.; Miller, Thomas F.
2013-07-01
Density functional theory (DFT) provides a formally exact framework for performing embedded subsystem electronic structure calculations, including DFT-in-DFT and wavefunction theory-in-DFT descriptions. In the interest of efficiency, it is desirable to truncate the atomic orbital basis set in which the subsystem calculation is performed, thus avoiding high-order scaling with respect to the size of the MO virtual space. In this study, we extend a recently introduced projection-based embedding method [F. R. Manby, M. Stella, J. D. Goodpaster, and T. F. Miller III, J. Chem. Theory Comput. 8, 2564 (2012)], 10.1021/ct300544e to allow for the systematic and accurate truncation of the embedded subsystem basis set. The approach is applied to both covalently and non-covalently bound test cases, including water clusters and polypeptide chains, and it is demonstrated that errors associated with basis set truncation are controllable to well within chemical accuracy. Furthermore, we show that this approach allows for switching between accurate projection-based embedding and DFT embedding with approximate kinetic energy (KE) functionals; in this sense, the approach provides a means of systematically improving upon the use of approximate KE functionals in DFT embedding.
Many-Body Basis Set Superposition Effect.
Ouyang, John F; Bettens, Ryan P A
2015-11-10
The basis set superposition effect (BSSE) arises in electronic structure calculations of molecular clusters when questions relating to interactions between monomers within the larger cluster are asked. The binding energy, or total energy, of the cluster may be broken down into many smaller subcluster calculations and the energies of these subsystems linearly combined to, hopefully, produce the desired quantity of interest. Unfortunately, BSSE can plague these smaller fragment calculations. In this work, we carefully examine the major sources of error associated with reproducing the binding energy and total energy of a molecular cluster. In order to do so, we decompose these energies in terms of a many-body expansion (MBE), where a "body" here refers to the monomers that make up the cluster. In our analysis, we found it necessary to introduce something we designate here as a many-ghost many-body expansion (MGMBE). The work presented here produces some surprising results, but perhaps the most significant of all is that BSSE effects up to the order of truncation in a MBE of the total energy cancel exactly. In the case of the binding energy, the only BSSE correction terms remaining arise from the removal of the one-body monomer total energies. Nevertheless, our earlier work indicated that BSSE effects continued to remain in the total energy of the cluster up to very high truncation order in the MBE. We show in this work that the vast majority of these high-order many-body effects arise from BSSE associated with the one-body monomer total energies. Also, we found that, remarkably, the complete basis set limit values for the three-body and four-body interactions differed very little from that at the MP2/aug-cc-pVDZ level for the respective subclusters embedded within a larger cluster. PMID:26574311
Gravitational Lens Modeling with Basis Sets
NASA Astrophysics Data System (ADS)
Birrer, Simon; Amara, Adam; Refregier, Alexandre
2015-11-01
We present a strong lensing modeling technique based on versatile basis sets for the lens and source planes. Our method uses high performance Monte Carlo algorithms, allows for an adaptive build up of complexity, and bridges the gap between parametric and pixel based reconstruction methods. We apply our method to a Hubble Space Telescope image of the strong lens system RX J1131-1231 and show that our method finds a reliable solution and is able to detect substructure in the lens and source planes simultaneously. Using mock data, we show that our method is sensitive to sub-clumps with masses four orders of magnitude smaller than the main lens, which corresponds to about {10}8{M}⊙ , without prior knowledge of the position and mass of the sub-clump. The modeling approach is flexible and maximizes automation to facilitate the analysis of the large number of strong lensing systems expected in upcoming wide field surveys. The resulting search for dark sub-clumps in these systems, without mass-to-light priors, offers promise for probing physics beyond the standard model in the dark matter sector.
Correlation consistent basis sets for the atoms In–Xe
Mahler, Andrew; Wilson, Angela K.
2015-02-28
In this work, the correlation consistent family of Gaussian basis sets has been expanded to include all-electron basis sets for In–Xe. The methodology for developing these basis sets is described, and several examples of the performance and utility of the new sets have been provided. Dissociation energies and bond lengths for both homonuclear and heteronuclear diatomics demonstrate the systematic convergence behavior with respect to increasing basis set quality expected by the family of correlation consistent basis sets in describing molecular properties. Comparison with recently developed correlation consistent sets designed for use with the Douglas-Kroll Hamiltonian is provided.
QUALITY: A program to assess basis set quality
NASA Astrophysics Data System (ADS)
Sordo, J. A.
1998-09-01
A program to analyze in detail the quality of basis sets is presented. The information provided by the application of a wide variety of (atomic and/or molecular) quality criteria is processed by using a methodology that allows one to determine the most appropriate quality test to select a basis set to compute a given (atomic or molecular) property. Fuzzy set theory is used to choose the most adequate basis set to compute simultaneously a set of properties.
Property-optimized Gaussian basis sets for molecular response calculations
NASA Astrophysics Data System (ADS)
Rappoport, Dmitrij; Furche, Filipp
2010-10-01
With recent advances in electronic structure methods, first-principles calculations of electronic response properties, such as linear and nonlinear polarizabilities, have become possible for molecules with more than 100 atoms. Basis set incompleteness is typically the main source of error in such calculations since traditional diffuse augmented basis sets are too costly to use or suffer from near linear dependence. To address this problem, we construct the first comprehensive set of property-optimized augmented basis sets for elements H-Rn except lanthanides. The new basis sets build on the Karlsruhe segmented contracted basis sets of split-valence to quadruple-zeta valence quality and add a small number of moderately diffuse basis functions. The exponents are determined variationally by maximization of atomic Hartree-Fock polarizabilities using analytical derivative methods. The performance of the resulting basis sets is assessed using a set of 313 molecular static Hartree-Fock polarizabilities. The mean absolute basis set errors are 3.6%, 1.1%, and 0.3% for property-optimized basis sets of split-valence, triple-zeta, and quadruple-zeta valence quality, respectively. Density functional and second-order Møller-Plesset polarizabilities show similar basis set convergence. We demonstrate the efficiency of our basis sets by computing static polarizabilities of icosahedral fullerenes up to C720 using hybrid density functional theory.
Tests for Wavelets as a Basis Set
NASA Astrophysics Data System (ADS)
Baker, Thomas; Evenbly, Glen; White, Steven
A wavelet transformation is a special type of filter usually reserved for image processing and other applications. We develop metrics to evaluate wavelets for general problems on test one-dimensional systems. The goal is to eventually use a wavelet basis in electronic structure calculations. We compare a variety of orthogonal wavelets such as coiflets, symlets, and daubechies wavelets. We also evaluate a new type of orthogonal wavelet with dilation factor three which is both symmetric and compact in real space. This work was supported by the U.S. Department of Energy, Office of Science, Basic Energy Sciences under Award #DE-SC008696.
Basis Set Exchange: A Community Database for Computational Sciences
Schuchardt, Karen L.; Didier, Brett T.; Elsethagen, Todd O.; Sun, Lisong; Gurumoorthi, Vidhya; Chase, Jared M.; Li, Jun; Windus, Theresa L.
2007-05-01
Basis sets are one of the most important input data for computational models in the chemistry, materials, biology and other science domains that utilize computational quantum mechanics methods. Providing a shared, web accessible environment where researchers can not only download basis sets in their required format, but browse the data, contribute new basis sets, and ultimately curate and manage the data as a community will facilitate growth of this resource and encourage sharing both data and knowledge. We describe the Basis Set Exchange (BSE), a web portal that provides advanced browsing and download capabilities, facilities for contributing basis set data, and an environment that incorporates tools to foster development and interaction of communities. The BSE leverages and enables continued development of the basis set library originally assembled at the Environmental Molecular Sciences Laboratory.
High quality Gaussian basis sets for fourth-row atoms
NASA Technical Reports Server (NTRS)
Partridge, Harry; Faegri, Knut, Jr.
1992-01-01
Energy optimized Gaussian basis sets of triple-zeta quality for the atoms Rb-Xe have been derived. Two series of basis sets are developed: (24s 16p 10d) and (26s 16p 10d) sets which were expanded to 13d and 19p functions as the 4d and 5p shells become occupied. For the atoms lighter than Cd, the (24s 16p 10d) sets with triple-zeta valence distributions are higher in energy than the corresponding double-zeta distribution. To ensure a triple-zeta distribution and a global energy minimum, the (26s 16p 10d) sets were derived. Total atomic energies from the largest basis sets are between 198 and 284 (mu)E(sub H) above the numerical Hartree-Fock energies.
The ORP basis set designed for optical rotation calculations.
Baranowska-Łączkowska, Angelika; Łączkowski, Krzysztof Z
2013-09-01
Details of generation of the optical rotation prediction (ORP) basis set developed for accurate optical rotation (OR) calculations are presented. Specific rotation calculations carried out at the density functional theory (DFT) level for model chiral methane molecule, fluorooxirane, methyloxirane, and dimethylmethylenecyclopropane reveal that the ORP set outperforms larger basis sets, among them the aug-cc-pVTZ basis set of Dunning (J. Chem. Phys. 1989, 90, 1007) and the aug-pc-2 basis set of Jensen (J. Chem. Phys. 2002, 117, 9234; J. Chem. Theory Comput. 2008, 4, 719). It is shown to be an attractive choice also in the case of larger systems, namely norbornanone, β-pinene, trans-pinane, and nopinone. The ORP basis set is further used in OR calculations for 24 other systems, and the results are compared to the aug-cc-pVDZ values. Whenever large discrepancies of results are observed, the ORP values are in an excellent agreement with the aug-cc-pVTZ results. The ORP basis set enables accurate specific rotation calculations at a reduced cost and thus can be recommended for routine DFT OR calculations, also for large and conformationally flexible molecules.
Periodic local MP2 method employing orbital specific virtuals
Usvyat, Denis Schütz, Martin; Maschio, Lorenzo
2015-09-14
We introduce orbital specific virtuals (OSVs) to represent the truncated pair-specific virtual space in periodic local Møller-Plesset perturbation theory of second order (LMP2). The OSVs are constructed by diagonalization of the LMP2 amplitude matrices which correspond to diagonal Wannier-function (WF) pairs. Only a subset of these OSVs is adopted for the subsequent OSV-LMP2 calculation, namely, those with largest contribution to the diagonal pair correlation energy and with the accumulated value of these contributions reaching a certain accuracy. The virtual space for a general (non diagonal) pair is spanned by the union of the two OSV sets related to the individual WFs of the pair. In the periodic LMP2 method, the diagonal LMP2 amplitude matrices needed for the construction of the OSVs are calculated in the basis of projected atomic orbitals (PAOs), employing very large PAO domains. It turns out that the OSVs are excellent to describe short range correlation, yet less appropriate for long range van der Waals correlation. In order to compensate for this bias towards short range correlation, we augment the virtual space spanned by the OSVs by the most diffuse PAOs of the corresponding minimal PAO domain. The Fock and overlap matrices in OSV basis are constructed in the reciprocal space. The 4-index electron repulsion integrals are calculated by local density fitting and, for distant pairs, via multipole approximation. New procedures for determining the fit-domains and the distant-pair lists, leading to higher efficiency in the 4-index integral evaluation, have been implemented. Generally, and in contrast to our previous PAO based periodic LMP2 method, the OSV-LMP2 method does not require anymore great care in the specification of the individual domains (to get a balanced description when calculating energy differences) and is in that sense a black box procedure. Discontinuities in potential energy surfaces, which may occur for PAO-based calculations if one is not
Periodic local MP2 method employing orbital specific virtuals.
Usvyat, Denis; Maschio, Lorenzo; Schütz, Martin
2015-09-14
We introduce orbital specific virtuals (OSVs) to represent the truncated pair-specific virtual space in periodic local Møller-Plesset perturbation theory of second order (LMP2). The OSVs are constructed by diagonalization of the LMP2 amplitude matrices which correspond to diagonal Wannier-function (WF) pairs. Only a subset of these OSVs is adopted for the subsequent OSV-LMP2 calculation, namely, those with largest contribution to the diagonal pair correlation energy and with the accumulated value of these contributions reaching a certain accuracy. The virtual space for a general (non diagonal) pair is spanned by the union of the two OSV sets related to the individual WFs of the pair. In the periodic LMP2 method, the diagonal LMP2 amplitude matrices needed for the construction of the OSVs are calculated in the basis of projected atomic orbitals (PAOs), employing very large PAO domains. It turns out that the OSVs are excellent to describe short range correlation, yet less appropriate for long range van der Waals correlation. In order to compensate for this bias towards short range correlation, we augment the virtual space spanned by the OSVs by the most diffuse PAOs of the corresponding minimal PAO domain. The Fock and overlap matrices in OSV basis are constructed in the reciprocal space. The 4-index electron repulsion integrals are calculated by local density fitting and, for distant pairs, via multipole approximation. New procedures for determining the fit-domains and the distant-pair lists, leading to higher efficiency in the 4-index integral evaluation, have been implemented. Generally, and in contrast to our previous PAO based periodic LMP2 method, the OSV-LMP2 method does not require anymore great care in the specification of the individual domains (to get a balanced description when calculating energy differences) and is in that sense a black box procedure. Discontinuities in potential energy surfaces, which may occur for PAO-based calculations if one is not
Periodic local MP2 method employing orbital specific virtuals.
Usvyat, Denis; Maschio, Lorenzo; Schütz, Martin
2015-09-14
We introduce orbital specific virtuals (OSVs) to represent the truncated pair-specific virtual space in periodic local Møller-Plesset perturbation theory of second order (LMP2). The OSVs are constructed by diagonalization of the LMP2 amplitude matrices which correspond to diagonal Wannier-function (WF) pairs. Only a subset of these OSVs is adopted for the subsequent OSV-LMP2 calculation, namely, those with largest contribution to the diagonal pair correlation energy and with the accumulated value of these contributions reaching a certain accuracy. The virtual space for a general (non diagonal) pair is spanned by the union of the two OSV sets related to the individual WFs of the pair. In the periodic LMP2 method, the diagonal LMP2 amplitude matrices needed for the construction of the OSVs are calculated in the basis of projected atomic orbitals (PAOs), employing very large PAO domains. It turns out that the OSVs are excellent to describe short range correlation, yet less appropriate for long range van der Waals correlation. In order to compensate for this bias towards short range correlation, we augment the virtual space spanned by the OSVs by the most diffuse PAOs of the corresponding minimal PAO domain. The Fock and overlap matrices in OSV basis are constructed in the reciprocal space. The 4-index electron repulsion integrals are calculated by local density fitting and, for distant pairs, via multipole approximation. New procedures for determining the fit-domains and the distant-pair lists, leading to higher efficiency in the 4-index integral evaluation, have been implemented. Generally, and in contrast to our previous PAO based periodic LMP2 method, the OSV-LMP2 method does not require anymore great care in the specification of the individual domains (to get a balanced description when calculating energy differences) and is in that sense a black box procedure. Discontinuities in potential energy surfaces, which may occur for PAO-based calculations if one is not
Point Set Denoising Using Bootstrap-Based Radial Basis Function.
Liew, Khang Jie; Ramli, Ahmad; Abd Majid, Ahmad
2016-01-01
This paper examines the application of a bootstrap test error estimation of radial basis functions, specifically thin-plate spline fitting, in surface smoothing. The presence of noisy data is a common issue of the point set model that is generated from 3D scanning devices, and hence, point set denoising is one of the main concerns in point set modelling. Bootstrap test error estimation, which is applied when searching for the smoothing parameters of radial basis functions, is revisited. The main contribution of this paper is a smoothing algorithm that relies on a bootstrap-based radial basis function. The proposed method incorporates a k-nearest neighbour search and then projects the point set to the approximated thin-plate spline surface. Therefore, the denoising process is achieved, and the features are well preserved. A comparison of the proposed method with other smoothing methods is also carried out in this study.
Point Set Denoising Using Bootstrap-Based Radial Basis Function
Ramli, Ahmad; Abd. Majid, Ahmad
2016-01-01
This paper examines the application of a bootstrap test error estimation of radial basis functions, specifically thin-plate spline fitting, in surface smoothing. The presence of noisy data is a common issue of the point set model that is generated from 3D scanning devices, and hence, point set denoising is one of the main concerns in point set modelling. Bootstrap test error estimation, which is applied when searching for the smoothing parameters of radial basis functions, is revisited. The main contribution of this paper is a smoothing algorithm that relies on a bootstrap-based radial basis function. The proposed method incorporates a k-nearest neighbour search and then projects the point set to the approximated thin-plate spline surface. Therefore, the denoising process is achieved, and the features are well preserved. A comparison of the proposed method with other smoothing methods is also carried out in this study. PMID:27315105
Unambiguous optimization of effective potentials in finite basis sets.
Jacob, Christoph R
2011-12-28
The optimization of effective potentials is of interest in density-functional theory (DFT) in two closely related contexts. First, the evaluation of the functional derivative of orbital-dependent exchange-correlation functionals requires the application of optimized effective potential methods. Second, the optimization of the effective local potential that yields a given electron density is important both for the development of improved approximate functionals and for the practical application of embedding schemes based on DFT. However, in all cases this optimization turns into an ill-posed problem if a finite basis set is introduced for the Kohn-Sham orbitals. So far, this problem has not been solved satisfactorily. Here, a new approach to overcome the ill-posed nature of such finite-basis set methods is presented for the optimization of the effective local potential that yields a given electron density. This new scheme can be applied with orbital basis sets of reasonable size and makes it possible to vary the basis sets for the orbitals and for the potential independently, while providing an unambiguous potential that systematically approaches the numerical reference.
Scar Functions, Barriers for Chemical Reactivity, and Vibrational Basis Sets.
Revuelta, F; Vergini, E; Benito, R M; Borondo, F
2016-07-14
The performance of a recently proposed method to efficiently calculate scar functions is analyzed in problems of chemical interest. An application to the computation of wave functions associated with barriers relevant for the LiNC ⇄ LiCN isomerization reaction is presented as an illustration. These scar functions also constitute excellent elements for basis sets suitable for quantum calculation of vibrational energy levels. To illustrate their efficiency, a calculation of the LiNC/LiCN eigenfunctions is also presented.
Spin-Polarized Nonadiabatic Dynamics with Local Basis Sets
NASA Astrophysics Data System (ADS)
Hoyt, Robert; Kolesov, Grigory; Tritsaris, Georgios; Granas, Oscar; Efthimios, Efthimios
Accurate simulations of electron transfer at the solid-electrolyte interphase (SEI) are critical for understanding and predicting electrochemical reactions. Density-Functional Theory (DFT) has been widely applied to study the ground-state structure of novel materials for electrochemical energy storage and for adiabatic molecular dynamics. Unfortunately, many chemical reactions take place on femtosecond time scales where assuming adiabatic electron density propagation is invalid. To resolve this, we have developed the ability to perform time-dependent DFT calculations using nonadiabatic propagation of the electron density along with Ehrenfest dynamics for the ions to better capture the complex interactions that occur during surface-electrolyte electron transfer and chemical reactions. Spin polarization is also implemented to improve the accuracy of the simulations and their suitability for studying a wider range of chemical reactions. Local basis sets are implemented via linear combinations of atomic orbitals to reduce the size of the DFT basis for computational efficiency.
Coupled-cluster based basis sets for valence correlation calculations
NASA Astrophysics Data System (ADS)
Claudino, Daniel; Gargano, Ricardo; Bartlett, Rodney J.
2016-03-01
Novel basis sets are generated that target the description of valence correlation in atoms H through Ar. The new contraction coefficients are obtained according to the Atomic Natural Orbital (ANO) procedure from CCSD(T) (coupled-cluster singles and doubles with perturbative triples correction) density matrices starting from the primitive functions of Dunning et al. [J. Chem. Phys. 90, 1007 (1989); ibid. 98, 1358 (1993); ibid. 100, 2975 (1993)] (correlation consistent polarized valence X-tuple zeta, cc-pVXZ). The exponents of the primitive Gaussian functions are subject to uniform scaling in order to ensure satisfaction of the virial theorem for the corresponding atoms. These new sets, named ANO-VT-XZ (Atomic Natural Orbital Virial Theorem X-tuple Zeta), have the same number of contracted functions as their cc-pVXZ counterparts in each subshell. The performance of these basis sets is assessed by the evaluation of the contraction errors in four distinct computations: correlation energies in atoms, probing the density in different regions of space via
Coupled-cluster based basis sets for valence correlation calculations.
Claudino, Daniel; Gargano, Ricardo; Bartlett, Rodney J
2016-03-14
Novel basis sets are generated that target the description of valence correlation in atoms H through Ar. The new contraction coefficients are obtained according to the Atomic Natural Orbital (ANO) procedure from CCSD(T) (coupled-cluster singles and doubles with perturbative triples correction) density matrices starting from the primitive functions of Dunning et al. [J. Chem. Phys. 90, 1007 (1989); ibid. 98, 1358 (1993); ibid. 100, 2975 (1993)] (correlation consistent polarized valence X-tuple zeta, cc-pVXZ). The exponents of the primitive Gaussian functions are subject to uniform scaling in order to ensure satisfaction of the virial theorem for the corresponding atoms. These new sets, named ANO-VT-XZ (Atomic Natural Orbital Virial Theorem X-tuple Zeta), have the same number of contracted functions as their cc-pVXZ counterparts in each subshell. The performance of these basis sets is assessed by the evaluation of the contraction errors in four distinct computations: correlation energies in atoms, probing the density in different regions of space via ⟨r(n)⟩ (-3 ≤ n ≤ 3) in atoms, correlation energies in diatomic molecules, and the quality of fitting potential energy curves as measured by spectroscopic constants. All energy calculations with ANO-VT-QZ have contraction errors within "chemical accuracy" of 1 kcal/mol, which is not true for cc-pVQZ, suggesting some improvement compared to the correlation consistent series of Dunning and co-workers.
Coupled-cluster based basis sets for valence correlation calculations.
Claudino, Daniel; Gargano, Ricardo; Bartlett, Rodney J
2016-03-14
Novel basis sets are generated that target the description of valence correlation in atoms H through Ar. The new contraction coefficients are obtained according to the Atomic Natural Orbital (ANO) procedure from CCSD(T) (coupled-cluster singles and doubles with perturbative triples correction) density matrices starting from the primitive functions of Dunning et al. [J. Chem. Phys. 90, 1007 (1989); ibid. 98, 1358 (1993); ibid. 100, 2975 (1993)] (correlation consistent polarized valence X-tuple zeta, cc-pVXZ). The exponents of the primitive Gaussian functions are subject to uniform scaling in order to ensure satisfaction of the virial theorem for the corresponding atoms. These new sets, named ANO-VT-XZ (Atomic Natural Orbital Virial Theorem X-tuple Zeta), have the same number of contracted functions as their cc-pVXZ counterparts in each subshell. The performance of these basis sets is assessed by the evaluation of the contraction errors in four distinct computations: correlation energies in atoms, probing the density in different regions of space via ⟨r(n)⟩ (-3 ≤ n ≤ 3) in atoms, correlation energies in diatomic molecules, and the quality of fitting potential energy curves as measured by spectroscopic constants. All energy calculations with ANO-VT-QZ have contraction errors within "chemical accuracy" of 1 kcal/mol, which is not true for cc-pVQZ, suggesting some improvement compared to the correlation consistent series of Dunning and co-workers. PMID:26979680
Scar Functions, Barriers for Chemical Reactivity, and Vibrational Basis Sets.
Revuelta, F; Vergini, E; Benito, R M; Borondo, F
2016-07-14
The performance of a recently proposed method to efficiently calculate scar functions is analyzed in problems of chemical interest. An application to the computation of wave functions associated with barriers relevant for the LiNC ⇄ LiCN isomerization reaction is presented as an illustration. These scar functions also constitute excellent elements for basis sets suitable for quantum calculation of vibrational energy levels. To illustrate their efficiency, a calculation of the LiNC/LiCN eigenfunctions is also presented. PMID:26905100
The orbital-specific virtual local triples correction: OSV-L(T).
Schütz, Martin; Yang, Jun; Chan, Garnet Kin-Lic; Manby, Frederick R; Werner, Hans-Joachim
2013-02-01
A local method based on orbital specific virtuals (OSVs) for calculating the perturbative triples correction in local coupled cluster calculations is presented. In contrast to the previous approach based on projected atomic orbitals (PAOs), described by Schütz [J. Chem. Phys. 113, 9986 (2000)], the new scheme works without any ad hoc truncations of the virtual space to domains. A single threshold defines the pair and triple specific virtual spaces completely and automatically. It is demonstrated that the computational cost of the method scales linearly with molecular size. Employing the recommended threshold a similar fraction of the correlation energy is recovered as with the original PAO method at a somewhat lower cost. A benchmark for 52 reactions demonstrates that for reaction energies the intrinsic accuracy of the coupled cluster with singles and doubles excitations and a perturbative treatment of triples excitations method can be reached by OSV-local coupled cluster theory with singles and doubles and perturbative triples, provided a MP2 correction is applied that accounts for basis set incompleteness errors as well as for remaining domain errors. As an application example the interaction energies of the guanine-cytosine dimers in the Watson-Crick and stacked arrangements are investigated at the level of local coupled cluster theory with singles and doubles and perturbative triples. Based on these calculations we propose new complete-basis-set-limit estimates for these interaction energies at this level of theory.
Basis set expansion for inverse problems in plasma diagnostic analysis.
Jones, B; Ruiz, C L
2013-07-01
A basis set expansion method [V. Dribinski, A. Ossadtchi, V. A. Mandelshtam, and H. Reisler, Rev. Sci. Instrum. 73, 2634 (2002)] is applied to recover physical information about plasma radiation sources from instrument data, which has been forward transformed due to the nature of the measurement technique. This method provides a general approach for inverse problems, and we discuss two specific examples relevant to diagnosing fast z pinches on the 20-25 MA Z machine [M. E. Savage, L. F. Bennett, D. E. Bliss, W. T. Clark, R. S. Coats, J. M. Elizondo, K. R. LeChien, H. C. Harjes, J. M. Lehr, J. E. Maenchen, D. H. McDaniel, M. F. Pasik, T. D. Pointon, A. C. Owen, D. B. Seidel, D. L. Smith, B. S. Stoltzfus, K. W. Struve, W. A. Stygar, L. K. Warne, J. R. Woodworth, C. W. Mendel, K. R. Prestwich, R. W. Shoup, D. L. Johnson, J. P. Corley, K. C. Hodge, T. C. Wagoner, and P. E. Wakeland, in Proceedings of the Pulsed Power Plasma Sciences Conference (IEEE, 2007), p. 979]. First, Abel inversion of time-gated, self-emission x-ray images from a wire array implosion is studied. Second, we present an approach for unfolding neutron time-of-flight measurements from a deuterium gas puff z pinch to recover information about emission time history and energy distribution. Through these examples, we discuss how noise in the measured data limits the practical resolution of the inversion, and how the method handles discontinuities in the source function and artifacts in the projected image. We add to the method a propagation of errors calculation for estimating uncertainties in the inverted solution.
Basis set expansion for inverse problems in plasma diagnostic analysis
Jones, B.; Ruiz, C. L.
2013-07-15
A basis set expansion method [V. Dribinski, A. Ossadtchi, V. A. Mandelshtam, and H. Reisler, Rev. Sci. Instrum. 73, 2634 (2002)] is applied to recover physical information about plasma radiation sources from instrument data, which has been forward transformed due to the nature of the measurement technique. This method provides a general approach for inverse problems, and we discuss two specific examples relevant to diagnosing fast z pinches on the 20–25 MA Z machine [M. E. Savage, L. F. Bennett, D. E. Bliss, W. T. Clark, R. S. Coats, J. M. Elizondo, K. R. LeChien, H. C. Harjes, J. M. Lehr, J. E. Maenchen, D. H. McDaniel, M. F. Pasik, T. D. Pointon, A. C. Owen, D. B. Seidel, D. L. Smith, B. S. Stoltzfus, K. W. Struve, W. A. Stygar, L. K. Warne, J. R. Woodworth, C. W. Mendel, K. R. Prestwich, R. W. Shoup, D. L. Johnson, J. P. Corley, K. C. Hodge, T. C. Wagoner, and P. E. Wakeland, in Proceedings of the Pulsed Power Plasma Sciences Conference (IEEE, 2007), p. 979]. First, Abel inversion of time-gated, self-emission x-ray images from a wire array implosion is studied. Second, we present an approach for unfolding neutron time-of-flight measurements from a deuterium gas puff z pinch to recover information about emission time history and energy distribution. Through these examples, we discuss how noise in the measured data limits the practical resolution of the inversion, and how the method handles discontinuities in the source function and artifacts in the projected image. We add to the method a propagation of errors calculation for estimating uncertainties in the inverted solution.
Basis set expansion for inverse problems in plasma diagnostic analysis
NASA Astrophysics Data System (ADS)
Jones, B.; Ruiz, C. L.
2013-07-01
A basis set expansion method [V. Dribinski, A. Ossadtchi, V. A. Mandelshtam, and H. Reisler, Rev. Sci. Instrum. 73, 2634 (2002)], 10.1063/1.1482156 is applied to recover physical information about plasma radiation sources from instrument data, which has been forward transformed due to the nature of the measurement technique. This method provides a general approach for inverse problems, and we discuss two specific examples relevant to diagnosing fast z pinches on the 20-25 MA Z machine [M. E. Savage, L. F. Bennett, D. E. Bliss, W. T. Clark, R. S. Coats, J. M. Elizondo, K. R. LeChien, H. C. Harjes, J. M. Lehr, J. E. Maenchen, D. H. McDaniel, M. F. Pasik, T. D. Pointon, A. C. Owen, D. B. Seidel, D. L. Smith, B. S. Stoltzfus, K. W. Struve, W. A. Stygar, L. K. Warne, J. R. Woodworth, C. W. Mendel, K. R. Prestwich, R. W. Shoup, D. L. Johnson, J. P. Corley, K. C. Hodge, T. C. Wagoner, and P. E. Wakeland, in Proceedings of the Pulsed Power Plasma Sciences Conference (IEEE, 2007), p. 979]. First, Abel inversion of time-gated, self-emission x-ray images from a wire array implosion is studied. Second, we present an approach for unfolding neutron time-of-flight measurements from a deuterium gas puff z pinch to recover information about emission time history and energy distribution. Through these examples, we discuss how noise in the measured data limits the practical resolution of the inversion, and how the method handles discontinuities in the source function and artifacts in the projected image. We add to the method a propagation of errors calculation for estimating uncertainties in the inverted solution.
NASA Astrophysics Data System (ADS)
Nikolaev, A. V.; Lamoen, D.; Partoens, B.
2016-07-01
In order to increase the accuracy of the linearized augmented plane wave (LAPW) method, we present a new approach where the plane wave basis function is augmented by two different atomic radial components constructed at two different linearization energies corresponding to two different electron bands (or energy windows). We demonstrate that this case can be reduced to the standard treatment within the LAPW paradigm where the usual basis set is enriched by the basis functions of the tight binding type, which go to zero with zero derivative at the sphere boundary. We show that the task is closely related with the problem of extended core states which is currently solved by applying the LAPW method with local orbitals (LAPW+LO). In comparison with LAPW+LO, the number of supplemented basis functions in our approach is doubled, which opens up a new channel for the extension of the LAPW and LAPW+LO basis sets. The appearance of new supplemented basis functions absent in the LAPW+LO treatment is closely related with the existence of the u ˙ l -component in the canonical LAPW method. We discuss properties of additional tight binding basis functions and apply the extended basis set for computation of electron energy bands of lanthanum (face and body centered structures) and hexagonal close packed lattice of cadmium. We demonstrate that the new treatment gives lower total energies in comparison with both canonical LAPW and LAPW+LO, with the energy difference more pronounced for intermediate and poor LAPW basis sets.
Hill, J. Grant E-mail: kipeters@wsu.edu; Peterson, Kirk A. E-mail: kipeters@wsu.edu
2014-09-07
New correlation consistent basis sets, cc-pVnZ-PP-F12 (n = D, T, Q), for all the post-d main group elements Ga–Rn have been optimized for use in explicitly correlated F12 calculations. The new sets, which include not only orbital basis sets but also the matching auxiliary sets required for density fitting both conventional and F12 integrals, are designed for correlation of valence sp, as well as the outer-core d electrons. The basis sets are constructed for use with the previously published small-core relativistic pseudopotentials of the Stuttgart-Cologne variety. Benchmark explicitly correlated coupled-cluster singles and doubles with perturbative triples [CCSD(T)-F12b] calculations of the spectroscopic properties of numerous diatomic molecules involving 4p, 5p, and 6p elements have been carried out and compared to the analogous conventional CCSD(T) results. In general the F12 results obtained with a n-zeta F12 basis set were comparable to conventional aug-cc-pVxZ-PP or aug-cc-pwCVxZ-PP basis set calculations obtained with x = n + 1 or even x = n + 2. The new sets used in CCSD(T)-F12b calculations are particularly efficient at accurately recovering the large correlation effects of the outer-core d electrons.
Hill, J Grant
2011-07-28
Auxiliary basis sets specifically matched to the correlation consistent cc-pVnZ-PP, cc-pwCVnZ-PP, aug-cc-pVnZ-PP, and aug-cc-pwCVnZ-PP orbital basis sets (used in conjunction with pseudopotentials) for the 5d transition metal elements Hf-Pt have been optimized for use in density fitting second-order Møller-Plesset perturbation theory and other correlated ab initio methods. Calculations of the second-order Møller-Plesset perturbation theory correlation energy, for a test set of small to medium sized molecules, indicate that the density fitting error when utilizing these sets is negligible at three to four orders of magnitude smaller than the orbital basis set incompleteness error.
Miliordos, Evangelos; Xantheas, Sotiris S.
2015-03-07
We report the variation of the binding energy of the Formic Acid Dimer with the size of the basis set at the Coupled Cluster with iterative Singles, Doubles and perturbatively connected Triple replacements [CCSD(T)] level of theory, estimate the Complete Basis Set (CBS) limit, and examine the validity of the Basis Set Superposition Error (BSSE)-correction for this quantity that was previously challenged by Kalescky, Kraka, and Cremer (KKC) [J. Chem. Phys. 140, 084315 (2014)]. Our results indicate that the BSSE correction, including terms that account for the substantial geometry change of the monomers due to the formation of two strong hydrogen bonds in the dimer, is indeed valid for obtaining accurate estimates for the binding energy of this system as it exhibits the expected decrease with increasing basis set size. We attribute the discrepancy between our current results and those of KKC to their use of a valence basis set in conjunction with the correlation of all electrons (i.e., including the 1s of C and O). We further show that the use of a core-valence set in conjunction with all electron correlation converges faster to the CBS limit as the BSSE correction is less than half than the valence electron/valence basis set case. The uncorrected and BSSE-corrected binding energies were found to produce the same (within 0.1 kcal/mol) CBS limits. We obtain CCSD(T)/CBS best estimates for D{sub e} = − 16.1 ± 0.1 kcal/mol and for D{sub 0} = − 14.3 ± 0.1 kcal/mol, the later in excellent agreement with the experimental value of −14.22 ± 0.12 kcal/mol.
Miliordos, Evangelos; Xantheas, Sotiris S
2015-03-01
We report the variation of the binding energy of the Formic Acid Dimer with the size of the basis set at the Coupled Cluster with iterative Singles, Doubles and perturbatively connected Triple replacements [CCSD(T)] level of theory, estimate the Complete Basis Set (CBS) limit, and examine the validity of the Basis Set Superposition Error (BSSE)-correction for this quantity that was previously challenged by Kalescky, Kraka, and Cremer (KKC) [J. Chem. Phys. 140, 084315 (2014)]. Our results indicate that the BSSE correction, including terms that account for the substantial geometry change of the monomers due to the formation of two strong hydrogen bonds in the dimer, is indeed valid for obtaining accurate estimates for the binding energy of this system as it exhibits the expected decrease with increasing basis set size. We attribute the discrepancy between our current results and those of KKC to their use of a valence basis set in conjunction with the correlation of all electrons (i.e., including the 1s of C and O). We further show that the use of a core-valence set in conjunction with all electron correlation converges faster to the CBS limit as the BSSE correction is less than half than the valence electron/valence basis set case. The uncorrected and BSSE-corrected binding energies were found to produce the same (within 0.1 kcal/mol) CBS limits. We obtain CCSD(T)/CBS best estimates for De = - 16.1 ± 0.1 kcal/mol and for D0 = - 14.3 ± 0.1 kcal/mol, the later in excellent agreement with the experimental value of -14.22 ± 0.12 kcal/mol.
Gidofalvi, Gergely; Mazziotti, David A
2014-01-16
Molecule-optimized basis sets, based on approximate natural orbitals, are developed for accelerating the convergence of quantum calculations with strongly correlated (multireferenced) electrons. We use a low-cost approximate solution of the anti-Hermitian contracted Schrödinger equation (ACSE) for the one- and two-electron reduced density matrices (RDMs) to generate an approximate set of natural orbitals for strongly correlated quantum systems. The natural-orbital basis set is truncated to generate a molecule-optimized basis set whose rank matches that of a standard correlation-consistent basis set optimized for the atoms. We show that basis-set truncation by approximate natural orbitals can be viewed as a one-electron unitary transformation of the Hamiltonian operator and suggest an extension of approximate natural-orbital truncations through two-electron unitary transformations of the Hamiltonian operator, such as those employed in the solution of the ACSE. The molecule-optimized basis set from the ACSE improves the accuracy of the equivalent standard atom-optimized basis set at little additional computational cost. We illustrate the method with the potential energy curves of hydrogen fluoride and diatomic nitrogen. Relative to the hydrogen fluoride potential energy curve from the ACSE in a polarized triple-ζ basis set, the ACSE curve in a molecule-optimized basis set, equivalent in size to a polarized double-ζ basis, has a nonparallelity error of 0.0154 au, which is significantly better than the nonparallelity error of 0.0252 au from the polarized double-ζ basis set.
Spackman, Peter R; Jayatilaka, Dylan; Karton, Amir
2016-09-14
We examine the basis set convergence of the CCSD(T) method for obtaining the structures of the 108 neutral first- and second-row species in the W4-11 database (with up to five non-hydrogen atoms). This set includes a total of 181 unique bonds: 75 H-X, 49 X-Y, 43 X=Y, and 14 X≡Y bonds (where X and Y are first- and second-row atoms). As reference values, geometries optimized at the CCSD(T)/aug'-cc-pV(6+d)Z level of theory are used. We consider the basis set convergence of the CCSD(T) method with the correlation consistent basis sets cc-pV(n+d)Z and aug'-cc-pV(n+d)Z (n = D, T, Q, 5) and the Weigend-Ahlrichs def2-n ZVPP basis sets (n = T, Q). For each increase in the highest angular momentum present in the basis set, the root-mean-square deviation (RMSD) over the bond distances is decreased by a factor of ∼4. For example, the following RMSDs are obtained for the cc-pV(n+d)Z basis sets 0.0196 (D), 0.0050 (T), 0.0015 (Q), and 0.0004 (5) Å. Similar results are obtained for the aug'-cc-pV(n+d)Z and def2-n ZVPP basis sets. The double-zeta and triple-zeta quality basis sets systematically and significantly overestimate the bond distances. A simple and cost-effective way to improve the performance of these basis sets is to scale the bond distances by an empirical scaling factor of 0.9865 (cc-pV(D+d)Z) and 0.9969 (cc-pV(T+d)Z). This results in RMSDs of 0.0080 (scaled cc-pV(D+d)Z) and 0.0029 (scaled cc-pV(T+d)Z) Å. The basis set convergence of larger basis sets can be accelerated via standard basis-set extrapolations. In addition, the basis set convergence of explicitly correlated CCSD(T)-F12 calculations is investigated in conjunction with the cc-pVnZ-F12 basis sets (n = D, T). Typically, one "gains" two angular momenta in the explicitly correlated calculations. That is, the CCSD(T)-F12/cc-pVnZ-F12 level of theory shows similar performance to the CCSD(T)/cc-pV(n+2)Z level of theory. In particular, the following RMSDs are obtained for the cc-pVnZ-F12 basis sets 0.0019 (D
Spackman, Peter R; Jayatilaka, Dylan; Karton, Amir
2016-09-14
We examine the basis set convergence of the CCSD(T) method for obtaining the structures of the 108 neutral first- and second-row species in the W4-11 database (with up to five non-hydrogen atoms). This set includes a total of 181 unique bonds: 75 H-X, 49 X-Y, 43 X=Y, and 14 X≡Y bonds (where X and Y are first- and second-row atoms). As reference values, geometries optimized at the CCSD(T)/aug'-cc-pV(6+d)Z level of theory are used. We consider the basis set convergence of the CCSD(T) method with the correlation consistent basis sets cc-pV(n+d)Z and aug'-cc-pV(n+d)Z (n = D, T, Q, 5) and the Weigend-Ahlrichs def2-n ZVPP basis sets (n = T, Q). For each increase in the highest angular momentum present in the basis set, the root-mean-square deviation (RMSD) over the bond distances is decreased by a factor of ∼4. For example, the following RMSDs are obtained for the cc-pV(n+d)Z basis sets 0.0196 (D), 0.0050 (T), 0.0015 (Q), and 0.0004 (5) Å. Similar results are obtained for the aug'-cc-pV(n+d)Z and def2-n ZVPP basis sets. The double-zeta and triple-zeta quality basis sets systematically and significantly overestimate the bond distances. A simple and cost-effective way to improve the performance of these basis sets is to scale the bond distances by an empirical scaling factor of 0.9865 (cc-pV(D+d)Z) and 0.9969 (cc-pV(T+d)Z). This results in RMSDs of 0.0080 (scaled cc-pV(D+d)Z) and 0.0029 (scaled cc-pV(T+d)Z) Å. The basis set convergence of larger basis sets can be accelerated via standard basis-set extrapolations. In addition, the basis set convergence of explicitly correlated CCSD(T)-F12 calculations is investigated in conjunction with the cc-pVnZ-F12 basis sets (n = D, T). Typically, one "gains" two angular momenta in the explicitly correlated calculations. That is, the CCSD(T)-F12/cc-pVnZ-F12 level of theory shows similar performance to the CCSD(T)/cc-pV(n+2)Z level of theory. In particular, the following RMSDs are obtained for the cc-pVnZ-F12 basis sets 0.0019 (D
NASA Astrophysics Data System (ADS)
Spackman, Peter R.; Jayatilaka, Dylan; Karton, Amir
2016-09-01
We examine the basis set convergence of the CCSD(T) method for obtaining the structures of the 108 neutral first- and second-row species in the W4-11 database (with up to five non-hydrogen atoms). This set includes a total of 181 unique bonds: 75 H—X, 49 X—Y, 43 X=Y, and 14 X≡Y bonds (where X and Y are first- and second-row atoms). As reference values, geometries optimized at the CCSD(T)/aug'-cc-pV(6+d)Z level of theory are used. We consider the basis set convergence of the CCSD(T) method with the correlation consistent basis sets cc-pV(n+d)Z and aug'-cc-pV(n+d)Z (n = D, T, Q, 5) and the Weigend-Ahlrichs def2-n ZVPP basis sets (n = T, Q). For each increase in the highest angular momentum present in the basis set, the root-mean-square deviation (RMSD) over the bond distances is decreased by a factor of ˜4. For example, the following RMSDs are obtained for the cc-pV(n+d)Z basis sets 0.0196 (D), 0.0050 (T), 0.0015 (Q), and 0.0004 (5) Å. Similar results are obtained for the aug'-cc-pV(n+d)Z and def2-n ZVPP basis sets. The double-zeta and triple-zeta quality basis sets systematically and significantly overestimate the bond distances. A simple and cost-effective way to improve the performance of these basis sets is to scale the bond distances by an empirical scaling factor of 0.9865 (cc-pV(D+d)Z) and 0.9969 (cc-pV(T+d)Z). This results in RMSDs of 0.0080 (scaled cc-pV(D+d)Z) and 0.0029 (scaled cc-pV(T+d)Z) Å. The basis set convergence of larger basis sets can be accelerated via standard basis-set extrapolations. In addition, the basis set convergence of explicitly correlated CCSD(T)-F12 calculations is investigated in conjunction with the cc-pVnZ-F12 basis sets (n = D, T). Typically, one "gains" two angular momenta in the explicitly correlated calculations. That is, the CCSD(T)-F12/cc-pVnZ-F12 level of theory shows similar performance to the CCSD(T)/cc-pV(n+2)Z level of theory. In particular, the following RMSDs are obtained for the cc-pVnZ-F12 basis sets 0
Generation of basis sets with high degree of fulfillment of the Hellmann-Feynman theorem.
Rico, J Fernández; López, R; Ema, I; Ramírez, G
2007-03-01
A direct relationship is established between the degree of fulfillment of the Hellman-Feynman (electrostatic) theorem, measured as the difference between energy derivatives and electrostatic forces, and the stability of the basis set, measured from the indices that characterize the distance of the space generated by the basis functions to the space of their derivatives with respect to the nuclear coordinates. On the basis of this relationship, a criterion for obtaining basis sets of moderate size with a high degree of fulfillment of the theorem is proposed. As an illustrative application, previously reported Slater basis sets are extended by using this criterion. The resulting augmented basis sets are tested on several molecules finding that the differences between energy gradient and electrostatic forces are reduced by at least one order of magnitude.
Plumley, Joshua A; Dannenberg, J J
2011-06-01
We evaluate the performance of ten functionals (B3LYP, M05, M05-2X, M06, M06-2X, B2PLYP, B2PLYPD, X3LYP, B97D, and MPWB1K) in combination with 16 basis sets ranging in complexity from 6-31G(d) to aug-cc-pV5Z for the calculation of the H-bonded water dimer with the goal of defining which combinations of functionals and basis sets provide a combination of economy and accuracy for H-bonded systems. We have compared the results to the best non-density functional theory (non-DFT) molecular orbital (MO) calculations and to experimental results. Several of the smaller basis sets lead to qualitatively incorrect geometries when optimized on a normal potential energy surface (PES). This problem disappears when the optimization is performed on a counterpoise (CP) corrected PES. The calculated interaction energies (ΔEs) with the largest basis sets vary from -4.42 (B97D) to -5.19 (B2PLYPD) kcal/mol for the different functionals. Small basis sets generally predict stronger interactions than the large ones. We found that, because of error compensation, the smaller basis sets gave the best results (in comparison to experimental and high-level non-DFT MO calculations) when combined with a functional that predicts a weak interaction with the largest basis set. As many applications are complex systems and require economical calculations, we suggest the following functional/basis set combinations in order of increasing complexity and cost: (1) D95(d,p) with B3LYP, B97D, M06, or MPWB1k; (2) 6-311G(d,p) with B3LYP; (3) D95++(d,p) with B3LYP, B97D, or MPWB1K; (4) 6-311++G(d,p) with B3LYP or B97D; and (5) aug-cc-pVDZ with M05-2X, M06-2X, or X3LYP.
Derivation of a formula for the resonance integral for a nonorthogonal basis set
Yim, Yung-Chang; Eyring, Henry
1981-01-01
In a self-consistent field calculation, a formula for the off-diagonal matrix elements of the core Hamiltonian is derived for a nonorthogonal basis set by a polyatomic approach. A set of parameters is then introduced for the repulsion integral formula of Mataga-Nishimoto to fit the experimental data. The matrix elements computed for the nonorthogonal basis set in the π-electron approximation are transformed to those for an orthogonal basis set by the Löwdin symmetrical orthogonalization. PMID:16593009
Dynamical basis sets for algebraic variational calculations in quantum-mechanical scattering theory
NASA Technical Reports Server (NTRS)
Sun, Yan; Kouri, Donald J.; Truhlar, Donald G.; Schwenke, David W.
1990-01-01
New basis sets are proposed for linear algebraic variational calculations of transition amplitudes in quantum-mechanical scattering problems. These basis sets are hybrids of those that yield the Kohn variational principle (KVP) and those that yield the generalized Newton variational principle (GNVP) when substituted in Schlessinger's stationary expression for the T operator. Trial calculations show that efficiencies almost as great as that of the GNVP and much greater than the KVP can be obtained, even for basis sets with the majority of the members independent of energy.
NASA Astrophysics Data System (ADS)
Richard, Ryan M.; Herbert, John M.
2013-06-01
Previous electronic structure studies that have relied on fragmentation have been primarily interested in those methods' abilities to replicate the supersystem energy (or a related energy difference) without recourse to the ability of those supersystem results to replicate experiment or high accuracy benchmarks. Here we focus on replicating accurate ab initio benchmarks, that are suitable for comparison to experimental data. In doing this it becomes imperative that we correct our methods for basis-set superposition errors (BSSE) in a computationally feasible way. This criterion leads us to develop a new method for BSSE correction, which we term the many-body counterpoise correction, or MBn for short. MBn is truncated at order n, in much the same manner as a normal many-body expansion leading to a decrease in computational time. Furthermore, its formulation in terms of fragments makes it especially suitable for use with pre-existing fragment codes. A secondary focus of this study is directed at assessing fragment methods' abilities to extrapolate to the complete basis set (CBS) limit as well as compute approximate triples corrections. Ultimately, by analysis of (H_2O)_6 and (H_2O)_{10}F^- systems, it is concluded that with large enough basis-sets (triple or quad zeta) fragment based methods can replicate high level benchmarks in a fraction of the time.
Pseudospectral sampling of Gaussian basis sets as a new avenue to high-dimensional quantum dynamics
NASA Astrophysics Data System (ADS)
Heaps, Charles
This thesis presents a novel approach to modeling quantum molecular dynamics (QMD). Theoretical approaches to QMD are essential to understanding and predicting chemical reactivity and spectroscopy. We implement a method based on a trajectory-guided basis set. In this case, the nuclei are propagated in time using classical mechanics. Each nuclear configuration corresponds to a basis function in the quantum mechanical expansion. Using the time-dependent configurations as a basis set, we are able to evolve in time using relatively little information at each time step. We use a basis set of moving frozen (time-independent width) Gaussian functions that are well-known to provide a simple and efficient basis set for nuclear dynamics. We introduce a new perspective to trajectory-guided Gaussian basis sets based on existing numerical methods. The distinction is based on the Galerkin and collocation methods. In the former, the basis set is tested using basis functions, projecting the solution onto the functional space of the problem and requiring integration over all space. In the collocation method, the Dirac delta function tests the basis set, projecting the solution onto discrete points in space. This effectively reduces the integral evaluation to function evaluation, a fundamental characteristic of pseudospectral methods. We adopt this idea for independent trajectory-guided Gaussian basis functions. We investigate a series of anharmonic vibrational models describing dynamics in up to six dimensions. The pseudospectral sampling is found to be as accurate as full integral evaluation, while the former method is fully general and integration is only possible on very particular model potential energy surfaces. Nonadiabatic dynamics are also investigated in models of photodissociation and collinear triatomic vibronic coupling. Using Ehrenfest trajectories to guide the basis set on multiple surfaces, we observe convergence to exact results using hundreds of basis functions
Haghdani, Shokouh; Åstrand, Per-Olof; Koch, Henrik
2016-02-01
We have calculated the electronic optical rotation of seven molecules using coupled cluster singles-doubles (CCSD) and the second-order approximation (CC2) employing the aug-cc-pVXZ (X = D, T, or Q) basis sets. We have also compared to time-dependent density functional theory (TDDFT) by utilizing two functionals B3LYP and CAM-B3LYP and the same basis sets. Using relative and absolute error schemes, our calculations demonstrate that the CAM-B3LYP functional predicts optical rotation with the minimum deviations compared to CCSD at λ = 355 and 589.3 nm. Furthermore, our results illustrate that the aug-cc-pVDZ basis set provides the optical rotation in good agreement with the larger basis sets for molecules not possessing small-angle optical rotation at λ = 589.3 nm. We have also performed several two-point inverse power extrapolations for the basis set convergence, i.e., OR(∞) + AX(-n), using the CC2 model at λ = 355 and 589.3 nm. Our results reveal that a two-point inverse power extrapolation with the aug-cc-pVTZ and aug-cc-pVQZ basis sets at n = 5 provides optical rotation deviations similar to those of aug-cc-pV5Z with respect to the basis limit.
Adapting DFT+U for the Chemically Motivated Correction of Minimal Basis Set Incompleteness.
Kulik, Heather J; Seelam, Natasha; Mar, Brendan D; Martínez, Todd J
2016-07-28
Recent algorithmic and hardware advances have enabled the application of electronic structure methods to the study of large-scale systems such as proteins with O(10(3)) atoms. Most such methods benefit greatly from the use of reduced basis sets to further enhance their speed, but truly minimal basis sets are well-known to suffer from incompleteness error that gives rise to incorrect descriptions of chemical bonding, preventing minimal basis set use in production calculations. We present a strategy for improving these well-known shortcomings in minimal basis sets by selectively tuning the energetics and bonding of nitrogen and oxygen atoms within proteins and small molecules to reproduce polarized double-ζ basis set geometries at minimal basis set cost. We borrow the well-known +U correction from the density functional theory community normally employed for self-interaction errors and demonstrate its power in the context of correcting basis set incompleteness within a formally self-interaction-free Hartree-Fock framework. We tune the Hubbard U parameters for nitrogen and oxygen atoms on small-molecule tautomers (e.g., cytosine), demonstrate the applicability of the approach on a number of amide-containing molecules (e.g., formamide, alanine tripeptide), and test our strategy on a 10 protein test set where anomalous proton transfer events are reduced by 90% from RHF/STO-3G to RHF/STO-3G+U, bringing the latter into quantitative agreement with RHF/6-31G* results. Although developed with the study of biological molecules in mind, this empirically tuned U approach shows promise as an alternative strategy for correction of basis set incompleteness errors.
What is the most efficient way to reach the canonical MP2 basis set limit?
NASA Astrophysics Data System (ADS)
Liakos, Dimitrios G.; Izsák, Róbert; Valeev, Edward F.; Neese, Frank
2013-09-01
Various ways of reaching the complete basis set limit at the second-order Møller-Plesset perturbation theory (MP2) level are compared with respect to their cost-to-accuracy ratio. These include: (1) traditional MP2 calculations with correlation consistent basis sets of increasing size, with and without the resolution of identity for Coulomb and exchange (RIJK) or the combined RIJ and 'chain of spheres' (RIJCOSX) approximations; (2) basis set extrapolation obtained with the same MP2 variants; and (3) explicitly correlated F12-MP2 methods. The time required to solve the Hartree-Fock equations is part of the evaluation because the overall efficiency is of central interest in this work. Results were obtained for the ISO34, DC9 and S66 test sets and were analysed in terms of efficiency and accuracy for total energies, reaction energies and their effect on the basis set superposition error. Among the methods studied, the RIJK-MP2-F12 and RIJK-MP2-EP1 (where EP1 stands for 'Extrapolation Protocol 1' as explained in the text) methods perform outstandingly well. Although extrapolation is, in general, slightly faster than explicit correlation, it is found that for reaction energies, RIJK-MP2-F12 performs systematically better. This holds especially in combination with a triple zeta basis set, in which case it even outperforms the much more costly extrapolation involving quadruple- and quintuple-zeta correlation consistent basis sets.
On basis set superposition error corrected stabilization energies for large n-body clusters.
Walczak, Katarzyna; Friedrich, Joachim; Dolg, Michael
2011-10-01
In this contribution, we propose an approximate basis set superposition error (BSSE) correction scheme for the site-site function counterpoise and for the Valiron-Mayer function counterpoise correction of second order to account for the basis set superposition error in clusters with a large number of subunits. The accuracy of the proposed scheme has been investigated for a water cluster series at the CCSD(T), CCSD, MP2, and self-consistent field levels of theory using Dunning's correlation consistent basis sets. The BSSE corrected stabilization energies for a series of water clusters are presented. A study regarding the possible savings with respect to computational resources has been carried out as well as a monitoring of the basis set dependence of the approximate BSSE corrections. PMID:21992293
Basis-set extensions for two-component spin-orbit treatments of heavy elements.
Armbruster, Markus K; Klopper, Wim; Weigend, Florian
2006-11-14
The accuracy of standard basis sets of quadruple-zeta and lower quality for the use in two-component self-consistent field procedures including spin-orbit coupling is investigated for the elements In-I and Au-At. Spin-orbit coupling leads to energetic and spatial splittings of inner shells, which are not described accurately with standard basis sets optimized for scalar relativistic calculations. This results in large errors in total atomic energies and significant errors in atomization energies of compounds containing these atoms. We show how these errors can be corrected by adding just a few steep sets of basis functions and demonstrate the quality of the resulting extended basis sets. PMID:17066175
Near Hartree-Fock quality GTO basis sets for the second-row atoms
NASA Technical Reports Server (NTRS)
Partridge, Harry
1987-01-01
Energy optimized, near Hartree-Fock quality Gaussian basis sets ranging in size from (17s12p) to (20s15p) are presented for the ground states of the second-row atoms for Na(2P), Na(+), Na(-), Mg(3P), P(-), S(-), and Cl(-). In addition, optimized supplementary functions are given for the ground state basis sets to describe the negative ions, and the excited Na(2P) and Mg(3P) atomic states. The ratios of successive orbital exponents describing the inner part of the 1s and 2p orbitals are found to be nearly independent of both nuclear charge and basis set size. This provides a method of obtaining good starting estimates for other basis set optimizations.
A Basis Set for Peptides for the Variational Approach to Conformational Kinetics.
Vitalini, F; Noé, F; Keller, B G
2015-09-01
Although Markov state models have proven to be powerful tools in resolving the complex features of biomolecular kinetics, the discretization of the conformational space has been a bottleneck since the advent of the method. A recently introduced variational approach, which uses basis functions instead of crisp conformational states, opened up a route to construct kinetic models in which the discretization error can be controlled systematically. Here, we develop and test a basis set for peptides to be used in the variational approach. The basis set is constructed by combining local residue-centered kinetic modes that are obtained from kinetic models of terminally blocked amino acids. Using this basis set, we model the conformational kinetics of two hexapeptides with sequences VGLAPG and VGVAPG. Six basis functions are sufficient to represent the slow kinetic modes of these peptides. The basis set also allows for a direct interpretation of the slow kinetic modes without an additional clustering in the space of the dominant eigenvectors. Moreover, changes in the conformational kinetics due to the exchange of leucine in VGLAPG to valine in VGVAPG can be directly quantified by comparing histograms of the basis set expansion coefficients.
NASA Astrophysics Data System (ADS)
Kupka, Teobald
2008-08-01
Based on B3LYP spin-spin coupling constants (SSCC) of several molecules calculated with cc-pV xZ, cc-pCV xZ, cc-pCV xZ-sd and cc-pCV xZ-sd+ t basis sets, a reasonably fit, using the two-parameter formula, to the Kohn-Sham complete basis set limit (CBS) is shown. Improvement in the CBS values going from cc-pV xZ to the most elaborated cc-pCV xZ-sd+ t basis set family is observed: standard deviation for all data drops from 33.7 to 23.1, and from 6.0 to 4.8 Hz after excluding problematic 1J(F,H) and 1J(F,C). Calculation of water's 1J(OH) using B3LYP/cc-pCV xZ and B3LYP/pcJ- n significantly improved the FC term convergence.
Peterson, Kirk A.; Figgen, Detlev; Goll, Erich; Stoll, Hermann; Dolg, Michael F.
2003-12-01
Series of correlation consistent basis sets have been developed for the post-d group 16-18 elements in conjunction with small-core relativistic pseudopotentials (PPs) of the energy-consistent variety. The latter were adjusted to multiconfiguration Dirac-Hartree-Fock data based on the Dirac-Coulomb-Breit Hamiltonian. The outer-core (n-1)spd shells are explicitly treated together with the nsp valence shell with these PPs. The accompanying cc-pVnZ-PP and aug-cc-pVnZ-PP basis sets range in size from DZ to 5Z quality and yield systematic convergence of both Hartree-Fock and correlated total energies. In addition to the calculation of atomic electron affinities and dipole polarizabilities of the rare gas atoms, numerous molecular benchmark calculations (HBr, HI, HAt, Br2, I2, At2, SiSe, SiTe, SiPo, KrH+, XeH+, and RnH+) are also reported at the coupled cluster level of theory. For the purposes of comparison, all-electron calculations using the Douglas-Kroll-Hess Hamiltonian have also been carried out for the halogen-containing molecules using basis sets of 5Z quality.
Informatics-Based Energy Fitting Scheme for Correlation Energy at Complete Basis Set Limit.
Seino, Junji; Nakai, Hiromi
2016-09-30
Energy fitting schemes based on informatics techniques using hierarchical basis sets with small cardinal numbers were numerically investigated to estimate correlation energies at the complete basis set limits. Numerical validations confirmed that the conventional two-point extrapolation models can be unified into a simple formula with optimal parameters obtained by the same test sets. The extrapolation model was extended to two-point fitting models by a relaxation of the relationship between the extrapolation coefficients or a change of the fitting formula. Furthermore, n-scheme fitting models were developed by the combinations of results calculated at several theory levels and basis sets to compensate for the deficiencies in the fitting model at one level of theory. Systematic assessments on the Gaussian-3X and Gaussian-2 sets revealed that the fitting models drastically reduced errors with equal or smaller computational effort. © 2016 Wiley Periodicals, Inc. PMID:27454327
A novel Gaussian-Sinc mixed basis set for electronic structure calculations
NASA Astrophysics Data System (ADS)
Jerke, Jonathan L.; Lee, Young; Tymczak, C. J.
2015-08-01
A Gaussian-Sinc basis set methodology is presented for the calculation of the electronic structure of atoms and molecules at the Hartree-Fock level of theory. This methodology has several advantages over previous methods. The all-electron electronic structure in a Gaussian-Sinc mixed basis spans both the "localized" and "delocalized" regions. A basis set for each region is combined to make a new basis methodology—a lattice of orthonormal sinc functions is used to represent the "delocalized" regions and the atom-centered Gaussian functions are used to represent the "localized" regions to any desired accuracy. For this mixed basis, all the Coulomb integrals are definable and can be computed in a dimensional separated methodology. Additionally, the Sinc basis is translationally invariant, which allows for the Coulomb singularity to be placed anywhere including on lattice sites. Finally, boundary conditions are always satisfied with this basis. To demonstrate the utility of this method, we calculated the ground state Hartree-Fock energies for atoms up to neon, the diatomic systems H2, O2, and N2, and the multi-atom system benzene. Together, it is shown that the Gaussian-Sinc mixed basis set is a flexible and accurate method for solving the electronic structure of atomic and molecular species.
A novel Gaussian-Sinc mixed basis set for electronic structure calculations
Jerke, Jonathan L.; Lee, Young; Tymczak, C. J.
2015-08-14
A Gaussian-Sinc basis set methodology is presented for the calculation of the electronic structure of atoms and molecules at the Hartree–Fock level of theory. This methodology has several advantages over previous methods. The all-electron electronic structure in a Gaussian-Sinc mixed basis spans both the “localized” and “delocalized” regions. A basis set for each region is combined to make a new basis methodology—a lattice of orthonormal sinc functions is used to represent the “delocalized” regions and the atom-centered Gaussian functions are used to represent the “localized” regions to any desired accuracy. For this mixed basis, all the Coulomb integrals are definable and can be computed in a dimensional separated methodology. Additionally, the Sinc basis is translationally invariant, which allows for the Coulomb singularity to be placed anywhere including on lattice sites. Finally, boundary conditions are always satisfied with this basis. To demonstrate the utility of this method, we calculated the ground state Hartree–Fock energies for atoms up to neon, the diatomic systems H{sub 2}, O{sub 2}, and N{sub 2}, and the multi-atom system benzene. Together, it is shown that the Gaussian-Sinc mixed basis set is a flexible and accurate method for solving the electronic structure of atomic and molecular species.
A novel Gaussian-Sinc mixed basis set for electronic structure calculations.
Jerke, Jonathan L; Lee, Young; Tymczak, C J
2015-08-14
A Gaussian-Sinc basis set methodology is presented for the calculation of the electronic structure of atoms and molecules at the Hartree-Fock level of theory. This methodology has several advantages over previous methods. The all-electron electronic structure in a Gaussian-Sinc mixed basis spans both the "localized" and "delocalized" regions. A basis set for each region is combined to make a new basis methodology-a lattice of orthonormal sinc functions is used to represent the "delocalized" regions and the atom-centered Gaussian functions are used to represent the "localized" regions to any desired accuracy. For this mixed basis, all the Coulomb integrals are definable and can be computed in a dimensional separated methodology. Additionally, the Sinc basis is translationally invariant, which allows for the Coulomb singularity to be placed anywhere including on lattice sites. Finally, boundary conditions are always satisfied with this basis. To demonstrate the utility of this method, we calculated the ground state Hartree-Fock energies for atoms up to neon, the diatomic systems H2, O2, and N2, and the multi-atom system benzene. Together, it is shown that the Gaussian-Sinc mixed basis set is a flexible and accurate method for solving the electronic structure of atomic and molecular species. PMID:26277128
Magnetic properties with multiwavelets and DFT: the complete basis set limit achieved.
Jensen, Stig Rune; Flå, Tor; Jonsson, Dan; Monstad, Rune Sørland; Ruud, Kenneth; Frediani, Luca
2016-08-01
Multiwavelets are emerging as an attractive alternative to traditional basis sets such as Gaussian-type orbitals and plane waves. One of their distinctive properties is the ability to reach the basis set limit (often a chimera for traditional approaches) reliably and consistently by fixing the desired precision ε. We present our multiwavelet implementation of the linear response formalism, applied to static magnetic properties, at the self-consistent field level of theory (both for Hartree-Fock and density functional theories). We demonstrate that the multiwavelets consistently improve the accuracy of the results when increasing the desired precision, yielding results that have four to five digits precision, thus providing a very useful benchmark which could otherwise only be estimated by extrapolation methods. Our results show that magnetizabilities obtained with the augmented quadruple-ζ basis (aug-cc-pCVQZ) are practically at the basis set limit, whereas absolute nuclear magnetic resonance shielding tensors are more challenging: even by making use of a standard extrapolation method, the accuracy is not substantially improved. In contrast, our results provide a benchmark that: (1) confirms the validity of the extrapolation ansatz; (2) can be used as a reference to achieve a property-specific extrapolation scheme, thus providing a means to obtain much better extrapolated results; (3) allows us to separate functional-specific errors from basis-set ones and thus to assess the level of cancellation between basis set and functional errors often exploited in density functional theory. PMID:27087397
Magnetic properties with multiwavelets and DFT: the complete basis set limit achieved.
Jensen, Stig Rune; Flå, Tor; Jonsson, Dan; Monstad, Rune Sørland; Ruud, Kenneth; Frediani, Luca
2016-08-01
Multiwavelets are emerging as an attractive alternative to traditional basis sets such as Gaussian-type orbitals and plane waves. One of their distinctive properties is the ability to reach the basis set limit (often a chimera for traditional approaches) reliably and consistently by fixing the desired precision ε. We present our multiwavelet implementation of the linear response formalism, applied to static magnetic properties, at the self-consistent field level of theory (both for Hartree-Fock and density functional theories). We demonstrate that the multiwavelets consistently improve the accuracy of the results when increasing the desired precision, yielding results that have four to five digits precision, thus providing a very useful benchmark which could otherwise only be estimated by extrapolation methods. Our results show that magnetizabilities obtained with the augmented quadruple-ζ basis (aug-cc-pCVQZ) are practically at the basis set limit, whereas absolute nuclear magnetic resonance shielding tensors are more challenging: even by making use of a standard extrapolation method, the accuracy is not substantially improved. In contrast, our results provide a benchmark that: (1) confirms the validity of the extrapolation ansatz; (2) can be used as a reference to achieve a property-specific extrapolation scheme, thus providing a means to obtain much better extrapolated results; (3) allows us to separate functional-specific errors from basis-set ones and thus to assess the level of cancellation between basis set and functional errors often exploited in density functional theory.
Multiple-Timestep ab Initio Molecular Dynamics Using an Atomic Basis Set Partitioning.
Steele, Ryan P
2015-12-17
This work describes an approach to accelerate ab initio Born-Oppenheimer molecular dynamics (MD) simulations by exploiting the inherent timescale separation between contributions from different atom-centered Gaussian basis sets. Several MD steps are propagated with a cost-efficient, low-level basis set, after which a dynamical correction accounts for large basis set relaxation effects in a time-reversible fashion. This multiple-timestep scheme is shown to generate valid MD trajectories, on the basis of rigorous testing for water clusters, the methanol dimer, an alanine polypeptide, protonated hydrazine, and the oxidized water dimer. This new approach generates observables that are consistent with those of target basis set trajectories, including MD-based vibrational spectra. This protocol is shown to be valid for Hartree-Fock, density functional theory, and second-order Møller-Plesset perturbation theory approaches. Recommended pairings include 6-31G as a low-level basis set for 6-31G** or 6-311G**, as well as cc-pVDZ as the subset for accurate dynamics with aug-cc-pVTZ. Demonstrated cost savings include factors of 2.6-7.3 on the systems tested and are expected to remain valid across system sizes.
Atomization Energies of SO and SO2; Basis Set Extrapolation Revisted
NASA Technical Reports Server (NTRS)
Bauschlicher, Charles W., Jr.; Ricca, Alessandra; Arnold, James (Technical Monitor)
1998-01-01
The addition of tight functions to sulphur and extrapolation to the complete basis set limit are required to obtain accurate atomization energies. Six different extrapolation procedures are tried. The best atomization energies come from the series of basis sets that yield the most consistent results for all extrapolation techniques. In the variable alpha approach, alpha values larger than 4.5 or smaller than 3, appear to suggest that the extrapolation may not be reliable. It does not appear possible to determine a reliable basis set series using only the triple and quadruple zeta based sets. The scalar relativistic effects reduce the atomization of SO and SO2 by 0.34 and 0.81 kcal/mol, respectively, and clearly must be accounted for if a highly accurate atomization energy is to be computed. The magnitude of the core-valence (CV) contribution to the atomization is affected by missing diffuse valence functions. The CV contribution is much more stable if basis set superposition errors are accounted for. A similar study of SF, SF(+), and SF6 shows that the best family of basis sets varies with the nature of the S bonding.
Balanced Basis Sets in the Calculation of Potential Energy Curves for Diatomic Molecules.
NASA Astrophysics Data System (ADS)
Barclay, V. J.
"Balanced" basis sets, which describe the internuclear region as well as the nuclear region, are examined in the context of an ab initio selection-extrapolation configuration -interaction method (MRD-CI). The sets are balanced by adding bond functions (BF's), which are s, p and d-type orbitals at the bond mid-point, to atomic-centred molecular basis sets, which have double and triple sets of valence -shell orbitals (DZ and TZ) and one or two sets of polarization functions (PF's). Potential energy curves and spectroscopic constants were calculated for the ground states of the hydrides H _2, OH, NaH, MgH, MH, SiH, PH, SH, HCl, and for the ionized species OH^+ and OH^{++}, and for the A^3Sigma_{u}, w^3Delta_{u} and B^3Pi_{g} excited states of N_2. The basis sets containing bond functions gave curves and constants superior to the DZP and (where calculated) TZPP results, and of quality similar to large basis set calculations in the literature. The single and double ionization potentials of OH, and the term energies of the N_2 excited states had error at the atomic asymptotes for all basis sets. The dissociation energies of the ground states of ten first-row diatomics (C_2, N_2, O_2, F_2, CN, CO, CF, NO, NF, and FO) were studied using balanced basis sets. A correlation was found to exist between the actual bond order of a species, and the number and kinds of orbitals which comprise the optimum BF. For MRD-CI diatomic calculations, the following BF's should be added to a DZP basis set (sp) (for a bond order of 1); 2(sp) (B. O. 1.5); (spd) (B. O. 2); 3(sp) (B. O. 2.5); 2(spd) (B. O. 3). The prescribed BF basis method was tested on the 26 second-row congeners Si _2, P_2, S _2, Cl_2, SiP, SiS, SiCl, PS, PCl, and ClS, and mixed-row congeners SiN, SiO, SiF, PO, PF, SF, SiC, PN, SO, ClF, CP, CS, CCl, NS, NCl, and ClO. An average error of 6% and a maximum error of 10% relative to known experimental D_{e }'s was found: compared to an average error of 18% for TZPP calculations
Auxiliary Basis Sets for Density Fitting in Explicitly Correlated Calculations: The Atoms H-Ar.
Kritikou, Stella; Hill, J Grant
2015-11-10
Auxiliary basis sets specifically matched to the correlation consistent cc-pVnZ-F12 and cc-pCVnZ-F12 orbital basis sets for the elements H-Ar have been optimized at the density-fitted second-order Møller-Plesset perturbation theory level of theory for use in explicitly correlated (F12) methods, which utilize density fitting for the evaluation of two-electron integrals. Calculations of the correlation energy for a test set of small to medium sized molecules indicate that the density fitting error when using these auxiliary sets is 2 to 3 orders of magnitude smaller than the F12 orbital basis set incompleteness error. The error introduced by the use of these fitting sets within the resolution-of-the-identity approximation of the many-electron integrals arising in F12 theory has also been assessed and is demonstrated to be negligible and well-controlled. General guidelines are proposed for the optimization of density fitting auxiliary basis sets for use with F12 methods for other elements.
Representability of Bloch states on Projector-augmented-wave (PAW) basis sets
NASA Astrophysics Data System (ADS)
Agapito, Luis; Ferretti, Andrea; Curtarolo, Stefano; Buongiorno Nardelli, Marco
2015-03-01
Design of small, yet `complete', localized basis sets is necessary for an efficient dual representation of Bloch states on both plane-wave and localized basis. Such simultaneous dual representation permits the development of faster more accurate (beyond DFT) electronic-structure methods for atomistic materials (e.g. the ACBN0 method.) by benefiting from algorithms (real and reciprocal space) and hardware acceleration (e.g. GPUs) used in the quantum-chemistry and solid-state communities. Finding a `complete' atomic-orbital basis (partial waves) is also a requirement in the generation of robust and transferable PAW pseudopotentials. We have employed the atomic-orbital basis from available PAW data sets, which extends through most of the periodic table, and tested the representability of Bloch states on such basis. Our results show that PAW data sets allow systematic and accurate representability of the PAW Bloch states, better than with traditional quantum-chemistry double-zeta- and double-zeta-polarized-quality basis sets.
Efficient calculation of integrals in mixed ramp-Gaussian basis sets
McKemmish, Laura K.
2015-04-07
Algorithms for the efficient calculation of two-electron integrals in the newly developed mixed ramp-Gaussian basis sets are presented, alongside a Fortran90 implementation of these algorithms, RAMPITUP. These new basis sets have significant potential to (1) give some speed-up (estimated at up to 20% for large molecules in fully optimised code) to general-purpose Hartree-Fock (HF) and density functional theory quantum chemistry calculations, replacing all-Gaussian basis sets, and (2) give very large speed-ups for calculations of core-dependent properties, such as electron density at the nucleus, NMR parameters, relativistic corrections, and total energies, replacing the current use of Slater basis functions or very large specialised all-Gaussian basis sets for these purposes. This initial implementation already demonstrates roughly 10% speed-ups in HF/R-31G calculations compared to HF/6-31G calculations for large linear molecules, demonstrating the promise of this methodology, particularly for the second application. As well as the reduction in the total primitive number in R-31G compared to 6-31G, this timing advantage can be attributed to the significant reduction in the number of mathematically complex intermediate integrals after modelling each ramp-Gaussian basis-function-pair as a sum of ramps on a single atomic centre.
Non-Euclidean basis function based level set segmentation with statistical shape prior.
Ruiz, Esmeralda; Reisert, Marco; Bai, Li
2013-01-01
We present a new framework for image segmentation with statistical shape model enhanced level sets represented as a linear combination of non-Euclidean radial basis functions (RBFs). The shape prior for the level set is represented as a probabilistic map created from the training data and registered with the target image. The new framework has the following advantages: 1) the explicit RBF representation of the level set allows the level set evolution to be represented as ordinary differential equations and reinitialization is no longer required. 2) The non-Euclidean distance RBFs makes it possible to incorporate image information into the basis functions, which results in more accurate and topologically more flexible solutions. Experimental results are presented to demonstrate the advantages of the method, as well as critical analysis of level sets versus the combination of both methods.
On the basis set convergence of electron-electron entanglement measures: helium-like systems.
Hofer, Thomas S
2013-01-01
A systematic investigation of three different electron-electron entanglement measures, namely the von Neumann, the linear and the occupation number entropy at full configuration interaction level has been performed for the four helium-like systems hydride, helium, Li(+) and Be(2+) using a large number of different basis sets. The convergence behavior of the resulting energies and entropies revealed that the latter do in general not show the expected strictly monotonic increase upon increase of the one-electron basis. Overall, the three different entanglement measures show good agreement among each other, the largest deviations being observed for small basis sets. The data clearly demonstrates that it is important to consider the nature of the chemical system when investigating entanglement phenomena in the framework of Gaussian type basis sets: while in case of hydride the use of augmentation functions is crucial, the application of core functions greatly improves the accuracy in case of cationic systems such as Li(+) and Be(2+). In addition, numerical derivatives of the entanglement measures with respect to the nucleic charge have been determined, which proved to be a very sensitive probe of the convergence leading to qualitatively wrong results (i.e., the wrong sign) if too small basis sets are used.
Predicting Pt-195 NMR chemical shift using new relativistic all-electron basis set.
Paschoal, D; Guerra, C Fonseca; de Oliveira, M A L; Ramalho, T C; Dos Santos, H F
2016-10-01
Predicting NMR properties is a valuable tool to assist the experimentalists in the characterization of molecular structure. For heavy metals, such as Pt-195, only a few computational protocols are available. In the present contribution, all-electron Gaussian basis sets, suitable to calculate the Pt-195 NMR chemical shift, are presented for Pt and all elements commonly found as Pt-ligands. The new basis sets identified as NMR-DKH were partially contracted as a triple-zeta doubly polarized scheme with all coefficients obtained from a Douglas-Kroll-Hess (DKH) second-order scalar relativistic calculation. The Pt-195 chemical shift was predicted through empirical models fitted to reproduce experimental data for a set of 183 Pt(II) complexes which NMR sign ranges from -1000 to -6000 ppm. Furthermore, the models were validated using a new set of 75 Pt(II) complexes, not included in the descriptive set. The models were constructed using non-relativistic Hamiltonian at density functional theory (DFT-PBEPBE) level with NMR-DKH basis set for all atoms. For the best model, the mean absolute deviation (MAD) and the mean relative deviation (MRD) were 150 ppm and 6%, respectively, for the validation set (75 Pt-complexes) and 168 ppm (MAD) and 5% (MRD) for all 258 Pt(II) complexes. These results were comparable with relativistic DFT calculation, 200 ppm (MAD) and 6% (MRD). © 2016 Wiley Periodicals, Inc. PMID:27510431
Predicting Pt-195 NMR chemical shift using new relativistic all-electron basis set.
Paschoal, D; Guerra, C Fonseca; de Oliveira, M A L; Ramalho, T C; Dos Santos, H F
2016-10-01
Predicting NMR properties is a valuable tool to assist the experimentalists in the characterization of molecular structure. For heavy metals, such as Pt-195, only a few computational protocols are available. In the present contribution, all-electron Gaussian basis sets, suitable to calculate the Pt-195 NMR chemical shift, are presented for Pt and all elements commonly found as Pt-ligands. The new basis sets identified as NMR-DKH were partially contracted as a triple-zeta doubly polarized scheme with all coefficients obtained from a Douglas-Kroll-Hess (DKH) second-order scalar relativistic calculation. The Pt-195 chemical shift was predicted through empirical models fitted to reproduce experimental data for a set of 183 Pt(II) complexes which NMR sign ranges from -1000 to -6000 ppm. Furthermore, the models were validated using a new set of 75 Pt(II) complexes, not included in the descriptive set. The models were constructed using non-relativistic Hamiltonian at density functional theory (DFT-PBEPBE) level with NMR-DKH basis set for all atoms. For the best model, the mean absolute deviation (MAD) and the mean relative deviation (MRD) were 150 ppm and 6%, respectively, for the validation set (75 Pt-complexes) and 168 ppm (MAD) and 5% (MRD) for all 258 Pt(II) complexes. These results were comparable with relativistic DFT calculation, 200 ppm (MAD) and 6% (MRD). © 2016 Wiley Periodicals, Inc.
Miliordos, Evangelos; Xantheas, Sotiris S.
2015-03-07
We report the variation of the binding energy of the formic acid dimer at the CCSD(T)/ Complete Basis Set limit and examine the validity of the BSSE-correction, previously challenged by Kalescky, Kraka and Cremer [J. Chem. Phys. 140 (2014) 084315]. Our best estimate of D0=14.3±0.1 kcal/mol is in excellent agreement with the experimental value of 14.22±0.12 kcal/mol. The BSSE correction is indeed valid for this system since it exhibits the expected behavior of decreasing with increasing basis set size and its inclusion produces the same limit (within 0.1 kcal/mol) as the one obtained from extrapolation of the uncorrected binding energy. This work was supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences and Biosciences. Pacific Northwest National Laboratory (PNNL) is a multiprogram national laboratory operated for DOE by Battelle. A portion of this research was performed using the Molecular Science Computing Facility (MSCF) in EMSL, a national scientific user facility sponsored by the Department of Energy’s Office of Biological and Environmental Research and located at PNNL.
Molecular Dipole Moments within the Incremental Scheme Using the Domain-Specific Basis-Set Approach.
Fiedler, Benjamin; Coriani, Sonia; Friedrich, Joachim
2016-07-12
We present the first implementation of the fully automated incremental scheme for CCSD unrelaxed dipole moments using the domain-specific basis-set approach. Truncation parameters are varied, and the accuracy of the method is statistically analyzed for a test set of 20 molecules. The local approximations introduce small errors at second order and negligible ones at third order. For a third-order incremental CCSD expansion with a CC2 error correction, a cc-pVDZ/SV domain-specific basis set (tmain = 3.5 Bohr), and the truncation parameter f = 30 Bohr, we obtain a mean error of 0.00 mau (-0.20 mau) and a standard deviation of 1.95 mau (2.17 mau) for the total dipole moments (Cartesian components of the dipole vectors). By analyzing incremental CCSD energies, we demonstrate that the MP2 and CC2 error correction schemes are an exclusive correction for the domain-specific basis-set error. Our implementation of the incremental scheme provides fully automated computations of highly accurate dipole moments at reduced computational cost and is fully parallelized in terms of the calculation of the increments. Therefore, one can utilize the incremental scheme, on the same hardware, to extend the basis set in comparison to standard CCSD and thus obtain a better total accuracy. PMID:27300371
How to spoil a good basis set for Rayleigh-Ritz calculations
Pupyshev, Vladimir I.; Montgomery, H. E. Jr.
2013-08-15
For model quantum mechanical systems such as the harmonic oscillator and a particle in an impenetrable box, we consider the set of exact discrete spectrum functions and define the modified basis set by subtraction of the ground state wavefunction from all the other wavefunctions with some real weights. It is demonstrated that the modified set of functions is complete in the space of square integrable functions if and only if the series of the squared weights diverges. A similar, but nonequivalent criterion is derived for convergence of Rayleigh-Ritz ground state energy calculations to the exact ground state energy value with the basis set extension. Some numerical illustrations are provided which demonstrate a wide variety of possible situations for model systems.
NASA Astrophysics Data System (ADS)
Gidopoulos, Nikitas I.; Lathiotakis, Nektarios N.
2013-10-01
The Comment by Friedrich does not dispute the central result of our paper [Phys. Rev. APLRAAN1050-294710.1103/PhysRevA.85.052508 85, 052508 (2012)] that nonanalytic behavior is present in long-established mathematical pathologies arising in the solution of finite basis optimized effective potential (OEP) equations. In the Comment, the terms “balancing of basis sets” and “basis-set convergence” imply a particular order towards the limit of a large orbital basis sets where the large-orbital-base limit is always taken first, before the large-auxiliary-base limit, until overall convergence is achieved, at a high computational cost. The authors claim that, on physical grounds, this order of limits is not only sufficient, but also necessary in order to avoid the mathematical pathologies. In response to the Comment, we remark that it is already written in our paper that the nonanalyticity trivially disappears with large orbital basis sets. We point out that the authors of the Comment give an incorrect proof of this statement. We also show that the order of limits towards convergence of the potential is immaterial. A recent paper by the authors of the Comment proposes a partial correction for the incomplete orbital basis error in the full-potential linearized augmented-plane-wave method. Similar to the correction developed in our paper, this correction also benefits from an effectively complete orbital basis, even though only a finite orbital basis is employed in the calculation. This shows that it is unnecessary to take, in practice, the limit of an infinite orbital basis in order to avoid mathematical pathologies in the OEP. Our paper is a significant contribution in that direction with general applicability to any choice of basis sets. Finally, contrary to an allusion in the abstract and assertions in the main text of the Comment that unphysical oscillations of the OEP are supposedly attributed to the common energy denominator approximation, in fact, such
Matus, Myrna H; Garza, Jorge; Galván, Marcelo
2004-06-01
In order to study the Kohn-Sham frontier molecular orbital energies in the complete basis limit, a comparative study between localized functions and plane waves, obtained with the local density approximation exchange-correlation functional is made. The analyzed systems are ethylene and butadiene, since they are theoretical and experimentally well characterized. The localized basis sets used are those developed by Dunning. For the plane-waves method, the pseudopotential approximation is employed. The results obtained by the localized basis sets suggest that it is possible to get an estimation of the orbital energies in the limit of the complete basis set, when the basis set size is large. It is shown that the frontier molecular orbital energies and the energy gaps obtained with plane waves are similar to those obtained with a large localized basis set, when the size of the supercell and the plane-wave expansion have been appropriately calibrated.
A Novel Gaussian-Sinc mixed Basis Set for Electronic Structure calculations
NASA Astrophysics Data System (ADS)
Jerke, Jonathan; Lee, Young; Tymczak, C. J.
2015-03-01
A Gaussian-Sinc mixed basis set for the computation of the electronic structure of atoms and molecules is presented. Excellent bases functions are known for ``core'' and ``valence'' separately, such as Gaussians for the ``core'' wave functions and Plane-waves for ``valance'' wave functions, but as yet no method is known that can accurately deal with both regimes in a single basis. A Gaussian-Sinc mixed basis can do both. This method resolves several issues such as: i) the Sincs basis spans the same space as the plane-waves basis, yet are semi-local enough to define all interaction elements including Exchange; ii) the Gaussians span the spherically symmetric core states and can be mixed with the Sinc functions in a computationally efficient methodology; iii) together, this mixed basis set is a flexible, computationally efficient and a highly accurate method for solving atomic and molecular problems. This methodology has been implemented within the Hartree-Fock level of theory within ultra-strong magnetic fields. To demonstrate the utility of this new method, we calculated the ground state Hartree-Fock energies to five digits accuracy in ultra strong magnetic fields for Helium to Neon, Molecular Hydrogen, Water, Carbon dioxide and Benzene. Welch Foundation (Grant J-1675), the ARO (Grant W911Nf-13-1-0162), the Texas Southern University High Performance Computing Center (http:/hpcc.tsu.edu/; Grant PHY-1126251) and NSF-CREST CRCN project (Grant HRD-1137732).
Correlation consistent basis sets for actinides. I. The Th and U atoms
Peterson, Kirk A.
2015-02-21
New correlation consistent basis sets based on both pseudopotential (PP) and all-electron Douglas-Kroll-Hess (DKH) Hamiltonians have been developed from double- to quadruple-zeta quality for the actinide atoms thorium and uranium. Sets for valence electron correlation (5f6s6p6d), cc − pV nZ − PP and cc − pV nZ − DK3, as well as outer-core correlation (valence + 5s5p5d), cc − pwCV nZ − PP and cc − pwCV nZ − DK3, are reported (n = D, T, Q). The -PP sets are constructed in conjunction with small-core, 60-electron PPs, while the -DK3 sets utilized the 3rd-order Douglas-Kroll-Hess scalar relativistic Hamiltonian. Both series of basis sets show systematic convergence towards the complete basis set limit, both at the Hartree-Fock and correlated levels of theory, making them amenable to standard basis set extrapolation techniques. To assess the utility of the new basis sets, extensive coupled cluster composite thermochemistry calculations of ThF{sub n} (n = 2 − 4), ThO{sub 2}, and UF{sub n} (n = 4 − 6) have been carried out. After accurately accounting for valence and outer-core correlation, spin-orbit coupling, and even Lamb shift effects, the final 298 K atomization enthalpies of ThF{sub 4}, ThF{sub 3}, ThF{sub 2}, and ThO{sub 2} are all within their experimental uncertainties. Bond dissociation energies of ThF{sub 4} and ThF{sub 3}, as well as UF{sub 6} and UF{sub 5}, were similarly accurate. The derived enthalpies of formation for these species also showed a very satisfactory agreement with experiment, demonstrating that the new basis sets allow for the use of accurate composite schemes just as in molecular systems composed only of lighter atoms. The differences between the PP and DK3 approaches were found to increase with the change in formal oxidation state on the actinide atom, approaching 5-6 kcal/mol for the atomization enthalpies of ThF{sub 4} and ThO{sub 2}. The DKH3 atomization energy of ThO{sub 2} was calculated to be smaller than the DKH2
Relativistic correlating basis sets for lanthanide atoms from Ce to Lu.
Sekiya, Masahiro; Noro, Takeshi; Miyoshi, Eisaku; Osanai, You; Koga, Toshikatsu
2006-03-01
Contracted Gaussian-type function (CGTF) sets for the description of the 4f subshell correlation and of the 6s and 5d subshell correlation are developed for lanthanide atoms from Ce to Yb. Also prepared are basis sets for the 5d orbitals, which are vacant in the ground states of most lanthanide atoms but are essential in molecular environments. In addition, correlating CGTF sets for the 4f subshell correlation are supplemented for the Lu atom. A segmented contraction scheme is employed for their compactness and efficiency. Contraction coefficients and exponents are determined by minimizing the deviation from accurate natural orbitals generated from configuration interaction calculations that include relativistic effects through the third-order Douglas-Kroll approximation. All-electron and model core potential calculations with the present correlating sets are performed on the ground state of the diatomic CeO molecule. The calculated spectroscopic constants are in good agreement with experimental values. PMID:16419148
Method and Basis Set Analysis of Oxorhenium(V) Complexes for Theoretical Calculations
Demoin, Dustin Wayne; Li, Yawen; Jurisson, Silvia S.; Deakyne, Carol A.
2012-01-01
A variety of method and basis set combinations has been evaluated for monooxorhenium(V) complexes with N, O, P, S, Cl, and Se donor atoms. The geometries and energies obtained are compared to both high-level computations and literature structures. These calculations show that the PBE0 method outperforms the B3LYP method with respect to both structure and energetics. The combination of 6-31G** basis set on the nonmetal atoms and LANL2TZ effective core potential on the rhenium center gives reliable equilibrium structures with minimal computational resources for both model and literature compounds. Single-point energy calculations at the PBE0/LANL2TZ,6-311+G* level of theory are recommended for energetics. PMID:23087847
Geminal embedding scheme for optimal atomic basis set construction in correlated calculations
Sorella, S.; Devaux, N.; Dagrada, M.; Mazzola, G.; Casula, M.
2015-12-28
We introduce an efficient method to construct optimal and system adaptive basis sets for use in electronic structure and quantum Monte Carlo calculations. The method is based on an embedding scheme in which a reference atom is singled out from its environment, while the entire system (atom and environment) is described by a Slater determinant or its antisymmetrized geminal power (AGP) extension. The embedding procedure described here allows for the systematic and consistent contraction of the primitive basis set into geminal embedded orbitals (GEOs), with a dramatic reduction of the number of variational parameters necessary to represent the many-body wave function, for a chosen target accuracy. Within the variational Monte Carlo method, the Slater or AGP part is determined by a variational minimization of the energy of the whole system in presence of a flexible and accurate Jastrow factor, representing most of the dynamical electronic correlation. The resulting GEO basis set opens the way for a fully controlled optimization of many-body wave functions in electronic structure calculation of bulk materials, namely, containing a large number of electrons and atoms. We present applications on the water molecule, the volume collapse transition in cerium, and the high-pressure liquid hydrogen.
Tesch, Carmen M; de Vivie-Riedle, Regina
2004-12-22
The phase of quantum gates is one key issue for the implementation of quantum algorithms. In this paper we first investigate the phase evolution of global molecular quantum gates, which are realized by optimally shaped femtosecond laser pulses. The specific laser fields are calculated using the multitarget optimal control algorithm, our modification of the optimal control theory relevant for application in quantum computing. As qubit system we use vibrational modes of polyatomic molecules, here the two IR-active modes of acetylene. Exemplarily, we present our results for a Pi gate, which shows a strong dependence on the phase, leading to a significant decrease in quantum yield. To correct for this unwanted behavior we include pressure on the quantum phase in our multitarget approach. In addition the accuracy of these phase corrected global quantum gates is enhanced. Furthermore we could show that in our molecular approach phase corrected quantum gates and basis set independence are directly linked. Basis set independence is also another property highly required for the performance of quantum algorithms. By realizing the Deutsch-Jozsa algorithm in our two qubit molecular model system, we demonstrate the good performance of our phase corrected and basis set independent quantum gates.
Choi, Sunghwan; Hong, Kwangwoo; Kim, Jaewook; Kim, Woo Youn
2015-03-07
We developed a self-consistent field program based on Kohn-Sham density functional theory using Lagrange-sinc functions as a basis set and examined its numerical accuracy for atoms and molecules through comparison with the results of Gaussian basis sets. The result of the Kohn-Sham inversion formula from the Lagrange-sinc basis set manifests that the pseudopotential method is essential for cost-effective calculations. The Lagrange-sinc basis set shows faster convergence of the kinetic and correlation energies of benzene as its size increases than the finite difference method does, though both share the same uniform grid. Using a scaling factor smaller than or equal to 0.226 bohr and pseudopotentials with nonlinear core correction, its accuracy for the atomization energies of the G2-1 set is comparable to all-electron complete basis set limits (mean absolute deviation ≤1 kcal/mol). The same basis set also shows small mean absolute deviations in the ionization energies, electron affinities, and static polarizabilities of atoms in the G2-1 set. In particular, the Lagrange-sinc basis set shows high accuracy with rapid convergence in describing density or orbital changes by an external electric field. Moreover, the Lagrange-sinc basis set can readily improve its accuracy toward a complete basis set limit by simply decreasing the scaling factor regardless of systems.
Choi, Sunghwan; Hong, Kwangwoo; Kim, Jaewook; Kim, Woo Youn
2015-03-01
We developed a self-consistent field program based on Kohn-Sham density functional theory using Lagrange-sinc functions as a basis set and examined its numerical accuracy for atoms and molecules through comparison with the results of Gaussian basis sets. The result of the Kohn-Sham inversion formula from the Lagrange-sinc basis set manifests that the pseudopotential method is essential for cost-effective calculations. The Lagrange-sinc basis set shows faster convergence of the kinetic and correlation energies of benzene as its size increases than the finite difference method does, though both share the same uniform grid. Using a scaling factor smaller than or equal to 0.226 bohr and pseudopotentials with nonlinear core correction, its accuracy for the atomization energies of the G2-1 set is comparable to all-electron complete basis set limits (mean absolute deviation ≤1 kcal/mol). The same basis set also shows small mean absolute deviations in the ionization energies, electron affinities, and static polarizabilities of atoms in the G2-1 set. In particular, the Lagrange-sinc basis set shows high accuracy with rapid convergence in describing density or orbital changes by an external electric field. Moreover, the Lagrange-sinc basis set can readily improve its accuracy toward a complete basis set limit by simply decreasing the scaling factor regardless of systems.
NASA Astrophysics Data System (ADS)
Mao, Yuezhi; Horn, Paul R.; Mardirossian, Narbe; Head-Gordon, Teresa; Skylaris, Chris-Kriton; Head-Gordon, Martin
2016-07-01
Recently developed density functionals have good accuracy for both thermochemistry (TC) and non-covalent interactions (NC) if very large atomic orbital basis sets are used. To approach the basis set limit with potentially lower computational cost, a new self-consistent field (SCF) scheme is presented that employs minimal adaptive basis (MAB) functions. The MAB functions are optimized on each atomic site by minimizing a surrogate function. High accuracy is obtained by applying a perturbative correction (PC) to the MAB calculation, similar to dual basis approaches. Compared to exact SCF results, using this MAB-SCF (PC) approach with the same large target basis set produces <0.15 kcal/mol root-mean-square deviations for most of the tested TC datasets, and <0.1 kcal/mol for most of the NC datasets. The performance of density functionals near the basis set limit can be even better reproduced. With further improvement to its implementation, MAB-SCF (PC) is a promising lower-cost substitute for conventional large-basis calculations as a method to approach the basis set limit of modern density functionals.
Mao, Yuezhi; Horn, Paul R; Mardirossian, Narbe; Head-Gordon, Teresa; Skylaris, Chris-Kriton; Head-Gordon, Martin
2016-07-28
Recently developed density functionals have good accuracy for both thermochemistry (TC) and non-covalent interactions (NC) if very large atomic orbital basis sets are used. To approach the basis set limit with potentially lower computational cost, a new self-consistent field (SCF) scheme is presented that employs minimal adaptive basis (MAB) functions. The MAB functions are optimized on each atomic site by minimizing a surrogate function. High accuracy is obtained by applying a perturbative correction (PC) to the MAB calculation, similar to dual basis approaches. Compared to exact SCF results, using this MAB-SCF (PC) approach with the same large target basis set produces <0.15 kcal/mol root-mean-square deviations for most of the tested TC datasets, and <0.1 kcal/mol for most of the NC datasets. The performance of density functionals near the basis set limit can be even better reproduced. With further improvement to its implementation, MAB-SCF (PC) is a promising lower-cost substitute for conventional large-basis calculations as a method to approach the basis set limit of modern density functionals. PMID:27475350
Mao, Yuezhi; Horn, Paul R; Mardirossian, Narbe; Head-Gordon, Teresa; Skylaris, Chris-Kriton; Head-Gordon, Martin
2016-07-28
Recently developed density functionals have good accuracy for both thermochemistry (TC) and non-covalent interactions (NC) if very large atomic orbital basis sets are used. To approach the basis set limit with potentially lower computational cost, a new self-consistent field (SCF) scheme is presented that employs minimal adaptive basis (MAB) functions. The MAB functions are optimized on each atomic site by minimizing a surrogate function. High accuracy is obtained by applying a perturbative correction (PC) to the MAB calculation, similar to dual basis approaches. Compared to exact SCF results, using this MAB-SCF (PC) approach with the same large target basis set produces <0.15 kcal/mol root-mean-square deviations for most of the tested TC datasets, and <0.1 kcal/mol for most of the NC datasets. The performance of density functionals near the basis set limit can be even better reproduced. With further improvement to its implementation, MAB-SCF (PC) is a promising lower-cost substitute for conventional large-basis calculations as a method to approach the basis set limit of modern density functionals.
Hellweg, Arnim; Rappoport, Dmitrij
2015-01-14
We report optimized auxiliary basis sets for use with the Karlsruhe segmented contracted basis sets including moderately diffuse basis functions (Rappoport and Furche, J. Chem. Phys., 2010, 133, 134105) in resolution-of-the-identity (RI) post-self-consistent field (post-SCF) computations for the elements H-Rn (except lanthanides). The errors of the RI approximation using optimized auxiliary basis sets are analyzed on a comprehensive test set of molecules containing the most common oxidation states of each element and do not exceed those of the corresponding unaugmented basis sets. During these studies an unsatisfying performance of the def2-SVP and def2-QZVPP auxiliary basis sets for Barium was found and improved sets are provided. We establish the versatility of the def2-SVPD, def2-TZVPPD, and def2-QZVPPD basis sets for RI-MP2 and RI-CC (coupled-cluster) energy and property calculations. The influence of diffuse basis functions on correlation energy, basis set superposition error, atomic electron affinity, dipole moments, and computational timings is evaluated at different levels of theory using benchmark sets and showcase examples.
Relativistic correlating basis sets for actinide atoms from 90Th to 103Lr.
Noro, Takeshi; Sekiya, Masahiro; Osanai, You; Koga, Toshikatsu; Matsuyama, Hisashi
2007-12-01
For 14 actinide atoms from (90)Th to (103)Lr, contracted Gaussian-type function sets are developed for the description of correlations of the 5f, 6d, and 7s electrons. Basis sets for the 6d orbitals are also prepared, since the orbitals are important in molecular environments despite their vacancy in the ground state of some actinides. A segmented contraction scheme is employed for the compactness and efficiency. Contraction coefficients and exponents are so determined as to minimize the deviation from accurate natural orbitals of the lowest term arising from the 5f(n-1)6d(1)7s(2) configuration. The spin-free relativistic effects are considered through the third-order Douglas-Kroll approximation. To test the present correlating sets, all-electron calculations are performed on the ground state of (90)ThO molecule. The calculated spectroscopic constants are in excellent agreement with experimental values.
Ghost transmission: How large basis sets can make electron transport calculations worse
Herrmann, Carmen; Solomon, Gemma C.; Subotnik, Joseph E.; Mujica, Vladimiro; Ratner, Mark A.
2010-01-01
The Landauer approach has proven to be an invaluable tool for calculating the electron transport properties of single molecules, especially when combined with a nonequilibrium Green’s function approach and Kohn–Sham density functional theory. However, when using large nonorthogonal atom-centered basis sets, such as those common in quantum chemistry, one can find erroneous results if the Landauer approach is applied blindly. In fact, basis sets of triple-zeta quality or higher sometimes result in an artificially high transmission and possibly even qualitatively wrong conclusions regarding chemical trends. In these cases, transport persists when molecular atoms are replaced by basis functions alone (“ghost atoms”). The occurrence of such ghost transmission is correlated with low-energy virtual molecular orbitals of the central subsystem and may be interpreted as a biased and thus inaccurate description of vacuum transmission. An approximate practical correction scheme is to calculate the ghost transmission and subtract it from the full transmission. As a further consequence of this study, it is recommended that sensitive molecules be used for parameter studies, in particular those whose transmission functions show antiresonance features such as benzene-based systems connected to the electrodes in meta positions and other low-conducting systems such as alkanes and silanes.
Computation of two-electron screened Coulomb potential integrals in Hylleraas basis sets
NASA Astrophysics Data System (ADS)
Jiao, Li Guang; Ho, Yew Kam
2015-03-01
The Gegenbauer expansion and Taylor expansion methods are developed to accurately and efficiently calculate the two-electron screened Coulomb potential integrals in Hylleraas basis sets. The combination of these two methods covers the entire parameter space of the integrals, including arbitrary total angular momenta, two-electron configurations, powers of inter-electronic coordinate, and complex screening parameters. Numerical examples are given and comparisons with other computational methods in some restricted situations are made. The present methods can be easily applied to calculate the bound and resonant states of two-electron atoms or exotic three-body systems embedded in the screening environment by using the Hylleraas or Hylleraas-CI basis functions.
Grimme, Stefan; Brandenburg, Jan Gerit; Bannwarth, Christoph; Hansen, Andreas
2015-08-01
A density functional theory (DFT) based composite electronic structure approach is proposed to efficiently compute structures and interaction energies in large chemical systems. It is based on the well-known and numerically robust Perdew-Burke-Ernzerhoff (PBE) generalized-gradient-approximation in a modified global hybrid functional with a relatively large amount of non-local Fock-exchange. The orbitals are expanded in Ahlrichs-type valence-double zeta atomic orbital (AO) Gaussian basis sets, which are available for many elements. In order to correct for the basis set superposition error (BSSE) and to account for the important long-range London dispersion effects, our well-established atom-pairwise potentials are used. In the design of the new method, particular attention has been paid to an accurate description of structural parameters in various covalent and non-covalent bonding situations as well as in periodic systems. Together with the recently proposed three-fold corrected (3c) Hartree-Fock method, the new composite scheme (termed PBEh-3c) represents the next member in a hierarchy of "low-cost" electronic structure approaches. They are mainly free of BSSE and account for most interactions in a physically sound and asymptotically correct manner. PBEh-3c yields good results for thermochemical properties in the huge GMTKN30 energy database. Furthermore, the method shows excellent performance for non-covalent interaction energies in small and large complexes. For evaluating its performance on equilibrium structures, a new compilation of standard test sets is suggested. These consist of small (light) molecules, partially flexible, medium-sized organic molecules, molecules comprising heavy main group elements, larger systems with long bonds, 3d-transition metal systems, non-covalently bound complexes (S22 and S66×8 sets), and peptide conformations. For these sets, overall deviations from accurate reference data are smaller than for various other tested DFT methods
NASA Astrophysics Data System (ADS)
Grimme, Stefan; Brandenburg, Jan Gerit; Bannwarth, Christoph; Hansen, Andreas
2015-08-01
A density functional theory (DFT) based composite electronic structure approach is proposed to efficiently compute structures and interaction energies in large chemical systems. It is based on the well-known and numerically robust Perdew-Burke-Ernzerhoff (PBE) generalized-gradient-approximation in a modified global hybrid functional with a relatively large amount of non-local Fock-exchange. The orbitals are expanded in Ahlrichs-type valence-double zeta atomic orbital (AO) Gaussian basis sets, which are available for many elements. In order to correct for the basis set superposition error (BSSE) and to account for the important long-range London dispersion effects, our well-established atom-pairwise potentials are used. In the design of the new method, particular attention has been paid to an accurate description of structural parameters in various covalent and non-covalent bonding situations as well as in periodic systems. Together with the recently proposed three-fold corrected (3c) Hartree-Fock method, the new composite scheme (termed PBEh-3c) represents the next member in a hierarchy of "low-cost" electronic structure approaches. They are mainly free of BSSE and account for most interactions in a physically sound and asymptotically correct manner. PBEh-3c yields good results for thermochemical properties in the huge GMTKN30 energy database. Furthermore, the method shows excellent performance for non-covalent interaction energies in small and large complexes. For evaluating its performance on equilibrium structures, a new compilation of standard test sets is suggested. These consist of small (light) molecules, partially flexible, medium-sized organic molecules, molecules comprising heavy main group elements, larger systems with long bonds, 3d-transition metal systems, non-covalently bound complexes (S22 and S66×8 sets), and peptide conformations. For these sets, overall deviations from accurate reference data are smaller than for various other tested DFT methods
Grimme, Stefan Brandenburg, Jan Gerit; Bannwarth, Christoph; Hansen, Andreas
2015-08-07
A density functional theory (DFT) based composite electronic structure approach is proposed to efficiently compute structures and interaction energies in large chemical systems. It is based on the well-known and numerically robust Perdew-Burke-Ernzerhoff (PBE) generalized-gradient-approximation in a modified global hybrid functional with a relatively large amount of non-local Fock-exchange. The orbitals are expanded in Ahlrichs-type valence-double zeta atomic orbital (AO) Gaussian basis sets, which are available for many elements. In order to correct for the basis set superposition error (BSSE) and to account for the important long-range London dispersion effects, our well-established atom-pairwise potentials are used. In the design of the new method, particular attention has been paid to an accurate description of structural parameters in various covalent and non-covalent bonding situations as well as in periodic systems. Together with the recently proposed three-fold corrected (3c) Hartree-Fock method, the new composite scheme (termed PBEh-3c) represents the next member in a hierarchy of “low-cost” electronic structure approaches. They are mainly free of BSSE and account for most interactions in a physically sound and asymptotically correct manner. PBEh-3c yields good results for thermochemical properties in the huge GMTKN30 energy database. Furthermore, the method shows excellent performance for non-covalent interaction energies in small and large complexes. For evaluating its performance on equilibrium structures, a new compilation of standard test sets is suggested. These consist of small (light) molecules, partially flexible, medium-sized organic molecules, molecules comprising heavy main group elements, larger systems with long bonds, 3d-transition metal systems, non-covalently bound complexes (S22 and S66×8 sets), and peptide conformations. For these sets, overall deviations from accurate reference data are smaller than for various other tested DFT
NASA Astrophysics Data System (ADS)
Woody, M. C.; Arunachalam, S.; Binkowski, F.; West, J.; Jathar, S.; Robinson, A. L.
2012-12-01
Regional air quality studies aimed at quantifying the impacts of aviation emissions to PM2.5 have generally predicted relatively low contributions from organic aerosols. However, recent sampling and smog chamber experiments have suggested that organic aerosols comprise a significant fraction of total PM2.5 formed from aircraft emissions. In this study, the results of aircraft-specific sampling and smog chamber experiments are incorporated into a regional chemical transport model with the volatility basis set and used to predict organic aerosol contributions from aircraft emissions. Contributions of aircraft emissions to primary organic aerosols (POA), secondary organic aerosols (SOA) formed from traditional precursors (e.g. aromatics and long-chain alkanes), and non-traditional SOA formed from unidentified precursors previously unaccounted for in air quality models are modeled using the volatility basis set approach in CMAQ v4.7.1. The model includes oxidation reactions of traditional SOA (both biogenic and anthropogenic) and non-traditional SOA precursors (specific to aircraft emissions) with OH to produce products of lower volatility. Non-traditional SOA yields and precursor emission estimates for idle and non-idle aircraft activities are based on sampling and smog chamber experiments. This model predicts the organic aerosol and total PM2.5 concentrations formed from aircraft emissions due to landing and takeoff activities at the Hartsfield-Jackson International Airport in Atlanta during January and July, 2002. Overall model results are compared against monitoring data in the region to determine the impacts of using the volatility basis set on CMAQ model performance.
Correlation consistent basis sets for lanthanides: The atoms La-Lu
NASA Astrophysics Data System (ADS)
Lu, Qing; Peterson, Kirk A.
2016-08-01
Using the 3rd-order Douglas-Kroll-Hess (DKH3) Hamiltonian, all-electron correlation consistent basis sets of double-, triple-, and quadruple-zeta quality have been developed for the lanthanide elements La through Lu. Basis sets designed for the recovery of valence correlation (defined here as 4f5s5p5d6s), cc-pVnZ-DK3, and outer-core correlation (valence + 4s4p4d), cc-pwCVnZ-DK3, are reported (n = D, T, and Q). Systematic convergence of both Hartree-Fock and correlation energies towards their respective complete basis set (CBS) limits are observed. Benchmark calculations of the first three ionization potentials (IPs) of La through Lu are reported at the DKH3 coupled cluster singles and doubles with perturbative triples, CCSD(T), level of theory, including effects of correlation down through the 4s electrons. Spin-orbit coupling is treated at the 2-component HF level. After extrapolation to the CBS limit, the average errors with respect to experiment were just 0.52, 1.14, and 4.24 kcal/mol for the 1st, 2nd, and 3rd IPs, respectively, compared to the average experimental uncertainties of 0.03, 1.78, and 2.65 kcal/mol, respectively. The new basis sets are also used in CCSD(T) benchmark calculations of the equilibrium geometries, atomization energies, and heats of formation for Gd2, GdF, and GdF3. Except for the equilibrium geometry and harmonic frequency of GdF, which are accurately known from experiment, all other calculated quantities represent significant improvements compared to the existing experimental quantities. With estimated uncertainties of about ±3 kcal/mol, the 0 K atomization energies (298 K heats of formation) are calculated to be (all in kcal/mol): 33.2 (160.1) for Gd2, 151.7 (-36.6) for GdF, and 447.1 (-295.2) for GdF3.
NASA Astrophysics Data System (ADS)
Martins, L. S. C.; Jorge, F. E.; Machado, S. F.
2015-11-01
All-electron contracted Gaussian basis set of triple zeta valence quality plus polarisation functions (TZP) for the elements Cs, Ba, La, and from Hf to Rn is presented. Douglas-Kroll-Hess (DKH) basis set for fifth-row elements is also reported. We have recontracted the original TZP basis set, i.e., the values of the contraction coefficients are re-optimised using the second-order DKH Hamiltonian. By addition of diffuse functions (s, p, d, f, and g symmetries), which are optimised for the anion ground states, an augmented TZP basis set is constructed. Using the B3LYP hybrid functional, the performance of the TZP-DKH basis set is assessed for predicting atomic ionisation energy as well as spectroscopy constants of some compounds. Despite its compact size, this set demonstrates consistent, efficient, and reliable performance and will be especially useful in calculations of molecular properties that require explicit treatment of the core electrons.
Roscioni, Otello M; Lee, Edmond P F; Dyke, John M
2012-10-01
We present a set of effective core potential (ECP) basis sets for rhodium atoms which are of reasonable size for use in electronic structure calculations. In these ECP basis sets, the Los Alamos ECP is used to simulate the effect of the core electrons while an optimized set of Gaussian functions, which includes polarization and diffuse functions, is used to describe the valence electrons. These basis sets were optimized to reproduce the ionization energy and electron affinity of atomic rhodium. They were also tested by computing the electronic ground state geometry and harmonic frequencies of [Rh(CO)(2) μ-Cl](2) , Rh(CO)(2) ClPy, and RhCO (neutral and its positive, and negative ions) as well as the enthalpy of the reaction of [Rh(CO)(2) μ-Cl](2) with pyridine (Py) to give Rh(CO)(2) ClPy, at different levels of theory. Good agreement with experimental values was obtained. Although the number of basis functions used in our ECP basis sets is smaller than those of other ECP basis sets of comparable quality, we show that the newly developed ECP basis sets provide the flexibility and precision required to reproduce a wide range of chemical and physical properties of rhodium compounds. Therefore, we recommend the use of these compact yet accurate ECP basis sets for electronic structure calculations on molecules involving rhodium atoms.
Ideal basis sets for the Dirac Coulomb problem: Eigenvalue bounds and convergence proofs
NASA Astrophysics Data System (ADS)
Munger, Charles Thomas
2007-02-01
Basis sets are developed for the Dirac Coulomb Hamiltonian for which the resulting numerical eigenvalues and eigenfunctions are proved mathematically to have all the following properties: to converge to the exact eigenfunctions and eigenvalues, with necessary and sufficient conditions for convergence being known; to have neither missing nor spurious states; to maintain the Coulomb symmetries between eigenvalues and eigenfunctions of the opposite sign of the Dirac quantum number κ; to have positive eigenvalues bounded from below by the corresponding exact eigenvalues; and to have negative eigenvalues bounded from above by -mc2. All these properties are maintained using functions that may be analytic or nonanalytic (e.g., Slater functions or splines); that match the noninteger power dependence of the exact eigenfunctions at the origin, or that do not; or that extend to +∞ as do the exact eigenfunctions, or that vanish outside a cavity of large radius R (convergence then occurring after a second limit, R →∞). The same basis sets can be used without modification for potentials other than the Coulomb, such as the potential of a finite distribution of nuclear charge, or a screened Coulomb potential; the error in a numerical eigenvalue is shown to be second order in the departure of the potential from the Coulomb. In certain bases of Sturmian functions the numerical eigenvalues can be related to the zeros of the Pollaczek polynomials.
Many-body calculations of molecular electric polarizabilities in asymptotically complete basis sets
NASA Astrophysics Data System (ADS)
Monten, Ruben; Hajgató, Balázs; Deleuze, Michael S.
2011-10-01
The static dipole polarizabilities of Ne, CO, N2, F2, HF, H2O, HCN, and C2H2 (acetylene) have been determined close to the Full-CI limit along with an asymptotically complete basis set (CBS), according to the principles of a Focal Point Analysis. For this purpose the results of Finite Field calculations up to the level of Coupled Cluster theory including Single, Double, Triple, Quadruple and perturbative Pentuple excitations [CCSDTQ(P)] were used, in conjunction with suited extrapolations of energies obtained using augmented and doubly-augmented Dunning's correlation consistent polarized valence basis sets of improving quality. The polarizability characteristics of C2H4 (ethylene) and C2H6 (ethane) have been determined on the same grounds at the CCSDTQ level in the CBS limit. Comparison is made with results obtained using lower levels in electronic correlation, or taking into account the relaxation of the molecular structure due to an adiabatic polarization process. Vibrational corrections to electronic polarizabilities have been empirically estimated according to Born-Oppenheimer Molecular Dynamical simulations employing Density Functional Theory. Confrontation with experiment ultimately indicates relative accuracies of the order of 1 to 2%.
Analytic basis set for high-Z atomic QED calculations: Heavy He-like ions
Hylton, D.J.; Snyderman, N.J.
1997-04-01
A relativistic Sturmian analytic basis set representation for the Coulomb-Dirac Green function, previously studied by Zapryagaev, Manakov, and Pal{close_quote}chikov [Opt. Spectrosc. {bold 52}, 248 (1982)], is investigated for application to high-Z atomic QED calculations. This pseudoeigenfunction representation follows from exact identities starting from the Whittaker function representation. It eliminates the radial ordering problem of that representation, and so is particularly useful for numerical calculation of the perturbation theory Feynman diagrams with more than one electron Green function. While the Green function represents discrete bound states, and both positive and negative energy continuum states, the Sturmian (bound-state-like) form for the pseudoeigenfunctions makes it possible to more analytically calculate matrix elements for full photon exchange, reducing numerical problems for high photon frequency. For He-like Fm (Z=100) we calculate the perturbation theory equivalent of the Dirac-Fock-Breit ground-state energy, agreeing well with the Grant code and with the numerical B-spline basis set approach results of Blundell, Mohr, Johnson, and Sapirstein [Phys. Rev. A {bold 48}, 2615 (1993)]. Preliminary results on the relativistic and QED correlation are also reported. {copyright} {ital 1997} {ital The American Physical Society}
Green's function multiple-scattering theory with a truncated basis set: An augmented-KKR formalism
Alam, Aftab; Khan, Suffian N.; Smirnov, A. V.; Nicholson, D. M.; Johnson, Duane D.
2014-11-04
Korringa-Kohn-Rostoker (KKR) Green's function, multiple-scattering theory is an ecient sitecentered, electronic-structure technique for addressing an assembly of N scatterers. Wave-functions are expanded in a spherical-wave basis on each scattering center and indexed up to a maximum orbital and azimuthal number Lmax = (l,m)max, while scattering matrices, which determine spectral properties, are truncated at Ltr = (l,m)tr where phase shifts δl>ltr are negligible. Historically, Lmax is set equal to Ltr, which is correct for large enough Lmax but not computationally expedient; a better procedure retains higher-order (free-electron and single-site) contributions for Lmax > Ltr with δl>ltr set to zero [Zhang andmore » Butler, Phys. Rev. B 46, 7433]. We present a numerically ecient and accurate augmented-KKR Green's function formalism that solves the KKR equations by exact matrix inversion [R3 process with rank N(ltr + 1)2] and includes higher-L contributions via linear algebra [R2 process with rank N(lmax +1)2]. Augmented-KKR approach yields properly normalized wave-functions, numerically cheaper basis-set convergence, and a total charge density and electron count that agrees with Lloyd's formula. We apply our formalism to fcc Cu, bcc Fe and L10 CoPt, and present the numerical results for accuracy and for the convergence of the total energies, Fermi energies, and magnetic moments versus Lmax for a given Ltr.« less
Green's function multiple-scattering theory with a truncated basis set: An augmented-KKR formalism
Alam, Aftab; Khan, Suffian N.; Smirnov, A. V.; Nicholson, D. M.; Johnson, Duane D.
2014-11-04
Korringa-Kohn-Rostoker (KKR) Green's function, multiple-scattering theory is an ecient sitecentered, electronic-structure technique for addressing an assembly of N scatterers. Wave-functions are expanded in a spherical-wave basis on each scattering center and indexed up to a maximum orbital and azimuthal number L_{max} = (l,m)_{max}, while scattering matrices, which determine spectral properties, are truncated at L_{tr} = (l,m)_{tr} where phase shifts δl>l_{tr} are negligible. Historically, L_{max} is set equal to L_{tr}, which is correct for large enough L_{max} but not computationally expedient; a better procedure retains higher-order (free-electron and single-site) contributions for L_{max} > L_{tr} with δl>l_{tr} set to zero [Zhang and Butler, Phys. Rev. B 46, 7433]. We present a numerically ecient and accurate augmented-KKR Green's function formalism that solves the KKR equations by exact matrix inversion [R^{3} process with rank N(l_{tr} + 1)^{2}] and includes higher-L contributions via linear algebra [R^{2} process with rank N(l_{max} +1)^{2}]. Augmented-KKR approach yields properly normalized wave-functions, numerically cheaper basis-set convergence, and a total charge density and electron count that agrees with Lloyd's formula. We apply our formalism to fcc Cu, bcc Fe and L1_{0} CoPt, and present the numerical results for accuracy and for the convergence of the total energies, Fermi energies, and magnetic moments versus L_{max} for a given L_{tr}.
NASA Astrophysics Data System (ADS)
Abrams, Micah L.; Sherrill, C. David
2003-01-01
We compare several standard polarized double-zeta basis sets for use in full configuration interaction benchmark computations. The 6-31G**, DZP, cc-pVDZ, and Widmark-Malmqvist-Roos atomic natural orbital (ANO) basis sets are assessed on the basis of their ability to provide accurate full configuration interaction spectroscopic constants for several small molecules. Even though highly correlated methods work best with larger basis sets, predicted spectroscopic constants are in good agreement with experiment; bond lengths and harmonic vibrational frequencies have average absolute errors no larger than 0.017 Å and 1.6%, respectively, for all but the ANO basis. For the molecules considered, 6-31G** gives the smallest average errors, while the ANO basis set gives the largest. The use of variationally optimized basis sets and natural orbitals are also explored for improved benchmarking. Although optimized basis sets do not always improve predictions of molecular properties, taking a DZP-sized subset of the natural orbitals from a singles and doubles configuration interaction computation in a larger basis significantly improves results.
Analysis of cornea curvature using radial basis functions - Part II: Fitting to data-set.
Griffiths, G W; Płociniczak, Ł; Schiesser, W E
2016-10-01
In part I we discussed the solution of corneal curvature using a 2D meshless method based on radial basis functions (RBFs). In Part II we use these methods to fit a full nonlinear thin membrane model to a measured data-set in order to generate a topological mathematical description of the cornea. In addition, we show how these results can lead to estimations for corneal radius of curvature and certain physical properties of the cornea; namely, tension and elasticity coefficient. Again all calculations and graphics generation were performed using the R language programming environment. The model describes corneal topology extremely well, and the estimated properties fall well within the expected range of values. The method is straight forward to implement and offers scope for further analysis using more detailed 3D models that include corneal thickness. PMID:27570056
NASA Astrophysics Data System (ADS)
Rohmer, Jeremy
2016-04-01
Predicting the temporal evolution of landslides is typically supported by numerical modelling. Dynamic sensitivity analysis aims at assessing the influence of the landslide properties on the time-dependent predictions (e.g., time series of landslide displacements). Yet two major difficulties arise: 1. Global sensitivity analysis require running the landslide model a high number of times (> 1000), which may become impracticable when the landslide model has a high computation time cost (> several hours); 2. Landslide model outputs are not scalar, but function of time, i.e. they are n-dimensional vectors with n usually ranging from 100 to 1000. In this article, I explore the use of a basis set expansion, such as principal component analysis, to reduce the output dimensionality to a few components, each of them being interpreted as a dominant mode of variation in the overall structure of the temporal evolution. The computationally intensive calculation of the Sobol' indices for each of these components are then achieved through meta-modelling, i.e. by replacing the landslide model by a "costless-to-evaluate" approximation (e.g., a projection pursuit regression model). The methodology combining "basis set expansion - meta-model - Sobol' indices" is then applied to the La Frasse landslide to investigate the dynamic sensitivity analysis of the surface horizontal displacements to the slip surface properties during the pore pressure changes. I show how to extract information on the sensitivity of each main modes of temporal behaviour using a limited number (a few tens) of long running simulations. In particular, I identify the parameters, which trigger the occurrence of a turning point marking a shift between a regime of low values of landslide displacements and one of high values.
NASA Astrophysics Data System (ADS)
Hsu, Po Jen; Lai, S. K.; Rapallo, Arnaldo
2014-03-01
Improved basis sets for the study of polymer dynamics by means of the diffusion theory, and tests on a melt of cis-1,4-polyisoprene decamers, and a toluene solution of a 71-mer syndiotactic trans-1,2-polypentadiene were presented recently [R. Gaspari and A. Rapallo, J. Chem. Phys. 128, 244109 (2008)]. The proposed hybrid basis approach (HBA) combined two techniques, the long time sorting procedure and the maximum correlation approximation. The HBA takes advantage of the strength of these two techniques, and its basis sets proved to be very effective and computationally convenient in describing both local and global dynamics in cases of flexible synthetic polymers where the repeating unit is a unique type of monomer. The question then arises if the same efficacy continues when the HBA is applied to polymers of different monomers, variable local stiffness along the chain and with longer persistence length, which have different local and global dynamical properties against the above-mentioned systems. Important examples of this kind of molecular chains are the proteins, so that a fragment of the protein transthyretin is chosen as the system of the present study. This peptide corresponds to a sequence that is structured in β-sheets of the protein and is located on the surface of the channel with thyroxin. The protein transthyretin forms amyloid fibrils in vivo, whereas the peptide fragment has been shown [C. P. Jaroniec, C. E. MacPhee, N. S. Astrof, C. M. Dobson, and R. G. Griffin, Proc. Natl. Acad. Sci. U.S.A. 99, 16748 (2002)] to form amyloid fibrils in vitro in extended β-sheet conformations. For these reasons the latter is given considerable attention in the literature and studied also as an isolated fragment in water solution where both experimental and theoretical efforts have indicated the propensity of the system to form β turns or α helices, but is otherwise predominantly unstructured. Differing from previous computational studies that employed implicit
Hsu, Po Jen; Lai, S. K.; Rapallo, Arnaldo
2014-03-14
Improved basis sets for the study of polymer dynamics by means of the diffusion theory, and tests on a melt of cis-1,4-polyisoprene decamers, and a toluene solution of a 71-mer syndiotactic trans-1,2-polypentadiene were presented recently [R. Gaspari and A. Rapallo, J. Chem. Phys. 128, 244109 (2008)]. The proposed hybrid basis approach (HBA) combined two techniques, the long time sorting procedure and the maximum correlation approximation. The HBA takes advantage of the strength of these two techniques, and its basis sets proved to be very effective and computationally convenient in describing both local and global dynamics in cases of flexible synthetic polymers where the repeating unit is a unique type of monomer. The question then arises if the same efficacy continues when the HBA is applied to polymers of different monomers, variable local stiffness along the chain and with longer persistence length, which have different local and global dynamical properties against the above-mentioned systems. Important examples of this kind of molecular chains are the proteins, so that a fragment of the protein transthyretin is chosen as the system of the present study. This peptide corresponds to a sequence that is structured in β-sheets of the protein and is located on the surface of the channel with thyroxin. The protein transthyretin forms amyloid fibrils in vivo, whereas the peptide fragment has been shown [C. P. Jaroniec, C. E. MacPhee, N. S. Astrof, C. M. Dobson, and R. G. Griffin, Proc. Natl. Acad. Sci. U.S.A. 99, 16748 (2002)] to form amyloid fibrils in vitro in extended β-sheet conformations. For these reasons the latter is given considerable attention in the literature and studied also as an isolated fragment in water solution where both experimental and theoretical efforts have indicated the propensity of the system to form β turns or α helices, but is otherwise predominantly unstructured. Differing from previous computational studies that employed implicit
Hsu, Po Jen; Lai, S K; Rapallo, Arnaldo
2014-03-14
Improved basis sets for the study of polymer dynamics by means of the diffusion theory, and tests on a melt of cis-1,4-polyisoprene decamers, and a toluene solution of a 71-mer syndiotactic trans-1,2-polypentadiene were presented recently [R. Gaspari and A. Rapallo, J. Chem. Phys. 128, 244109 (2008)]. The proposed hybrid basis approach (HBA) combined two techniques, the long time sorting procedure and the maximum correlation approximation. The HBA takes advantage of the strength of these two techniques, and its basis sets proved to be very effective and computationally convenient in describing both local and global dynamics in cases of flexible synthetic polymers where the repeating unit is a unique type of monomer. The question then arises if the same efficacy continues when the HBA is applied to polymers of different monomers, variable local stiffness along the chain and with longer persistence length, which have different local and global dynamical properties against the above-mentioned systems. Important examples of this kind of molecular chains are the proteins, so that a fragment of the protein transthyretin is chosen as the system of the present study. This peptide corresponds to a sequence that is structured in β-sheets of the protein and is located on the surface of the channel with thyroxin. The protein transthyretin forms amyloid fibrils in vivo, whereas the peptide fragment has been shown [C. P. Jaroniec, C. E. MacPhee, N. S. Astrof, C. M. Dobson, and R. G. Griffin, Proc. Natl. Acad. Sci. U.S.A. 99, 16748 (2002)] to form amyloid fibrils in vitro in extended β-sheet conformations. For these reasons the latter is given considerable attention in the literature and studied also as an isolated fragment in water solution where both experimental and theoretical efforts have indicated the propensity of the system to form β turns or α helices, but is otherwise predominantly unstructured. Differing from previous computational studies that employed implicit
Dharmarajan, Venkatasubramanian; Lee, Jeong-Heon; Patel, Anamika; Skalnik, David G.; Cosgrove, Michael S.
2012-01-01
Translocations and amplifications of the mixed lineage leukemia-1 (MLL1) gene are associated with aggressive myeloid and lymphocytic leukemias in humans. MLL1 is a member of the SET1 family of histone H3 lysine 4 (H3K4) methyltransferases, which are required for transcription of genes involved in hematopoiesis and development. MLL1 associates with a subcomplex containing WDR5, RbBP5, Ash2L, and DPY-30 (WRAD), which together form the MLL1 core complex that is required for sequential mono- and dimethylation of H3K4. We previously demonstrated that WDR5 binds the conserved WDR5 interaction (Win) motif of MLL1 in vitro, an interaction that is required for the H3K4 dimethylation activity of the MLL1 core complex. In this investigation, we demonstrate that arginine 3765 of the MLL1 Win motif is required to co-immunoprecipitate WRAD from mammalian cells, suggesting that the WDR5-Win motif interaction is important for the assembly of the MLL1 core complex in vivo. We also demonstrate that peptides that mimic SET1 family Win motif sequences inhibit H3K4 dimethylation by the MLL1 core complex with varying degrees of efficiency. To understand the structural basis for these differences, we determined structures of WDR5 bound to six different naturally occurring Win motif sequences at resolutions ranging from 1.9 to 1.2 Å. Our results reveal that binding energy differences result from interactions between non-conserved residues C-terminal to the Win motif and to a lesser extent from subtle variation of residues within the Win motif. These results highlight a new class of methylation inhibitors that may be useful for the treatment of MLL1-related malignancies. PMID:22665483
Dharmarajan, Venkatasubramanian; Lee, Jeong-Heon; Patel, Anamika; Skalnik, David G; Cosgrove, Michael S
2012-08-10
Translocations and amplifications of the mixed lineage leukemia-1 (MLL1) gene are associated with aggressive myeloid and lymphocytic leukemias in humans. MLL1 is a member of the SET1 family of histone H3 lysine 4 (H3K4) methyltransferases, which are required for transcription of genes involved in hematopoiesis and development. MLL1 associates with a subcomplex containing WDR5, RbBP5, Ash2L, and DPY-30 (WRAD), which together form the MLL1 core complex that is required for sequential mono- and dimethylation of H3K4. We previously demonstrated that WDR5 binds the conserved WDR5 interaction (Win) motif of MLL1 in vitro, an interaction that is required for the H3K4 dimethylation activity of the MLL1 core complex. In this investigation, we demonstrate that arginine 3765 of the MLL1 Win motif is required to co-immunoprecipitate WRAD from mammalian cells, suggesting that the WDR5-Win motif interaction is important for the assembly of the MLL1 core complex in vivo. We also demonstrate that peptides that mimic SET1 family Win motif sequences inhibit H3K4 dimethylation by the MLL1 core complex with varying degrees of efficiency. To understand the structural basis for these differences, we determined structures of WDR5 bound to six different naturally occurring Win motif sequences at resolutions ranging from 1.9 to 1.2 Å. Our results reveal that binding energy differences result from interactions between non-conserved residues C-terminal to the Win motif and to a lesser extent from subtle variation of residues within the Win motif. These results highlight a new class of methylation inhibitors that may be useful for the treatment of MLL1-related malignancies. PMID:22665483
Holden, Zachary C.; Richard, Ryan M.; Herbert, John M.
2013-12-28
An implementation of Ewald summation for use in mixed quantum mechanics/molecular mechanics (QM/MM) calculations is presented, which builds upon previous work by others that was limited to semi-empirical electronic structure for the QM region. Unlike previous work, our implementation describes the wave function's periodic images using “ChElPG” atomic charges, which are determined by fitting to the QM electrostatic potential evaluated on a real-space grid. This implementation is stable even for large Gaussian basis sets with diffuse exponents, and is thus appropriate when the QM region is described by a correlated wave function. Derivatives of the ChElPG charges with respect to the QM density matrix are a potentially serious bottleneck in this approach, so we introduce a ChElPG algorithm based on atom-centered Lebedev grids. The ChElPG charges thus obtained exhibit good rotational invariance even for sparse grids, enabling significant cost savings. Detailed analysis of the optimal choice of user-selected Ewald parameters, as well as timing breakdowns, is presented.
RANK-ORDER-SELECTIVE NEURONS FORM A TEMPORAL BASIS SET FOR THE GENERATION OF MOTOR SEQUENCES
Salinas, Emilio
2009-01-01
Many behaviors are composed of a series of elementary motor actions that must occur in a specific order, but the neuronal mechanisms by which such motor sequences are generated are poorly understood. In particular, if a sequence consists of a few motor actions, a primate can learn to replicate it from memory after practicing it for just a few trials. How do the motor and premotor areas of the brain assemble motor sequences so fast? The network model presented here reveals part of the solution to this problem. The model is based on experiments showing that, during the performance of motor sequences, some cortical neurons are always activated at specific times, regardless of which motor action is being executed. In the model, a population of such rank-order-selective (ROS) cells drives a layer of downstream motor neurons so that these generate specific movements at different times in different sequences. A key ingredient of the model is that the amplitude of the ROS responses must be modulated by sequence identity. Because of this modulation, which is consistent with experimental reports, the network is able not only to produce multiple sequences accurately but also to learn a new sequence with minimal changes in connectivity. The ROS neurons modulated by sequence identity thus serve as a basis set for constructing arbitrary sequences of motor responses downstream. The underlying mechanism is analogous to the mechanism described in parietal areas for generating coordinate transformations in the spatial domain. PMID:19357265
NASA Astrophysics Data System (ADS)
Park, R.; Jo, D.; Kim, M.; Spracklen, D. V.; Hodzic, A.
2014-12-01
Organic aerosol (OA) constitutes significant mass fractions (20-90%) of total dry fine aerosols in the atmosphere. However, global models of OA have shown large discrepancies when compared to the observations because of the limited capability to simulate secondary OA (SOA). For reducing the discrepancies between observations and models, recent studies have shown that chemical aging reactions in the atmosphere are important because they can lead to decreases in organic volatility, resulting in increase of SOA mass yields. To efficiently simulate chemical aging of SOA in the atmosphere, we implemented the volatility basis set approach in a global 3-D chemical transport model (GEOS-Chem). We present full-year simulations and their comparisons with multiple observations - global aerosol mass spectrometer dataset, the Interagency Monitoring of Protected Visual Environments from the United States, the European Monitoring and Evaluation Programme dataset and water-soluble organic carbon observation data collected over East Asia. Using different input parameters in the model, we also explore the uncertainty of the SOA simulation for which we use an observational constraint to find the optimized values with which the model reduces the discrepancy from the observations. Finally, we estimate the effect of OA on climate using our best simulation results.
The Scientific Basis of Uncertainty Factors Used in Setting Occupational Exposure Limits.
Dankovic, D A; Naumann, B D; Maier, A; Dourson, M L; Levy, L S
2015-01-01
The uncertainty factor concept is integrated into health risk assessments for all aspects of public health practice, including by most organizations that derive occupational exposure limits. The use of uncertainty factors is predicated on the assumption that a sufficient reduction in exposure from those at the boundary for the onset of adverse effects will yield a safe exposure level for at least the great majority of the exposed population, including vulnerable subgroups. There are differences in the application of the uncertainty factor approach among groups that conduct occupational assessments; however, there are common areas of uncertainty which are considered by all or nearly all occupational exposure limit-setting organizations. Five key uncertainties that are often examined include interspecies variability in response when extrapolating from animal studies to humans, response variability in humans, uncertainty in estimating a no-effect level from a dose where effects were observed, extrapolation from shorter duration studies to a full life-time exposure, and other insufficiencies in the overall health effects database indicating that the most sensitive adverse effect may not have been evaluated. In addition, a modifying factor is used by some organizations to account for other remaining uncertainties-typically related to exposure scenarios or accounting for the interplay among the five areas noted above. Consideration of uncertainties in occupational exposure limit derivation is a systematic process whereby the factors applied are not arbitrary, although they are mathematically imprecise. As the scientific basis for uncertainty factor application has improved, default uncertainty factors are now used only in the absence of chemical-specific data, and the trend is to replace them with chemical-specific adjustment factors whenever possible. The increased application of scientific data in the development of uncertainty factors for individual chemicals also has
The Scientific Basis of Uncertainty Factors Used in Setting Occupational Exposure Limits
Dankovic, D. A.; Naumann, B. D.; Maier, A.; Dourson, M. L.; Levy, L. S.
2015-01-01
The uncertainty factor concept is integrated into health risk assessments for all aspects of public health practice, including by most organizations that derive occupational exposure limits. The use of uncertainty factors is predicated on the assumption that a sufficient reduction in exposure from those at the boundary for the onset of adverse effects will yield a safe exposure level for at least the great majority of the exposed population, including vulnerable subgroups. There are differences in the application of the uncertainty factor approach among groups that conduct occupational assessments; however, there are common areas of uncertainty which are considered by all or nearly all occupational exposure limit-setting organizations. Five key uncertainties that are often examined include interspecies variability in response when extrapolating from animal studies to humans, response variability in humans, uncertainty in estimating a no-effect level from a dose where effects were observed, extrapolation from shorter duration studies to a full life-time exposure, and other insufficiencies in the overall health effects database indicating that the most sensitive adverse effect may not have been evaluated. In addition, a modifying factor is used by some organizations to account for other remaining uncertainties—typically related to exposure scenarios or accounting for the interplay among the five areas noted above. Consideration of uncertainties in occupational exposure limit derivation is a systematic process whereby the factors applied are not arbitrary, although they are mathematically imprecise. As the scientific basis for uncertainty factor application has improved, default uncertainty factors are now used only in the absence of chemical-specific data, and the trend is to replace them with chemical-specific adjustment factors whenever possible. The increased application of scientific data in the development of uncertainty factors for individual chemicals also
The Scientific Basis of Uncertainty Factors Used in Setting Occupational Exposure Limits.
Dankovic, D A; Naumann, B D; Maier, A; Dourson, M L; Levy, L S
2015-01-01
The uncertainty factor concept is integrated into health risk assessments for all aspects of public health practice, including by most organizations that derive occupational exposure limits. The use of uncertainty factors is predicated on the assumption that a sufficient reduction in exposure from those at the boundary for the onset of adverse effects will yield a safe exposure level for at least the great majority of the exposed population, including vulnerable subgroups. There are differences in the application of the uncertainty factor approach among groups that conduct occupational assessments; however, there are common areas of uncertainty which are considered by all or nearly all occupational exposure limit-setting organizations. Five key uncertainties that are often examined include interspecies variability in response when extrapolating from animal studies to humans, response variability in humans, uncertainty in estimating a no-effect level from a dose where effects were observed, extrapolation from shorter duration studies to a full life-time exposure, and other insufficiencies in the overall health effects database indicating that the most sensitive adverse effect may not have been evaluated. In addition, a modifying factor is used by some organizations to account for other remaining uncertainties-typically related to exposure scenarios or accounting for the interplay among the five areas noted above. Consideration of uncertainties in occupational exposure limit derivation is a systematic process whereby the factors applied are not arbitrary, although they are mathematically imprecise. As the scientific basis for uncertainty factor application has improved, default uncertainty factors are now used only in the absence of chemical-specific data, and the trend is to replace them with chemical-specific adjustment factors whenever possible. The increased application of scientific data in the development of uncertainty factors for individual chemicals also has
The study of basis sets for the calculation of the structure and dynamics of the benzene-Kr complex
Shirkov, Leonid; Makarewicz, Jan
2015-05-28
An ab initio intermolecular potential energy surface (PES) has been constructed for the benzene-krypton (BKr) van der Waals (vdW) complex. The interaction energy has been calculated at the coupled cluster level of theory with single, double, and perturbatively included triple excitations using different basis sets. As a result, a few analytical PESs of the complex have been determined. They allowed a prediction of the complex structure and its vibrational vdW states. The vibrational energy level pattern exhibits a distinct polyad structure. Comparison of the equilibrium structure, the dipole moment, and vibrational levels of BKr with their experimental counterparts has allowed us to design an optimal basis set composed of a small Dunning’s basis set for the benzene monomer, a larger effective core potential adapted basis set for Kr and additional midbond functions. Such a basis set yields vibrational energy levels that agree very well with the experimental ones as well as with those calculated from the available empirical PES derived from the microwave spectra of the BKr complex. The basis proposed can be applied to larger complexes including Kr because of a reasonable computational cost and accurate results.
The study of basis sets for the calculation of the structure and dynamics of the benzene-Kr complex.
Shirkov, Leonid; Makarewicz, Jan
2015-05-28
An ab initio intermolecular potential energy surface (PES) has been constructed for the benzene-krypton (BKr) van der Waals (vdW) complex. The interaction energy has been calculated at the coupled cluster level of theory with single, double, and perturbatively included triple excitations using different basis sets. As a result, a few analytical PESs of the complex have been determined. They allowed a prediction of the complex structure and its vibrational vdW states. The vibrational energy level pattern exhibits a distinct polyad structure. Comparison of the equilibrium structure, the dipole moment, and vibrational levels of BKr with their experimental counterparts has allowed us to design an optimal basis set composed of a small Dunning's basis set for the benzene monomer, a larger effective core potential adapted basis set for Kr and additional midbond functions. Such a basis set yields vibrational energy levels that agree very well with the experimental ones as well as with those calculated from the available empirical PES derived from the microwave spectra of the BKr complex. The basis proposed can be applied to larger complexes including Kr because of a reasonable computational cost and accurate results.
The study of basis sets for the calculation of the structure and dynamics of the benzene-Kr complex.
Shirkov, Leonid; Makarewicz, Jan
2015-05-28
An ab initio intermolecular potential energy surface (PES) has been constructed for the benzene-krypton (BKr) van der Waals (vdW) complex. The interaction energy has been calculated at the coupled cluster level of theory with single, double, and perturbatively included triple excitations using different basis sets. As a result, a few analytical PESs of the complex have been determined. They allowed a prediction of the complex structure and its vibrational vdW states. The vibrational energy level pattern exhibits a distinct polyad structure. Comparison of the equilibrium structure, the dipole moment, and vibrational levels of BKr with their experimental counterparts has allowed us to design an optimal basis set composed of a small Dunning's basis set for the benzene monomer, a larger effective core potential adapted basis set for Kr and additional midbond functions. Such a basis set yields vibrational energy levels that agree very well with the experimental ones as well as with those calculated from the available empirical PES derived from the microwave spectra of the BKr complex. The basis proposed can be applied to larger complexes including Kr because of a reasonable computational cost and accurate results. PMID:26026434
Fast Electron Correlation Methods for Molecular Clusters without Basis Set Superposition Errors
Kamiya, Muneaki; Hirata, So; Valiev, Marat
2008-02-19
Two critical extensions to our fast, accurate, and easy-to-implement binary or ternary interaction method for weakly-interacting molecular clusters [Hirata et al. Mol. Phys. 103, 2255 (2005)] have been proposed, implemented, and applied to water hexamers, hydrogen fluoride chains and rings, and neutral and zwitterionic glycine–water clusters with an excellent result for an initial performance assessment. Our original method included up to two- or three-body Coulomb, exchange, and correlation energies exactly and higher-order Coulomb energies in the dipole–dipole approximation. In this work, the dipole moments are replaced by atom-centered point charges determined so that they reproduce the electrostatic potentials of the cluster subunits as closely as possible and also self-consistently with one another in the cluster environment. They have been shown to lead to dramatic improvement in the description of short-range electrostatic potentials not only of large, charge-separated subunits like zwitterionic glycine but also of small subunits. Furthermore, basis set superposition errors (BSSE) known to plague direct evaluation of weak interactions have been eliminated by com-bining the Valiron–Mayer function counterpoise (VMFC) correction with our binary or ternary interaction method in an economical fashion (quadratic scaling n2 with respect to the number of subunits n when n is small and linear scaling when n is large). A new variant of VMFC has also been proposed in which three-body and all higher-order Coulomb effects on BSSE are estimated approximately. The BSSE-corrected ternary interaction method with atom-centered point charges reproduces the VMFC-corrected results of conventional electron correlation calculations within 0.1 kcal/mol. The proposed method is significantly more accurate and also efficient than conventional correlation methods uncorrected of BSSE.
Basis set dependence using DFT/B3LYP calculations to model the Raman spectrum of thymine.
Bielecki, Jakub; Lipiec, Ewelina
2016-02-01
Raman spectroscopy (including surface enhanced Raman spectroscopy (SERS) and tip enhanced Raman spectroscopy (TERS)) is a highly promising experimental method for investigations of biomolecule damage induced by ionizing radiation. However, proper interpretation of changes in experimental spectra for complex systems is often difficult or impossible, thus Raman spectra calculations based on density functional theory (DFT) provide an invaluable tool as an additional layer of understanding of underlying processes. There are many works that address the problem of basis set dependence for energy and bond length consideration, nevertheless there is still lack of consistent research on basis set influence on Raman spectra intensities for biomolecules. This study fills this gap by investigating of the influence of basis set choice for the interpretation of Raman spectra of the thymine molecule calculated using the DFT/B3LYP framework and comparing these results with experimental spectra. Among 19 selected Pople's basis sets, the best agreement was achieved using 6-31[Formula: see text](d,p), 6-31[Formula: see text](d,p) and 6-11[Formula: see text]G(d,p) sets. Adding diffuse functions or polarized functions for small basis set or use of a medium or large basis set without diffuse or polarized functions is not sufficient to reproduce Raman intensities correctly. The introduction of the diffuse functions ([Formula: see text]) on hydrogen atoms is not necessary for gas phase calculations. This work serves as a benchmark for further research on the interaction of ionizing radiation with DNA molecules by means of ab initio calculations and Raman spectroscopy. Moreover, this work provides a set of new scaling factors for Raman spectra calculation in the framework of DFT/B3LYP method.
NASA Astrophysics Data System (ADS)
Kobus, J.; Moncrieff, D.; Wilson, S.
2004-02-01
In a previous paper, we have made a comparison of the accuracy with which the electric dipole polarizability agrzz and hyperpolarizability bgrzzz can be calculated by using either the finite basis set approach (the algebraic approximation) or the finite difference method in calculations for the ground states of the H2, LiH, BH and FH molecules, at their respective experimental equilibrium geometries, within the Hartree-Fock model. A re-examination of the hyperpolarizability of the BH molecule shows it to be very sensitive both to the choice of grid employed in the finite difference Hartree-Fock calculation and the construction of the basis set used in the matrix Hartree-Fock study. A new comparison of finite difference and finite basis set hyperpolarizabilities for the BH molecule is made, together with new calculations for the LiH and FH ground states.
NASA Astrophysics Data System (ADS)
Suleimanov, Yu V.; Tscherbul, Timur V.
2016-10-01
We explore the combined effect of the uncertainties due to the interaction potential and basis set convergence on low-temperature collisional properties of spin-polarized NH molecules in a magnetic field. We show that quantum scattering calculations with different rotational basis sets and λ-scaled interaction potentials produce qualitatively different ratios of elastic to inelastic cross sections for collision energies above 10‑3 cm‑1, leading to favorable (unfavorable) prospects for sympathetic cooling of NH molecules depending on the basis set cutoff parameter {N}{{\\max }}. The physical reason behind this effect is that the resonance widths, which determine the maximum variation of the scattering cross sections with λ, tend to depend strongly on {N}{{\\max }}. At ultralow collision energies, all basis sets produce highly uncertain (and statistically indistinguishable) elastic and inelastic cross sections; however, their ratio γ is much less sensitive to small variations of the interaction potential. Our results highlight the importance of basis set convergence in quantum scattering calculations and establish the existence of parameter regimes where unconverged calculations can still be used to make qualitatively accurate predictions of scattering observables.
Hill, J Grant
2013-09-30
Auxiliary basis sets (ABS) specifically matched to the cc-pwCVnZ-PP and aug-cc-pwCVnZ-PP orbital basis sets (OBS) have been developed and optimized for the 4d elements Y-Pd at the second-order Møller-Plesset perturbation theory level. Calculation of the core-valence electron correlation energies for small to medium sized transition metal complexes demonstrates that the error due to the use of these new sets in density fitting is three to four orders of magnitude smaller than that due to the OBS incompleteness, and hence is considered negligible. Utilizing the ABSs in the resolution-of-the-identity component of explicitly correlated calculations is also investigated, where it is shown that i-type functions are important to produce well-controlled errors in both integrals and correlation energy. Benchmarking at the explicitly correlated coupled cluster with single, double, and perturbative triple excitations level indicates impressive convergence with respect to basis set size for the spectroscopic constants of 4d monofluorides; explicitly correlated double-ζ calculations produce results close to conventional quadruple-ζ, and triple-ζ is within chemical accuracy of the complete basis set limit.
Evaluation of European air quality modelled by CAMx including the volatility basis set scheme
NASA Astrophysics Data System (ADS)
Ciarelli, Giancarlo; Aksoyoglu, Sebnem; Crippa, Monica; Jimenez, Jose-Luis; Nemitz, Eriko; Sellegri, Karine; Äijälä, Mikko; Carbone, Samara; Mohr, Claudia; O'Dowd, Colin; Poulain, Laurent; Baltensperger, Urs; Prévôt, André S. H.
2016-08-01
Four periods of EMEP (European Monitoring and Evaluation Programme) intensive measurement campaigns (June 2006, January 2007, September-October 2008 and February-March 2009) were modelled using the regional air quality model CAMx with VBS (volatility basis set) approach for the first time in Europe within the framework of the EURODELTA-III model intercomparison exercise. More detailed analysis and sensitivity tests were performed for the period of February-March 2009 and June 2006 to investigate the uncertainties in emissions as well as to improve the modelling of organic aerosol (OA). Model performance for selected gas phase species and PM2.5 was evaluated using the European air quality database AirBase. Sulfur dioxide (SO2) and ozone (O3) were found to be overestimated for all the four periods, with O3 having the largest mean bias during June 2006 and January-February 2007 periods (8.9 pbb and 12.3 ppb mean biases respectively). In contrast, nitrogen dioxide (NO2) and carbon monoxide (CO) were found to be underestimated for all the four periods. CAMx reproduced both total concentrations and monthly variations of PM2.5 for all the four periods with average biases ranging from -2.1 to 1.0 µg m-3. Comparisons with AMS (aerosol mass spectrometer) measurements at different sites in Europe during February-March 2009 showed that in general the model overpredicts the inorganic aerosol fraction and underpredicts the organic one, such that the good agreement for PM2.5 is partly due to compensation of errors. The effect of the choice of VBS scheme on OA was investigated as well. Two sensitivity tests with volatility distributions based on previous chamber and ambient measurements data were performed. For February-March 2009 the chamber case reduced the total OA concentrations by about 42 % on average. In contrast, a test based on ambient measurement data increased OA concentrations by about 42 % for the same period bringing model and observations into better agreement
NASA Astrophysics Data System (ADS)
Turovtsev, V. V.; Orlov, Yu. D.; Tsirulev, A. N.
2015-08-01
The advantages of the orthonormal basis set of 2π-periodic Mathieu functions compared to the trigonometric basis set in calculations of torsional states of molecules are substantiated. Explicit expressions are derived for calculating the Hamiltonian matrix elements of a one-dimensional torsional Schrödinger equation with a periodic potential of the general form in the basis set of Mathieu functions. It is shown that variation of a parameter of Mathieu functions allows the rotation potential and the structural function to be approximated with a good accuracy by a small number of series terms. The conditions for the best choice of this parameter are specified, and approximations are obtained for torsional potentials of n-butane upon rotation about the central C-C bond and of its univalent radical n-butyl C2H5C·H2 upon rotation of the C·H2 group. All algorithms are implemented in the Maple package.
Reuter, Matthew G; Harrison, Robert J
2013-09-21
We revisit the derivation of electron transport theories with a focus on the projection operators chosen to partition the system. The prevailing choice of assigning each computational basis function to a region causes two problems. First, this choice generally results in oblique projection operators, which are non-Hermitian and violate implicit assumptions in the derivation. Second, these operators are defined with the physically insignificant basis set and, as such, preclude a well-defined basis set limit. We thus advocate for the selection of physically motivated, orthogonal projection operators (which are Hermitian) and present an operator-based derivation of electron transport theories. Unlike the conventional, matrix-based approaches, this derivation requires no knowledge of the computational basis set. In this process, we also find that common transport formalisms for nonorthogonal basis sets improperly decouple the exterior regions, leading to a short circuit through the system. We finally discuss the implications of these results for first-principles calculations of electron transport.
Brorsen, Kurt R.; Sirjoosingh, Andrew; Pak, Michael V.; Hammes-Schiffer, Sharon
2015-06-07
The nuclear electronic orbital (NEO) reduced explicitly correlated Hartree-Fock (RXCHF) approach couples select electronic orbitals to the nuclear orbital via Gaussian-type geminal functions. This approach is extended to enable the use of a restricted basis set for the explicitly correlated electronic orbitals and an open-shell treatment for the other electronic orbitals. The working equations are derived and the implementation is discussed for both extensions. The RXCHF method with a restricted basis set is applied to HCN and FHF{sup −} and is shown to agree quantitatively with results from RXCHF calculations with a full basis set. The number of many-particle integrals that must be calculated for these two molecules is reduced by over an order of magnitude with essentially no loss in accuracy, and the reduction factor will increase substantially for larger systems. Typically, the computational cost of RXCHF calculations with restricted basis sets will scale in terms of the number of basis functions centered on the quantum nucleus and the covalently bonded neighbor(s). In addition, the RXCHF method with an odd number of electrons that are not explicitly correlated to the nuclear orbital is implemented using a restricted open-shell formalism for these electrons. This method is applied to HCN{sup +}, and the nuclear densities are in qualitative agreement with grid-based calculations. Future work will focus on the significance of nonadiabatic effects in molecular systems and the further enhancement of the NEO-RXCHF approach to accurately describe such effects.
NASA Astrophysics Data System (ADS)
Haiduke, Roberto L. A.; Comar, Moacyr; da Silva, Albérico B. F.
2006-12-01
The prolapse-free relativistic adapted Gaussian basis sets (RAGBSs), developed by our research group on the basis of the four-component approach, are used for the first time in Douglas-Kroll-Hess 2nd order scalar relativistic calculations (DKH2) of simple diatomic molecules containing Hydrogen and the halogens from Fluorine up to Iodine: HX and X 2, where X = F, Cl, Br, and I. To this end, the RAGBSs were contracted with the general contraction scheme to triple-, quadruple-, and quintuple-zeta sets. Polarization functions were also added to the basis sets by optimization with the configuration interaction method including single and double excitations into the DKH2 environment, DKH2-CISD. The molecular properties were then calculated with the coupled cluster electronic correlation treatment and the DKH2 scalar relativistic method, DKH2-CCSD(T), and indicated that our RAGBSs should be contracted as quadruple-zeta basis sets. The results achieved with the DKH2-CCSD(T) calculations and the selected quadruple-zeta RAGBSs are able to reproduce the experimental data of equilibrium distances, dissociation energies, and harmonic vibrational frequencies with root-mean-square (rms) errors of 0.015 Å, 3.6 kcal mol -1, and 21.7 cm -1, respectively.
Celeste, Ricardo; Maringolo, Milena P; Comar, Moacyr; Viana, Rommel B; Guimarães, Amanda R; Haiduke, Roberto L A; da Silva, Albérico B F
2015-10-01
Accurate Gaussian basis sets for atoms from H to Ba were obtained by means of the generator coordinate Hartree-Fock (GCHF) method based on a polynomial expansion to discretize the Griffin-Wheeler-Hartree-Fock equations (GWHF). The discretization of the GWHF equations in this procedure is based on a mesh of points not equally distributed in contrast with the original GCHF method. The results of atomic Hartree-Fock energies demonstrate the capability of these polynomial expansions in designing compact and accurate basis sets to be used in molecular calculations and the maximum error found when compared to numerical values is only 0.788 mHartree for indium. Some test calculations with the B3LYP exchange-correlation functional for N2, F2, CO, NO, HF, and HCN show that total energies within 1.0 to 2.4 mHartree compared to the cc-pV5Z basis sets are attained with our contracted bases with a much smaller number of polarization functions (2p1d and 2d1f for hydrogen and heavier atoms, respectively). Other molecular calculations performed here are also in very good accordance with experimental and cc-pV5Z results. The most important point to be mentioned here is that our generator coordinate basis sets required only a tiny fraction of the computational time when compared to B3LYP/cc-pV5Z calculations.
Basis set dependence of ab initio SCF elastic, Born, electron scattering cross sections for C2H4
NASA Astrophysics Data System (ADS)
Xie, Shang-de; Fink, M.; Kohl, D. A.
1984-08-01
The results of ab initio Hartree-Fock calculations of the orientationally averaged, elastic electron scattering cross section of C2H4 with six different basis sets are reported. The averaging and Fourier transform were calculated by the approach of Kohl, Pulay, and Fink. Six different basis sets, ranging from 6-31G to 6-311 G4*, were employed in the calculations. The improvement in the calculated Born cross section parallelled the lowering of the energy as the basis was varied. For C2H4, a calculation at the 6-311G** level provides a good description of the cross section at a modest expenditure of computational time.
Holocene sea level variations on the basis of integration of independent data sets
Sahagian, D.; Berkman, P. . Dept. of Geological Sciences and Byrd Polar Research Center)
1992-01-01
Variations in sea level through earth history have occurred at a wide variety of time scales. Sea level researchers have attacked the problem of measuring these sea level changes through a variety of approaches, each relevant only to the time scale in question, and usually only relevant to the specific locality from which a specific type of data are derived. There is a plethora of different data types that can and have been used (locally) for the measurement of Holocene sea level variations. The problem of merging different data sets for the purpose of constructing a global eustatic sea level curve for the Holocene has not previously been adequately addressed. The authors direct the efforts to that end. Numerous studies have been published regarding Holocene sea level changes. These have involved exposed fossil reef elevations, elevation of tidal deltas, elevation of depth of intertidal peat deposits, caves, tree rings, ice cores, moraines, eolian dune ridges, marine-cut terrace elevations, marine carbonate species, tide gauges, and lake level variations. Each of these data sets is based on particular set of assumptions, and is valid for a specific set of environments. In order to obtain the most accurate possible sea level curve for the Holocene, these data sets must be merged so that local and other influences can be filtered out of each data set. Since each data set involves very different measurements, each is scaled in order to define the sensitivity of the proxy measurement parameter to sea level, including error bounds. This effectively determines the temporal and spatial resolution of each data set. The level of independence of data sets is also quantified, in order to rule out the possibility of a common non-eustatic factor affecting more than one variety of data. The Holocene sea level curve is considered to be independent of other factors affecting the proxy data, and is taken to represent the relation between global ocean water and basin volumes.
NASA Astrophysics Data System (ADS)
Witte, Jonathon; Neaton, Jeffrey B.; Head-Gordon, Martin
2016-05-01
With the aim of systematically characterizing the convergence of common families of basis sets such that general recommendations for basis sets can be made, we have tested a wide variety of basis sets against complete-basis binding energies across the S22 set of intermolecular interactions—noncovalent interactions of small and medium-sized molecules consisting of first- and second-row atoms—with three distinct density functional approximations: SPW92, a form of local-density approximation; B3LYP, a global hybrid generalized gradient approximation; and B97M-V, a meta-generalized gradient approximation with nonlocal correlation. We have found that it is remarkably difficult to reach the basis set limit; for the methods and systems examined, the most complete basis is Jensen's pc-4. The Dunning correlation-consistent sequence of basis sets converges slowly relative to the Jensen sequence. The Karlsruhe basis sets are quite cost effective, particularly when a correction for basis set superposition error is applied: counterpoise-corrected def2-SVPD binding energies are better than corresponding energies computed in comparably sized Dunning and Jensen bases, and on par with uncorrected results in basis sets 3-4 times larger. These trends are exhibited regardless of the level of density functional approximation employed. A sense of the magnitude of the intrinsic incompleteness error of each basis set not only provides a foundation for guiding basis set choice in future studies but also facilitates quantitative comparison of existing studies on similar types of systems.
Witte, Jonathon; Neaton, Jeffrey B; Head-Gordon, Martin
2016-05-21
With the aim of systematically characterizing the convergence of common families of basis sets such that general recommendations for basis sets can be made, we have tested a wide variety of basis sets against complete-basis binding energies across the S22 set of intermolecular interactions-noncovalent interactions of small and medium-sized molecules consisting of first- and second-row atoms-with three distinct density functional approximations: SPW92, a form of local-density approximation; B3LYP, a global hybrid generalized gradient approximation; and B97M-V, a meta-generalized gradient approximation with nonlocal correlation. We have found that it is remarkably difficult to reach the basis set limit; for the methods and systems examined, the most complete basis is Jensen's pc-4. The Dunning correlation-consistent sequence of basis sets converges slowly relative to the Jensen sequence. The Karlsruhe basis sets are quite cost effective, particularly when a correction for basis set superposition error is applied: counterpoise-corrected def2-SVPD binding energies are better than corresponding energies computed in comparably sized Dunning and Jensen bases, and on par with uncorrected results in basis sets 3-4 times larger. These trends are exhibited regardless of the level of density functional approximation employed. A sense of the magnitude of the intrinsic incompleteness error of each basis set not only provides a foundation for guiding basis set choice in future studies but also facilitates quantitative comparison of existing studies on similar types of systems.
Brandenburg, Jan Gerit; Alessio, Maristella; Civalleri, Bartolomeo; Peintinger, Michael F; Bredow, Thomas; Grimme, Stefan
2013-09-26
We extend the previously developed geometrical correction for the inter- and intramolecular basis set superposition error (gCP) to periodic density functional theory (DFT) calculations. We report gCP results compared to those from the standard Boys-Bernardi counterpoise correction scheme and large basis set calculations. The applicability of the method to molecular crystals as the main target is tested for the benchmark set X23. It consists of 23 noncovalently bound crystals as introduced by Johnson et al. (J. Chem. Phys. 2012, 137, 054103) and refined by Tkatchenko et al. (J. Chem. Phys. 2013, 139, 024705). In order to accurately describe long-range electron correlation effects, we use the standard atom-pairwise dispersion correction scheme DFT-D3. We show that a combination of DFT energies with small atom-centered basis sets, the D3 dispersion correction, and the gCP correction can accurately describe van der Waals and hydrogen-bonded crystals. Mean absolute deviations of the X23 sublimation energies can be reduced by more than 70% and 80% for the standard functionals PBE and B3LYP, respectively, to small residual mean absolute deviations of about 2 kcal/mol (corresponding to 13% of the average sublimation energy). As a further test, we compute the interlayer interaction of graphite for varying distances and obtain a good equilibrium distance and interaction energy of 6.75 Å and -43.0 meV/atom at the PBE-D3-gCP/SVP level. We fit the gCP scheme for a recently developed pob-TZVP solid-state basis set and obtain reasonable results for the X23 benchmark set and the potential energy curve for water adsorption on a nickel (110) surface.
NASA Astrophysics Data System (ADS)
Ma, Zhonghua; Zhang, Yanli; Tuckerman, Mark E.
2012-07-01
It is generally believed that studies of liquid water using the generalized gradient approximation to density functional theory require dispersion corrections in order to obtain reasonably accurate structural and dynamical properties. Here, we report on an ab initio molecular dynamics study of water in the isothermal-isobaric ensemble using a converged discrete variable representation basis set and an empirical dispersion correction due to Grimme [J. Comp. Chem. 27, 1787 (2006)], 10.1002/jcc.20495. At 300 K and an applied pressure of 1 bar, the density obtained without dispersion corrections is approximately 0.92 g/cm3 while that obtained with dispersion corrections is 1.07 g/cm3, indicating that the empirical dispersion correction overestimates the density by almost as much as it is underestimated without the correction for this converged basis. Radial distribution functions exhibit a loss of structure in the second solvation shell. Comparison of our results with other studies using the same empirical correction suggests the cause of the discrepancy: the Grimme dispersion correction is parameterized for use with a particular basis set; this parameterization is sensitive to this choice and, therefore, is not transferable to other basis sets.
Accelerating wavefunction in density-functional-theory embedding by truncating the active basis set.
Bennie, Simon J; Stella, Martina; Miller, Thomas F; Manby, Frederick R
2015-07-14
Methods where an accurate wavefunction is embedded in a density-functional description of the surrounding environment have recently been simplified through the use of a projection operator to ensure orthogonality of orbital subspaces. Projector embedding already offers significant performance gains over conventional post-Hartree-Fock methods by reducing the number of correlated occupied orbitals. However, in our first applications of the method, we used the atomic-orbital basis for the full system, even for the correlated wavefunction calculation in a small, active subsystem. Here, we further develop our method for truncating the atomic-orbital basis to include only functions within or close to the active subsystem. The number of atomic orbitals in a calculation on a fixed active subsystem becomes asymptotically independent of the size of the environment, producing the required O(N(0)) scaling of cost of the calculation in the active subsystem, and accuracy is controlled by a single parameter. The applicability of this approach is demonstrated for the embedded many-body expansion of binding energies of water hexamers and calculation of reaction barriers of SN2 substitution of fluorine by chlorine in α-fluoroalkanes.
NASA Astrophysics Data System (ADS)
Heaps, Charles W.; Mazziotti, David A.
2016-08-01
Quantum molecular dynamics requires an accurate representation of the molecular potential energy surface from a minimal number of electronic structure calculations, particularly for nonadiabatic dynamics where excited states are required. In this paper, we employ pseudospectral sampling of time-dependent Gaussian basis functions for the simulation of non-adiabatic dynamics. Unlike other methods, the pseudospectral Gaussian molecular dynamics tests the Schrödinger equation with N Dirac delta functions located at the centers of the Gaussian functions reducing the scaling of potential energy evaluations from O ( N 2 ) to O ( N ) . By projecting the Gaussian basis onto discrete points in space, the method is capable of efficiently and quantitatively describing the nonadiabatic population transfer and intra-surface quantum coherence. We investigate three model systems: the photodissociation of three coupled Morse oscillators, the bound state dynamics of two coupled Morse oscillators, and a two-dimensional model for collinear triatomic vibrational dynamics. In all cases, the pseudospectral Gaussian method is in quantitative agreement with numerically exact calculations. The results are promising for nonadiabatic molecular dynamics in molecular systems where strongly correlated ground or excited states require expensive electronic structure calculations.
Zhang, Jun Dolg, Michael
2014-01-28
The third-order incremental dual-basis set zero-buffer approach was combined with CCSD(T)-F12x (x = a, b) theory to develop a new approach, i.e., the inc3-db-B0-CCSD(T)-F12 method, which can be applied as a black-box procedure to efficiently obtain the near complete basis set (CBS) limit of the CCSD(T) energies also for large systems. We tested this method for several cases of different chemical nature: four complexes taken from the standard benchmark sets S66 and X40, the energy difference between isomers of water hexamer and the rotation barrier of biphenyl. The results show that our method has an error relative to the best estimation of CBS energy of only 0.2 kcal/mol or less. By parallelization, our method can accomplish the CCSD(T)-F12 calculations of about 60 correlated electrons and 800 basis functions in only several days, which by standard implementation are impossible for ordinary hardware. We conclude that the inc3-db-B0-CCSD(T)-F12a/AVTZ method, which is of CCSD(T)/AV5Z quality, is close to the limit of accuracy that one can achieve for large systems currently.
On the Kohn-Sham density response in a localized basis set
NASA Astrophysics Data System (ADS)
Foerster, Dietrich; Koval, Peter
2009-07-01
We construct the Kohn-Sham density response function χ0 in a previously described basis of the space of orbital products. The calculational complexity of our construction is O(N2Nω) for a molecule of N atoms and in a spectroscopic window of Nω frequency points. As a first application, we use χ0 to calculate the molecular spectra from the Petersilka-Gossmann-Gross equation. With χ0 as input, we obtain the correct spectra with an extra computational effort that grows also as O(N2Nω) and, therefore, less steeply in N than the O(N3) complexity of solving Casida's equations. Our construction should be useful for the study of excitons in molecular physics and in related areas where χ0 is a crucial ingredient.
NASA Astrophysics Data System (ADS)
Purwanto, Wirawan; Krakauer, Henry; Zhang, Shiwei; Virgus, Yudistira
2011-03-01
Weak H2 physisorption energies present a significant challenge to first-principle theoretical modeling and prediction of materials for H storage. There has been controversy regarding the accuracy of DFT on systems involving Ca cations. We use the auxiliary-field quantum Monte Carlo (AFQMC) method to accurately predict the binding energy of Ca + , - 4{H}2 . AFQMC scales as Nbasis3and has demonstrated accuracy similar to or better than the gold-standard coupled cluster CCSD(T) method. We apply a modified Cholesky decomposition to achieve efficient Hubbard-Stratonovich transformation in AFQMC at large basis sizes. We employ the largest correlation consistent basis sets available, up to Ca/cc-pCV5Z, to extrapolate to the complete basis limit. The calculated potential energy curve exhibits binding with a double-well structure. Supported by DOE and NSF. Calculations were performed at OLCF Jaguar and CPD.
Liquid Water through Density-Functional Molecular Dynamics: Plane-Wave vs Atomic-Orbital Basis Sets.
Miceli, Giacomo; Hutter, Jürg; Pasquarello, Alfredo
2016-08-01
We determine and compare structural, dynamical, and electronic properties of liquid water at near ambient conditions through density-functional molecular dynamics simulations, when using either plane-wave or atomic-orbital basis sets. In both frameworks, the electronic structure and the atomic forces are self-consistently determined within the same theoretical scheme based on a nonlocal density functional accounting for van der Waals interactions. The overall properties of liquid water achieved within the two frameworks are in excellent agreement with each other. Thus, our study supports that implementations with plane-wave or atomic-orbital basis sets yield equivalent results and can be used indiscriminately in study of liquid water or aqueous solutions.
Liquid Water through Density-Functional Molecular Dynamics: Plane-Wave vs Atomic-Orbital Basis Sets.
Miceli, Giacomo; Hutter, Jürg; Pasquarello, Alfredo
2016-08-01
We determine and compare structural, dynamical, and electronic properties of liquid water at near ambient conditions through density-functional molecular dynamics simulations, when using either plane-wave or atomic-orbital basis sets. In both frameworks, the electronic structure and the atomic forces are self-consistently determined within the same theoretical scheme based on a nonlocal density functional accounting for van der Waals interactions. The overall properties of liquid water achieved within the two frameworks are in excellent agreement with each other. Thus, our study supports that implementations with plane-wave or atomic-orbital basis sets yield equivalent results and can be used indiscriminately in study of liquid water or aqueous solutions. PMID:27434607
Macedo, Luiz Guilherme M de Borin, Antonio Carlos; Silva, Alberico B.F. da
2007-11-15
Prolapse-free basis sets suitable for four-component relativistic quantum chemical calculations are presented for the superheavy elements up to {sub 118}Uuo ({sub 104}Rf, {sub 105}Db, {sub 106}Sg, {sub 107}Bh, {sub 108}Hs, {sub 109}Mt, {sub 110}Ds, {sub 111}Rg, {sub 112}Uub, {sub 113}Uut, {sub 114}Uuq, {sub 115}Uup, {sub 116}Uuh, {sub 117}Uus, {sub 118}Uuo) and {sub 103}Lr. These basis sets were optimized by minimizing the absolute values of the energy difference between the Dirac-Fock-Roothaan total energy and the corresponding numerical value at a milli-Hartree order of magnitude, resulting in a good balance between cost and accuracy. Parameters for generating exponents and new numerical data for some superheavy elements are also presented.
NASA Technical Reports Server (NTRS)
Almloef, Jan; Taylor, Peter R.
1989-01-01
A recently proposed scheme for using natural orbitals from atomic configuration interaction (CI) wave functions as a basis set for linear combination of atomic orbitals (LCAO) calculations is extended for the calculation of molecular properties. For one-electron properties like multipole moments, which are determined largely by the outermost regions of the molecular wave function, it is necessary to increase the flexibility of the basis in these regions. This is most easily done by uncontracting the outmost Gaussian primitives, and/or by adding diffuse primitives. A similar approach can be employed for the calculation of polarizabilities. Properties which are not dominated by the long-range part of the wave function, such as spectroscopic constants or electric field gradients at the nucleus, can generally be treated satisfactorily with the original atomic natural orbital (ANO) sets.
NASA Astrophysics Data System (ADS)
Jorge, F. E.; Martins, L. S. C.; Franco, M. L.
2016-01-01
Segmented all-electron basis sets of valence double zeta quality plus polarization functions (DZP) for the elements from Ce to Lu are generated to be used with the non-relativistic and Douglas-Kroll-Hess (DKH) Hamiltonians. At the B3LYP level, the DZP-DKH atomic ionization energies and equilibrium bond lengths and atomization energies of the lanthanide trifluorides are evaluated and compared with benchmark theoretical and experimental data reported in the literature. In general, this compact size set shows to have a regular, efficient, and reliable performance. It can be particularly useful in molecular property calculations that require explicit treatment of the core electrons.
Xu, Xuefei; Truhlar, Donald G
2011-09-13
For molecules containing the fourth-period element arsenic, we test (i, ii) the accuracy of all-electron (AE) basis sets from the def2-xZVP and ma-xZVP series (where xZ is S, TZ, or QZ), (iii) the accuracy of the 6-311G series of AE basis sets with additional polarization and diffuse functions, and (iv) the performance of effective core potentials (ECPs). The first set of tests involves basis-set convergence studies with eleven density functionals for five cases: equilibrium dissociation energy (De) of As2, vertical ionization potential (VIP) of As2, IP of As, acid dissociation of H3AsO4, and De of FeAs. A second set of tests involves the same kinds of basis-set convergence studies for the VIP and De values of As3 and As4 clusters. Both relativistic and nonrelativistic calculations are considered, including in each case both AE calculations and calculations with ECPs. Convergence and accuracy are assessed by comparing to relativistic AE calculations with the cc-pV5Z-DK or ma-cc-pV5Z-DK basis and to nonrelativistic AE calculations with the cc-pV5Z or ma-cc-pV5Z basis. The primary objective of this study is to evaluate the abilities of ECPs with both their recommended basis sets and other basis sets to reproduce the results of all-electron relativistic calculations. The performance of the def2 and ma series basis sets is consistent with their sizes, and quadruple-ζ basis sets are the best. The def2-TZVP basis set performs better than most of the 6-311G series basis sets, which are the most commonly used basis sets in the previous studies of arsenic compounds. However, relativistic def2-TZVP calculations are not recommended. The large-core ECPs, which are the only available ECPs for arsenic in the popular Gaussian program, have average errors of 9-12 kcal/mol for the arsenic systems studied; therefore, these ECPs are not recommended. The triple-ζ small-core relativistic ECP (RECP) basis set cc-pVTZ-PP is found to have performance better than that of the def2-TZVP
Řezáč, Jan; de la Lande, Aurélien
2015-02-10
Separation of the energetic contribution of charge transfer to interaction energy in noncovalent complexes would provide important insight into the mechanisms of the interaction. However, the calculation of charge-transfer energy is not an easy task. It is not a physically well-defined term, and the results might depend on how it is described in practice. Commonly, the charge transfer is defined in terms of molecular orbitals; in this framework, however, the charge transfer vanishes as the basis set size increases toward the complete basis set limit. This can be avoided by defining the charge transfer in terms of the spatial extent of the electron densities of the interacting molecules, but the schemes used so far do not reflect the actual electronic structure of each particular system and thus are not reliable. We propose a spatial partitioning of the system, which is based on a charge transfer-free reference state, namely superimposition of electron densities of the noninteracting fragments. We show that this method, employing constrained DFT for the calculation of the charge-transfer energy, yields reliable results and is robust with respect to the strength of the charge transfer, the basis set size, and the DFT functional used. Because it is based on DFT, the method is applicable to rather large systems.
Ermler, Walter V.; Tilson, Jeffrey L.
2012-12-15
A procedure for structuring generally contracted valence-core/valence basis sets of Gaussian-type functions for use with relativistic effective core potentials (gcv-c/v-RECP basis sets) is presented. Large valence basis sets are enhanced using a compact basis set derived for outer core electrons in the presence of small-core RECPs. When core electrons are represented by relativistic effective core potentials (RECPs), and appropriate levels of theory, these basis sets are shown to provide accurate representations of atomic and molecular valence and outer-core electrons. Core/valence polarization and correlation effects can be calculated using these basis sets through standard methods for treating electron correlation. Calculations of energies and spectra for Ru, Os, Ir, In and Cs are reported. Spectroscopic constants for RuO2+, OsO2+, Cs2 and InH are calculated and compared with experiment.
NASA Astrophysics Data System (ADS)
Peterson, Kirk A.; Figgen, Detlev; Dolg, Michael; Stoll, Hermann
2007-03-01
Scalar-relativistic pseudopotentials and corresponding spin-orbit potentials of the energy-consistent variety have been adjusted for the simulation of the [Ar]3d10 cores of the 4d transition metal elements Y-Pd. These potentials have been determined in a one-step procedure using numerical two-component calculations so as to reproduce atomic valence spectra from four-component all-electron calculations. The latter have been performed at the multi-configuration Dirac-Hartree-Fock level, using the Dirac-Coulomb Hamiltonian and perturbatively including the Breit interaction. The derived pseudopotentials reproduce the all-electron reference data with an average accuracy of 0.03eV for configurational averages over nonrelativistic orbital configurations and 0.1eV for individual relativistic states. Basis sets following a correlation consistent prescription have also been developed to accompany the new pseudopotentials. These range in size from cc-pVDZ-PP to cc-pV5Z-PP and also include sets for 4s4p correlation (cc-pwCVDZ-PP through cc-pwCV5Z-PP), as well as those with extra diffuse functions (aug-cc-pVDZ-PP, etc.). In order to accurately assess the impact of the pseudopotential approximation, all-electron basis sets of triple-zeta quality have also been developed using the Douglas-Kroll-Hess Hamiltonian (cc-pVTZ-DK, cc-pwCVTZ-DK, and aug-cc-pVTZ-DK). Benchmark calculations of atomic ionization potentials and 4dm -25s2→4dm -15s1 electronic excitation energies are reported at the coupled cluster level of theory with extrapolations to the complete basis set limit.
Peterson, Kirk A; Figgen, Detlev; Dolg, Michael; Stoll, Hermann
2007-03-28
Scalar-relativistic pseudopotentials and corresponding spin-orbit potentials of the energy-consistent variety have been adjusted for the simulation of the [Ar]3d(10) cores of the 4d transition metal elements Y-Pd. These potentials have been determined in a one-step procedure using numerical two-component calculations so as to reproduce atomic valence spectra from four-component all-electron calculations. The latter have been performed at the multi-configuration Dirac-Hartree-Fock level, using the Dirac-Coulomb Hamiltonian and perturbatively including the Breit interaction. The derived pseudopotentials reproduce the all-electron reference data with an average accuracy of 0.03 eV for configurational averages over nonrelativistic orbital configurations and 0.1 eV for individual relativistic states. Basis sets following a correlation consistent prescription have also been developed to accompany the new pseudopotentials. These range in size from cc-pVDZ-PP to cc-pV5Z-PP and also include sets for 4s4p correlation (cc-pwCVDZ-PP through cc-pwCV5Z-PP), as well as those with extra diffuse functions (aug-cc-pVDZ-PP, etc.). In order to accurately assess the impact of the pseudopotential approximation, all-electron basis sets of triple-zeta quality have also been developed using the Douglas-Kroll-Hess Hamiltonian (cc-pVTZ-DK, cc-pwCVTZ-DK, and aug-cc-pVTZ-DK). Benchmark calculations of atomic ionization potentials and 4d(m-2)5s(2)-->4d(m-1)5s(1) electronic excitation energies are reported at the coupled cluster level of theory with extrapolations to the complete basis set limit. PMID:17411102
Witte, Jonathon; Neaton, Jeffrey B; Head-Gordon, Martin
2016-05-21
With the aim of systematically characterizing the convergence of common families of basis sets such that general recommendations for basis sets can be made, we have tested a wide variety of basis sets against complete-basis binding energies across the S22 set of intermolecular interactions-noncovalent interactions of small and medium-sized molecules consisting of first- and second-row atoms-with three distinct density functional approximations: SPW92, a form of local-density approximation; B3LYP, a global hybrid generalized gradient approximation; and B97M-V, a meta-generalized gradient approximation with nonlocal correlation. We have found that it is remarkably difficult to reach the basis set limit; for the methods and systems examined, the most complete basis is Jensen's pc-4. The Dunning correlation-consistent sequence of basis sets converges slowly relative to the Jensen sequence. The Karlsruhe basis sets are quite cost effective, particularly when a correction for basis set superposition error is applied: counterpoise-corrected def2-SVPD binding energies are better than corresponding energies computed in comparably sized Dunning and Jensen bases, and on par with uncorrected results in basis sets 3-4 times larger. These trends are exhibited regardless of the level of density functional approximation employed. A sense of the magnitude of the intrinsic incompleteness error of each basis set not only provides a foundation for guiding basis set choice in future studies but also facilitates quantitative comparison of existing studies on similar types of systems. PMID:27208948
Structural basis for inhibition of the histone chaperone activity of SET/TAF-Iβ by cytochrome c.
González-Arzola, Katiuska; Díaz-Moreno, Irene; Cano-González, Ana; Díaz-Quintana, Antonio; Velázquez-Campoy, Adrián; Moreno-Beltrán, Blas; López-Rivas, Abelardo; De la Rosa, Miguel A
2015-08-11
Chromatin is pivotal for regulation of the DNA damage process insofar as it influences access to DNA and serves as a DNA repair docking site. Recent works identify histone chaperones as key regulators of damaged chromatin's transcriptional activity. However, understanding how chaperones are modulated during DNA damage response is still challenging. This study reveals that the histone chaperone SET/TAF-Iβ interacts with cytochrome c following DNA damage. Specifically, cytochrome c is shown to be translocated into cell nuclei upon induction of DNA damage, but not upon stimulation of the death receptor or stress-induced pathways. Cytochrome c was found to competitively hinder binding of SET/TAF-Iβ to core histones, thereby locking its histone-binding domains and inhibiting its nucleosome assembly activity. In addition, we have used NMR spectroscopy, calorimetry, mutagenesis, and molecular docking to provide an insight into the structural features of the formation of the complex between cytochrome c and SET/TAF-Iβ. Overall, these findings establish a framework for understanding the molecular basis of cytochrome c-mediated blocking of SET/TAF-Iβ, which subsequently may facilitate the development of new drugs to silence the oncogenic effect of SET/TAF-Iβ's histone chaperone activity.
Structural basis for inhibition of the histone chaperone activity of SET/TAF-Iβ by cytochrome c
González-Arzola, Katiuska; Díaz-Moreno, Irene; Cano-González, Ana; Díaz-Quintana, Antonio; Velázquez-Campoy, Adrián; Moreno-Beltrán, Blas; López-Rivas, Abelardo; De la Rosa, Miguel A.
2015-01-01
Chromatin is pivotal for regulation of the DNA damage process insofar as it influences access to DNA and serves as a DNA repair docking site. Recent works identify histone chaperones as key regulators of damaged chromatin’s transcriptional activity. However, understanding how chaperones are modulated during DNA damage response is still challenging. This study reveals that the histone chaperone SET/TAF-Iβ interacts with cytochrome c following DNA damage. Specifically, cytochrome c is shown to be translocated into cell nuclei upon induction of DNA damage, but not upon stimulation of the death receptor or stress-induced pathways. Cytochrome c was found to competitively hinder binding of SET/TAF-Iβ to core histones, thereby locking its histone-binding domains and inhibiting its nucleosome assembly activity. In addition, we have used NMR spectroscopy, calorimetry, mutagenesis, and molecular docking to provide an insight into the structural features of the formation of the complex between cytochrome c and SET/TAF-Iβ. Overall, these findings establish a framework for understanding the molecular basis of cytochrome c-mediated blocking of SET/TAF-Iβ, which subsequently may facilitate the development of new drugs to silence the oncogenic effect of SET/TAF-Iβ’s histone chaperone activity. PMID:26216969
Structural basis for inhibition of the histone chaperone activity of SET/TAF-Iβ by cytochrome c.
González-Arzola, Katiuska; Díaz-Moreno, Irene; Cano-González, Ana; Díaz-Quintana, Antonio; Velázquez-Campoy, Adrián; Moreno-Beltrán, Blas; López-Rivas, Abelardo; De la Rosa, Miguel A
2015-08-11
Chromatin is pivotal for regulation of the DNA damage process insofar as it influences access to DNA and serves as a DNA repair docking site. Recent works identify histone chaperones as key regulators of damaged chromatin's transcriptional activity. However, understanding how chaperones are modulated during DNA damage response is still challenging. This study reveals that the histone chaperone SET/TAF-Iβ interacts with cytochrome c following DNA damage. Specifically, cytochrome c is shown to be translocated into cell nuclei upon induction of DNA damage, but not upon stimulation of the death receptor or stress-induced pathways. Cytochrome c was found to competitively hinder binding of SET/TAF-Iβ to core histones, thereby locking its histone-binding domains and inhibiting its nucleosome assembly activity. In addition, we have used NMR spectroscopy, calorimetry, mutagenesis, and molecular docking to provide an insight into the structural features of the formation of the complex between cytochrome c and SET/TAF-Iβ. Overall, these findings establish a framework for understanding the molecular basis of cytochrome c-mediated blocking of SET/TAF-Iβ, which subsequently may facilitate the development of new drugs to silence the oncogenic effect of SET/TAF-Iβ's histone chaperone activity. PMID:26216969
NASA Astrophysics Data System (ADS)
Simon, Sílvia; Duran, Miquel
1997-08-01
Quantum molecular similarity (QMS) techniques are used to assess the response of the electron density of various small molecules to application of a static, uniform electric field. Likewise, QMS is used to analyze the changes in electron density generated by the process of floating a basis set. The results obtained show an interrelation between the floating process, the optimum geometry, and the presence of an external field. Cases involving the Le Chatelier principle are discussed, and an insight on the changes of bond critical point properties, self-similarity values and density differences is performed.
Basis-set limit binding energies of Be{sub n} and Mg{sub n} (n=2,3,4) clusters
Lee, Jae Shin
2003-10-01
The general applicability of the basis set and correlation-dependent extrapolation method [J. Chem. Phys. 118, 3035 (2003)], which fits two successive correlation energies with correlation-consistent cc-pVXZ and cc-pV(X+1)Z basis sets [X=D(2),T(3),Q(4)] by (X+k){sup -3} with varying k according to basis-set quality and correlation level, was explored by examining the basis-set limit binding energies of the metallic clusters of Be{sub n} and Mg{sub n} (n=2,3,4) at the MP2 (second-order Moller-Plesset perturbation theory) and CCSD(T) (single and double coupled cluster method with perturbative triple correction) level. The comparison of the extrapolated basis-set limit estimates with the highly accurate reference basis-set limits suggests that the extrapolation of correlation contributions of binding energies with only cc-pVDZ and cc-pVTZ basis sets already yields the basis-set limit estimates close to the reference complete basis-set limits within 1 m-hartree in most cases, signifying the utility of this extrapolation method in the study of larger clusters. The natural extension of this extrapolation method to all electron correlated computations including core electrons with core-valence cc-pCVXZ basis sets is also made, which shows the similar accuracy of the extrapolated estimates for all electron correlated results as the valence electron only correlated results. The comparison of the MP2 and CCSD(T) basis-set limit binding energies with DFT (density-functional theory) results manifests the capability and limitation of the current DFT methods in studying the binding of such clusters.
Yao, Y. X.; Wang, C. Z.; Ho, K. M.
2010-06-16
A chemical bonding scheme is presented for the analysis of solid-state systems. The scheme is based on the intrinsic oriented quasiatomic minimal-basis-set orbitals (IO-QUAMBOs) previously developed by Ivanic and Ruedenberg for molecular systems. In the solid-state scheme, IO-QUAMBOs are generated by a unitary transformation of the quasiatomic orbitals located at each site of the system with the criteria of maximizing the sum of the fourth power of interatomic orbital bond order. Possible bonding and antibonding characters are indicated by the single particle matrix elements, and can be further examined by the projected density of states. We demonstrate the method by applications to graphene and (6,0) zigzag carbon nanotube. The oriented-orbital scheme automatically describes the system in terms of sp{sup 2} hybridization. The effect of curvature on the electronic structure of the zigzag carbon nanotube is also manifested in the deformation of the intrinsic oriented orbitals as well as a breaking of symmetry leading to nonzero single particle density matrix elements. In an additional study, the analysis is performed on the Al{sub 3}V compound. The main covalent bonding characters are identified in a straightforward way without resorting to the symmetry analysis. Our method provides a general way for chemical bonding analysis of ab initio electronic structure calculations with any type of basis sets.
Orbital-specific mapping of chemical dynamics with ultrafast x-rays
NASA Astrophysics Data System (ADS)
Wernet, Philippe
Charge and spin density changes at the metal sites of transition-metal complexes and in metalloproteins determine reactivity and selectivity. To understand their function and to optimize complexes for photocatalytic applications the changes of charge and spin densities need to be mapped and ultimately controlled. I will discuss how time-resolved soft x-ray spectroscopy enables a fundamental understanding of local atomic and intermolecular interactions and their dynamics on atomic length and time scales of Ångströms and femtoseconds. The approach consists in using time-resolved, atom- and orbital-specific x-ray spectroscopy and quantum chemical theory to map the frontier-orbital interactions and their evolution in real time of ultrafast chemical transformations. We recently used femtosecond resonant inelastic x-ray scattering (RIXS, the x-ray analog of resonant Raman scattering) at the x-ray free-electron laser LINAC Coherent Light Source (LCLS, Stanford, USA) to probe the reaction dynamics of a transition-metal complex in solution on the femtosecond time scale. Spin crossover and ligation are found to define the excited-state dynamics. It is demonstrated how correlating orbital symmetry and orbital interactions with spin multiplicity allows for determining the reactivity of short-lived reaction intermediates. I will discuss how this complements approaches that probe structural dynamics and how it can be extended to map the local chemical interactions and their dynamical evolution in metalloproteins.
NASA Astrophysics Data System (ADS)
Thomas, Patrick Ryan
Large simulation cell sizes, relativistic effects, and the need to correctly model excited state properties are major impediments to the accurate prediction of the optical properties of candidate materials for solid-state laser crystal and luminescent applications. To overcome these challenges, new methods must be created to improve the electron orbital wavefunction and interactions. In this work, a method has been developed to create new analytical four-component, fully-relativistic and single-component scalar relativistic descriptions of the atomic orbital wave functions from Grasp2K numerically represented atomic orbitals. In addition, adapted theory for the calculation of the relativistic kinetic energy contribution to Hamiltonian which bypasses directly solving the Dirac equation has been explicated. The orbital description improvements are tested against YAG, YBCO, SnO2 and BiF3. The improvements to the basis set reflect an improvement in both computational speed and accuracy.
NASA Astrophysics Data System (ADS)
Guan, Qingze; Blume, Doerte
2016-05-01
The explicit correlated Gaussian (ECG) basis set expansion approach is a variational approach that has been used in various areas, including molecular, nuclear, atomic, and chemical physics. In the world of cold atoms, e.g., the ECG approach has been used to calculate the eigenenergies and eigenstates of few-body systems governed by Efimov physics. Since the first experimental realization of synthesized gauge fields, few-body systems with spin-orbit coupling have attracted a great deal of attention. Here, the ECG approach is customized to few-body systems with both short-range interactions and spin-orbit couplings. Benchmark tests and a performance analysis will be presented. Support by the NSF is gratefully acknowledged.
Many-body basis-set reduction applied to the two-dimensional t-Jz model
NASA Astrophysics Data System (ADS)
Riera, J.; Dagotto, E.
1993-06-01
A simple variation of the Lanczos method is discussed. The technique is based on a systematic reduction of the size of the Hilbert space of the model under consideration, and it has many similarities with the basis-set-reduction approach recently introduced by Wenzel and Wilson in the context of quantum chemistry. As an example, the two-dimensional t-Jz model of strongly correlated electrons is studied. Accurate results for the ground-state energy can be obtained on clusters of up to 50 sites, which are unreachable by conventional Lanczos approaches. In particular, the energy of one and two holes is analyzed as a function of Jz/t. In the bulk limit, the numerical results suggest that a finite coupling Jz/t]c~0.18 is necessary to induce ``binding'' of holes in the model.
Andrade, Xavier; Aspuru-Guzik, Alán
2013-10-01
We discuss the application of graphical processing units (GPUs) to accelerate real-space density functional theory (DFT) calculations. To make our implementation efficient, we have developed a scheme to expose the data parallelism available in the DFT approach; this is applied to the different procedures required for a real-space DFT calculation. We present results for current-generation GPUs from AMD and Nvidia, which show that our scheme, implemented in the free code Octopus, can reach a sustained performance of up to 90 GFlops for a single GPU, representing a significant speed-up when compared to the CPU version of the code. Moreover, for some systems, our implementation can outperform a GPU Gaussian basis set code, showing that the real-space approach is a competitive alternative for DFT simulations on GPUs. PMID:26589153
Chacon-Madrid, Heber J; Murphy, Benjamin N; Pandis, Spyros N; Donahue, Neil M
2012-10-16
We use a two-dimensional volatility basis set (2D-VBS) box model to simulate secondary organic aerosol (SOA) mass yields of linear oxygenated molecules: n-tridecanal, 2- and 7-tridecanone, 2- and 7-tridecanol, and n-pentadecane. A hybrid model with explicit, a priori treatment of the first-generation products for each precursor molecule, followed by a generic 2D-VBS mechanism for later-generation chemistry, results in excellent model-measurement agreement. This strongly confirms that the 2D-VBS mechanism is a predictive tool for SOA modeling but also suggests that certain important first-generation products for major primary SOA precursors should be treated explicitly for optimal SOA predictions.
Andrade, Xavier; Aspuru-Guzik, Alán
2013-10-01
We discuss the application of graphical processing units (GPUs) to accelerate real-space density functional theory (DFT) calculations. To make our implementation efficient, we have developed a scheme to expose the data parallelism available in the DFT approach; this is applied to the different procedures required for a real-space DFT calculation. We present results for current-generation GPUs from AMD and Nvidia, which show that our scheme, implemented in the free code Octopus, can reach a sustained performance of up to 90 GFlops for a single GPU, representing a significant speed-up when compared to the CPU version of the code. Moreover, for some systems, our implementation can outperform a GPU Gaussian basis set code, showing that the real-space approach is a competitive alternative for DFT simulations on GPUs.
NASA Astrophysics Data System (ADS)
Oberhofer, Harald; Blumberger, Jochen
2010-12-01
We present a plane wave basis set implementation for the calculation of electronic coupling matrix elements of electron transfer reactions within the framework of constrained density functional theory (CDFT). Following the work of Wu and Van Voorhis [J. Chem. Phys. 125, 164105 (2006)], the diabatic wavefunctions are approximated by the Kohn-Sham determinants obtained from CDFT calculations, and the coupling matrix element calculated by an efficient integration scheme. Our results for intermolecular electron transfer in small systems agree very well with high-level ab initio calculations based on generalized Mulliken-Hush theory, and with previous local basis set CDFT calculations. The effect of thermal fluctuations on the coupling matrix element is demonstrated for intramolecular electron transfer in the tetrathiafulvalene-diquinone (Q-TTF-Q-) anion. Sampling the electronic coupling along density functional based molecular dynamics trajectories, we find that thermal fluctuations, in particular the slow bending motion of the molecule, can lead to changes in the instantaneous electron transfer rate by more than an order of magnitude. The thermal average, ( {< {| {H_ab } |^2 } > } )^{1/2} = 6.7 {mH}, is significantly higher than the value obtained for the minimum energy structure, | {H_ab } | = 3.8 {mH}. While CDFT in combination with generalized gradient approximation (GGA) functionals describes the intermolecular electron transfer in the studied systems well, exact exchange is required for Q-TTF-Q- in order to obtain coupling matrix elements in agreement with experiment (3.9 mH). The implementation presented opens up the possibility to compute electronic coupling matrix elements for extended systems where donor, acceptor, and the environment are treated at the quantum mechanical (QM) level.
Cignetti, Fabien; Salvia, Emilie; Anton, Jean-Luc; Grosbras, Marie-Hélène; Assaiante, Christine
2016-01-01
Conventional analysis of functional magnetic resonance imaging (fMRI) data using the general linear model (GLM) employs a neural model convolved with a canonical hemodynamic response function (HRF) peaking 5 s after stimulation. Incorporation of a further basis function, namely the canonical HRF temporal derivative, accounts for delays in the hemodynamic response to neural activity. A population that may benefit from this flexible approach is children whose hemodynamic response is not yet mature. Here, we examined the effects of using the set based on the canonical HRF plus its temporal derivative on both first- and second-level GLM analyses, through simulations and using developmental data (an fMRI dataset on proprioceptive mapping in children and adults). Simulations of delayed fMRI first-level data emphasized the benefit of carrying forward to the second-level a derivative boost that combines derivative and nonderivative beta estimates. In the experimental data, second-level analysis using a paired t-test showed increased mean amplitude estimate (i.e., increased group contrast mean) in several brain regions related to proprioceptive processing when using the derivative boost compared to using only the nonderivative term. This was true especially in children. However, carrying forward to the second-level the individual derivative boosts had adverse consequences on random-effects analysis that implemented one-sample t-test, yielding increased between-subject variance, thus affecting group-level statistic. Boosted data also presented a lower level of smoothness that had implication for the detection of group average activation. Imposing soft constraints on the derivative boost by limiting the time-to-peak range of the modeled response within a specified range (i.e., 4–6 s) mitigated these issues. These findings support the notion that there are pros and cons to using the informed basis set with developmental data. PMID:27471441
Fletcher, Jordan M; Boyle, Aimee L; Bruning, Marc; Bartlett, Gail J; Vincent, Thomas L; Zaccai, Nathan R; Armstrong, Craig T; Bromley, Elizabeth H C; Booth, Paula J; Brady, R Leo; Thomson, Andrew R; Woolfson, Derek N
2012-06-15
Protein engineering, chemical biology, and synthetic biology would benefit from toolkits of peptide and protein components that could be exchanged reliably between systems while maintaining their structural and functional integrity. Ideally, such components should be highly defined and predictable in all respects of sequence, structure, stability, interactions, and function. To establish one such toolkit, here we present a basis set of de novo designed α-helical coiled-coil peptides that adopt defined and well-characterized parallel dimeric, trimeric, and tetrameric states. The designs are based on sequence-to-structure relationships both from the literature and analysis of a database of known coiled-coil X-ray crystal structures. These give foreground sequences to specify the targeted oligomer state. A key feature of the design process is that sequence positions outside of these sites are considered non-essential for structural specificity; as such, they are referred to as the background, are kept non-descript, and are available for mutation as required later. Synthetic peptides were characterized in solution by circular-dichroism spectroscopy and analytical ultracentrifugation, and their structures were determined by X-ray crystallography. Intriguingly, a hitherto widely used empirical rule-of-thumb for coiled-coil dimer specification does not hold in the designed system. However, the desired oligomeric state is achieved by database-informed redesign of that particular foreground and confirmed experimentally. We envisage that the basis set will be of use in directing and controlling protein assembly, with potential applications in chemical and synthetic biology. To help with such endeavors, we introduce Pcomp, an on-line registry of peptide components for protein-design and synthetic-biology applications. PMID:23651206
Cignetti, Fabien; Salvia, Emilie; Anton, Jean-Luc; Grosbras, Marie-Hélène; Assaiante, Christine
2016-01-01
Conventional analysis of functional magnetic resonance imaging (fMRI) data using the general linear model (GLM) employs a neural model convolved with a canonical hemodynamic response function (HRF) peaking 5 s after stimulation. Incorporation of a further basis function, namely the canonical HRF temporal derivative, accounts for delays in the hemodynamic response to neural activity. A population that may benefit from this flexible approach is children whose hemodynamic response is not yet mature. Here, we examined the effects of using the set based on the canonical HRF plus its temporal derivative on both first- and second-level GLM analyses, through simulations and using developmental data (an fMRI dataset on proprioceptive mapping in children and adults). Simulations of delayed fMRI first-level data emphasized the benefit of carrying forward to the second-level a derivative boost that combines derivative and nonderivative beta estimates. In the experimental data, second-level analysis using a paired t-test showed increased mean amplitude estimate (i.e., increased group contrast mean) in several brain regions related to proprioceptive processing when using the derivative boost compared to using only the nonderivative term. This was true especially in children. However, carrying forward to the second-level the individual derivative boosts had adverse consequences on random-effects analysis that implemented one-sample t-test, yielding increased between-subject variance, thus affecting group-level statistic. Boosted data also presented a lower level of smoothness that had implication for the detection of group average activation. Imposing soft constraints on the derivative boost by limiting the time-to-peak range of the modeled response within a specified range (i.e., 4-6 s) mitigated these issues. These findings support the notion that there are pros and cons to using the informed basis set with developmental data.
NASA Technical Reports Server (NTRS)
Mackenzie, Anne I.; Baginski, Michael E.; Rao, Sadasiva M.
2008-01-01
In this work, we present an alternate set of basis functions, each defined over a pair of planar triangular patches, for the method of moments solution of electromagnetic scattering and radiation problems associated with arbitrarily-shaped, closed, conducting surfaces. The present basis functions are point-wise orthogonal to the pulse basis functions previously defined. The prime motivation to develop the present set of basis functions is to utilize them for the electromagnetic solution of dielectric bodies using a surface integral equation formulation which involves both electric and magnetic cur- rents. However, in the present work, only the conducting body solution is presented and compared with other data.
NASA Astrophysics Data System (ADS)
Edmondson, Richard; Rodgers, Michael
2008-04-01
Using matched filters to find targets in cluttered images is an old idea. Human operators can interactively find threshold values to be applied to the correlation surface that will do a good job of binarizing it into signal/non-signal pixel regions. Automating the thresholding process with nine measured image statistics is the goal of this paper. The nine values are the mean, maximum, and standard deviation of three images: the input image presumed to have some signal, an NxN matched filter kernel in the shape of the signal, and the correlation surface generated by convolving the input image with the matched filter kernel. Several thousand input images with known target locations and reference images were run through a correlator with kernels that resembled the targets. The nine numbers referred to above were calculated in addition to a threshold found with a time consuming brutal algorithm. Multidimensional radial basis functions were associated with each nine number set. The bump height corresponded to the threshold value. The bump location was within a nine dimensional hypercube corresponding to the nine numbers scaled so that all the data fell within the interval 0 to 1 on each axis. The sigma (sharpness of the radial basis function) was calculated as a fraction of the squared distance to the closest neighboring bump. A new threshold is calculated as a weighted sum of all the Gaussian bumps in the vicinity of the input 9D vector. The paper will conclude with a table of results using this method compared to other methods.
NASA Astrophysics Data System (ADS)
Maroulis, George
1998-06-01
A large (18s 13p 8d 5f / 12s 7p 3d 2f) basis set consisting of 256 uncontracted gaussian-type functions is expected to yield values near the Hartree-Fock limit for the static hyperpolarizability of H 2O: βzxx=-9.40, βzyy=-1.35, βzzz=-7.71 and β¯=-11.07 for βαβγ ( e3a03Eh-2) and γxxxx=569, γyyyy=1422, γzzzz=907, γxxyy=338, γyyzz=389, γzzxx=287 and γ¯=985 for γαβγδ ( e4a04Eh-3) at the experimental equilibrium geometry (with z as the C 2 axis, molecule on the xz plane). The respective electron correlation corrections obtained with the single, double and perturbatively linked triple excitations coupled-cluster method and a [9s 6p 6d 3f / 6s 4p 2d 1f] basis set are βzxx=-0.45, βzyy=-4.19, βzzz=-6.09, β¯=-6.44 and γxxxx=267, γyyyy=1228, γzzzz=574, γxxyy=295, γyyzz=322, γzzxx=152, γ¯=721 . For the static limit we propose β¯=-17.5±0.3 e3a03Eh-2 and γ¯=(171±6)×10 1e4a04Eh-3, in near agreement with the experimental findings of β¯=-19.2±0.9 e3a03Eh-2 and γ¯=1800±150 e4a04Eh-3 deduced from EFISH measurements at 1064 nm by Kaatz et al. [P. Kaatz, E.A. Donley, D.P. Shelton, J. Chem. Phys. 108 (1998) 849].
Code of Federal Regulations, 2010 CFR
2010-01-01
... REGULATIONS PROCEDURES FOR REIMBURSEMENT OF GENERAL AVIATION OPERATORS AND SERVICE PROVIDERS IN THE WASHINGTON, DC AREA Set-Aside for Operators or Providers at Certain Airports § 331.35 What is the basis...
Gusso, Michele
2008-01-28
A detailed study on the accuracy attainable with numerical atomic orbitals in the context of pseudopotential first-principles density functional theory is presented. Dimers of first- and second-row elements are analyzed: bond lengths, atomization energies, and Kohn-Sham eigenvalue spectra obtained with localized orbitals and with plane-wave basis sets are compared. For each dimer, the cutoff radius, the shape, and the number of the atomic basis orbitals are varied in order to maximize the accuracy of the calculations. Optimized atomic orbitals are obtained following two routes: (i) maximization of the projection of plane wave results into atomic orbital basis sets and (ii) minimization of the total energy with respect to a set of primitive atomic orbitals as implemented in the OPENMX software package. It is found that by optimizing the numerical basis, chemical accuracy can be obtained even with a small set of orbitals.
Buczek, Aneta; Kupka, Teobald; Broda, Małgorzata A; Żyła, Adriana
2016-01-01
In this work, regular convergence patterns of the structural, harmonic, and VPT2-calculated anharmonic vibrational parameters of ethylene towards the Kohn-Sham complete basis set (KS CBS) limit are demonstrated for the first time. The performance of the VPT2 scheme implemented using density functional theory (DFT-BLYP and DFT-B3LYP) in combination with two Pople basis sets (6-311++G** and 6-311++G(3df,2pd)), the polarization-consistent basis sets pc-n, aug-pc-n, and pcseg-n (n = 0, 1, 2, 3, 4), and the correlation-consistent basis sets cc-pVXZ and aug-cc-pVXZ (X = D, T, Q, 5, 6) was tested.The BLYP-calculated harmonic frequencies were found to be markedly closer than the B3LYP-calculated harmonic frequencies to the experimentally derived values, while the calculated anharmonic frequencies consistently underestimated the observed wavenumbers. The different basis set families gave very similar estimated values for the CBS parameters. The anharmonic frequencies calculated with B3LYP/aug-pc-3 were consistently significantly higher than those obtained with the pc-3 basis set; applying the aug-pcseg-n basis set family alleviated this problem. Utilization of B3LYP/aug-pcseg-n basis sets instead of B3LYP/aug-cc-pVXZ, which is computationally less expensive, is suggested for medium-sized molecules. Harmonic BLYP/pc-2 calculations produced fairly accurate ethylene frequencies. Graphical Abstract In this study, the performance of the VPT2 scheme implemented using density functional theory (DFT-BLYP and DFT-B3LYP) in combination with the polarization-consistent basis sets pc-n, aug-pc-n, and pcseg-n (n = 0, 1, 2, 3, 4), and the correlation-consistent basis sets cc-pVXZ and aug-cc-pVXZ (X = D, T, Q, 5, and 6) was tested. For the first time, we demonstrated regular convergence patterns of the structural, harmonic, and VPT2-calculated anharmonic vibrational parameters of ethylene towards the Kohn-Sham complete basis set (KS CBS) limit.
A new complete basis set model (CBS-QB3) study on the possible intermediates in chemiluminescence
NASA Astrophysics Data System (ADS)
Zhang, Yong; Zeng, Xi-Rui; You, Xiao-Zeng
2000-11-01
The new highly accurate complete basis set model, CBS-QB3, was employed here to elucidate the long experimentally discussed problem in a general class of chemiluminescent reactions involving peroxyoxalate systems. Both the stability comparison and the vibrational spectra favor that the intermediate is better to be recognized as the cyclic singlet 1,2-dioxetanedione with the C2v symmetry, which verifies the experimental suggestion yet provides more characterization information. Another two kinds of minimum species in its potential energy surface (PES) are two kinds of product: (1) two carbon dioxide and (2) two carbon monoxide and one oxygen, where the thermodynamic parameters correctly identify their relative yield in the experiment—the former is much more abundant than the latter. In a complete search of minimum states in its PES, the triplet C2v and D2h states were found, which is energetically unfavorable compared with the singlet C2v state. Their vibrational data also support some experimental conclusions of ruling out a radical intermediate. In contrast, the singlet D2h state was found to be a transition state for the "up" and "down" singlet C2v states. The complete active space self-consistent-field calculations with the second-order Möller-Plesset correlation energy correction also support that the most stable species is the singlet C2v state and the singlet D2h state is more energetically favorable than its triplet counterpart.
Kitamura, Hikaru
2013-02-13
Photoabsorption cross-sections of simple metals are formulated through a solid-state band theory based on the orthogonalized-plane-wave (OPW) method in Slater's local-exchange approximation, where interband transitions of core and conduction electrons are evaluated up to the soft x-ray regime by using large basis sets. The photoabsorption cross-sections of a sodium crystal are computed for a wide photon energy range from 3 to 1800 eV. It is found that the numerical results reproduce the existing x-ray databases fairly well for energies above the L(2,3)-edge (31 eV), verifying a consistency between solid-state and atomic models for inner-shell photoabsorption; additional oscillatory structures in the present spectra manifest solid-state effects. Our computed results in the vacuum ultraviolet regime (6-30 eV) are also in better agreement with experimental data compared to earlier theories, although some discrepancies remain in the range of 20-30 eV. The influence of the core eigenvalues on the absorption spectra is examined. PMID:23334229
Valeev, Edward F; Janssen, Curtis L
2004-07-15
Ab initio electronic structure approaches in which electron correlation explicitly appears have been the subject of much recent interest. Because these methods accelerate the rate of convergence of the energy and properties with respect to the size of the one-particle basis set, they promise to make accuracies of better than 1 kcal/mol computationally feasible for larger chemical systems than can be treated at present with such accuracy. The linear R12 methods of Kutzelnigg and co-workers are currently the most practical means to include explicit electron correlation. However, the application of such methods to systems of chemical interest faces severe challenges, most importantly, the still steep computational cost of such methods. Here we describe an implementation of the second-order Møller-Plesset method with terms linear in the interelectronic distances (MP2-R12) which has a reduced computational cost due to the use of two basis sets. The use of two basis sets in MP2-R12 theory was first investigated recently by Klopper and Samson and is known as the auxiliary basis set (ABS) approach. One of the basis sets is used to describe the orbitals and another, the auxiliary basis set, is used for approximating matrix elements occurring in the exact MP2-R12 theory. We further extend the applicability of the approach by parallelizing all steps of the integral-direct MP2-R12 energy algorithm. We discuss several variants of the MP2-R12 method in the context of parallel execution and demonstrate that our implementation runs efficiently on a variety of distributed memory machines. Results of preliminary applications indicate that the two-basis (ABS) MP2-R12 approach cannot be used safely when small basis sets (such as augmented double- and triple-zeta correlation consistent basis sets) are utilized in the orbital expansion. Our results suggest that basis set reoptimization or further modifications of the explicitly correlated ansatz and/or standard approximations for
Teodoro, Tiago Quevedo; da Silva, Albérico Borges Ferreira; Haiduke, Roberto Luiz Andrade
2014-09-01
This study reports a new relativistic prolapse-free Gaussian basis set series of quadruple-ζ quality, RPF-4Z, and an augmented version that includes extra diffuse functions, aug-RPF-4Z, for all the s- and p-block elements. The relativistic adapted Gaussian basis sets (RAGBSs), which are free of variational prolapse, were used as the starting primitive sets. Exponents of correlating/polarization functions were taken from a polynomial version of the generator coordinate Dirac-Fock (p-GCDF) method, in which the previously optimized RAGBS parameters are applied. By using such procedure we aimed to reduce the computational demand of these sets in comparison with fully optimized ones. The effect of these basis set increments on the correlation energy was evaluated by atomic multireference configuration interaction calculations with single and double excitations out of the valence shell. Finally, atomic and molecular calculations of fundamental properties (bond lengths, vibrational frequencies, dipole moments and electron affinities) corroborate the quadruple-ζ quality of these new sets that are also about half-time-consuming than the correspondent Dyall's v4z sets. The read-to use format of these (aug-)RPF-4Fz sets are available as Supporting Information files and can also be found at http://basis-sets.iqsc.usp.br/ . PMID:26588525
NASA Astrophysics Data System (ADS)
Brandbyge, Mads
2014-05-01
In a recent paper Reuter and Harrison [J. Chem. Phys. 139, 114104 (2013)] question the widely used mean-field electron transport theories, which employ nonorthogonal localized basis sets. They claim these can violate an "implicit decoupling assumption," leading to wrong results for the current, different from what would be obtained by using an orthogonal basis, and dividing surfaces defined in real-space. We argue that this assumption is not required to be fulfilled to get exact results. We show how the current/transmission calculated by the standard Greens function method is independent of whether or not the chosen basis set is nonorthogonal, and that the current for a given basis set is consistent with divisions in real space. The ambiguity known from charge population analysis for nonorthogonal bases does not carry over to calculations of charge flux.
Paschoal, Diego; Marcial, Bruna L; Lopes, Juliana Fedoce; De Almeida, Wagner B; Dos Santos, Hélio F
2012-11-01
In this article, we conducted an extensive ab initio study on the importance of the level of theory and the basis set for theoretical predictions of the structure and reactivity of cisplatin [cis-diamminedichloroplatinum(II) (cDDP)]. Initially, the role of the basis set for the Pt atom was assessed using 24 different basis sets, including three all-electron basis sets (ABS). In addition, a modified all-electron double zeta polarized basis set (mDZP) was proposed by adding a set of diffuse d functions onto the existing DZP basis set. The energy barrier and the rate constant for the first chloride/water exchange ligand process, namely, the aquation reaction, were taken as benchmarks for which reliable experimental data are available. At the B3LYP/mDZP/6-31+G(d) level (the first basis set is for Pt and the last set is for all of the light atoms), the energy barrier was 22.8 kcal mol(-1), which is in agreement with the average experimental value, 22.9 ± 0.4 kcal mol(-1). For the other accessible ABS (DZP and ADZP), the corresponding values were 15.4 and 24.5 kcal mol(-1), respectively. The ADZP and mDZP are notably similar, raising the importance of diffuse d functions for the prediction of the kinetic properties of cDDP. In this article, we also analyze the ligand basis set and the level of theory effects by considering 36 basis sets at distinct levels of theory, namely, Hartree-Fock, MP2, and several DFT functionals. From a survey of the data, we recommend the mPW1PW91/mDZP/6-31+G(d) or B3PW91/mDZP/6-31+G(d) levels to describe the structure and reactivity of cDDP and its small derivatives. Conversely, for large molecules containing a cisplatin motif (for example, the cDDP-DNA complex), the lower levels B3LYP/LANL2DZ/6-31+G(d) and B3LYP/SBKJC-VDZ/6-31+G(d) are suggested. At these levels of theory, the predicted energy barrier was 26.0 and 25.9 kcal mol(-1), respectively, which is only 13% higher than the actual value.
NASA Astrophysics Data System (ADS)
Rastak, Narges; Riipinen, Ilona; Pandis, Spyros
2015-04-01
INTRODUCTION Organic aerosol particles often consist of thousands of compounds with different properties. One of these properties is solubility, which affects the hygroscopic growth and CCN activation of the organic particles. Here we investigate the CCN activation behavior of complex organic aerosols accounting for the distribution of solubilities present in these mixtures. METHODS We considered a monodisperse population of spherical aerosol particles consisting of an internal mixture of organic compounds. When exposed to water vapor, these particles were assumed to grow reaching a thermodynamic equilibrium between the water vapor and the particle phase. The composition of the organic and aqueous phases was determined on one hand by the equilibrium between the aqueous phase and water vapor, and on the other hand by the equilibrium of the aqueous phase with the organic insoluble phase. We modelled the mixtures with the help of a solubility basis set (SBS, analogous to the volatility basis set VBS, Donahue et al. 2006, 2011, 2012), describing the mixture with n surrogate compounds with varying solubilities. We varied the range and shape of the solubility distribution, and the number of components n in the distribution, we also assumed two different kinds of interactions between the organic compounds in the insoluble phase 1) ideal mixture, where organics limit each other's dissolution; 2) unity activity, where organics behave as pure compounds and do not influence each other's dissolution. Critical supersaturations and the dissolution behavior at the point of CCN activation were calculated utilizing the Köhler theory for all organic mixtures (denoted here as the "full model"). The full model predictions were compared with the three simplified models: 1) assuming complete dissolution of all compounds; 2) treating the organic mixture solubility with the hygroscopicity parameter κ and 3) assuming a fixed soluble fraction ɛ for each mixture. RESULTS AND CONCLUSIONS
The route to MBxNyCz molecular wheels: II. Results using accurate functionals and basis sets
NASA Astrophysics Data System (ADS)
Güthler, A.; Mukhopadhyay, S.; Pandey, R.; Boustani, I.
2014-04-01
Applying ab initio quantum chemical methods, molecular wheels composed of metal and light atoms were investigated. High quality basis sets 6-31G*, TZPV, and cc-pVTZ as well as exchange and non-local correlation functionals B3LYP, BP86 and B3P86 were used. The ground-state energy and structures of cyclic planar and pyramidal clusters TiBn (for n = 3-10) were computed. In addition, the relative stability and electronic structures of molecular wheels TiBxNyCz (for x, y, z = 0-10) and MBnC10-n (for n = 2 to 5 and M = Sc to Zn) were determined. This paper sustains a follow-up study to the previous one of Boustani and Pandey [Solid State Sci. 14 (2012) 1591], in which the calculations were carried out at the HF-SCF/STO3G/6-31G level of theory to determine the initial stability and properties. The results show that there is a competition between the 2D planar and the 3D pyramidal TiBn clusters (for n = 3-8). Different isomers of TiB10 clusters were also studied and a structural transition of 3D-isomer into 2D-wheel is presented. Substitution boron in TiB10 by carbon or/and nitrogen atoms enhances the stability and leads toward the most stable wheel TiB3C7. Furthermore, the computations show that Sc, Ti and V at the center of the molecular wheels are energetically favored over other transition metal atoms of the first row.
Berski, Slawomir; Latajka, Zdzislaw; Gordon, Agnieszka J
2010-11-15
The article focus on the isomerization of nitrous acid HONO to hydrogen nitryl HNO(2). Density functional (B3LYP) and MP2 methods, and a wide variety of basis sets, have been chosen to investigate the mechanism of this reaction. The results clearly show that there are two possible paths: 1) Uncatalysed isomerisation, trans-HONO --> HNO(2), involving 1,2-hydrogen shift and characterized by a large energetic barrier 49.7 divided by 58.9 kcal/mol, 2) Catalysed double hydrogen transfer process, trans-HONO + cis-HONO --> HNO(2) + cis-HONO, which displays a significantly lower energetic barrier in a range of 11.6 divided by 18.9 kcal/mol. Topological analysis of the Electron Localization Function (ELF) shows that the hydrogen transfer for both studied reactions takes place through the formation of a 'dressed' proton along the reaction path. Use of a wide variety of basis sets demonstrates a clear basis set dependence on the ELF topology of HNO(2). Less saturated basis sets yield two lone pair basins, V(1)(N), V(2)(N), whereas more saturated ones (for example aug-cc-pVTZ and aug-cc-pVQZ) do not indicate a lone pair on the nitrogen atom. Topological analysis of the Electron Localizability Indication (ELI-D) at the CASSCF (12,10) confirms these findings, showing the existence of the lone pair basins but with decreasing populations as the basis set becomes more saturated (0.35e for the cc-pVDZ basis set to 0.06e for the aug-cc-pVTZ). This confirms that the choice of basis set not only can influence the value of the electron population at the particular atom, but can also lead to different ELF topology.
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Nada, R.; Nicholas, J.B.; McCarthy, M.I.; Hess, A.C.
1996-11-15
Silica sodalite is an ideal model system to establish base-line computer requirements of ab initio periodic Hartree-Fock (PHF) calculations of zeolites. In this article, the authors investigate the effect of various basis sets on the structural and electronic properties of bulk silica sodalite. They also study the interaction of He, Ne, and Ar with the sodalite cage. This work shows that basis-set superposition errors (BSSE) in calculations using STO-3G and 6-21G(*) basis sets are as large as the interaction energies, leading to poor confidence in the results. To cure this problem, the authors present high-quality basis sets for si, O, He, Ne, and Ar, optimized for use with PHF methods, and demonstrate that the new basis set greatly reduces BSSE. The theoretical barriers for transfer of the rare gases between sodalite cages are 5.6, 13.2, and 62.1 kcal/mol for He, Ne, and Ar. 27 refs., 6 figs., 8 tabs.
TiCl, TiH and TiH+ Bond Energies, a Test of a Correlation Consistent Ti Basis Set
NASA Technical Reports Server (NTRS)
Bauschlicher, Charles W., Jr.; Arnold, James O. (Technical Monitor)
1999-01-01
Correlation consistent basis sets are developed for Ti atom. The polarization functions are optimized for the average of the 3F and 5F states. One series of correlation consistent basis sets is for 3d and 4s correlation, while the second series includes 3s and 3p correlation as well as 3d and 4s correlation. These basis sets are tested using the Ti 3F-5F separation and the dissociation energies of TiCl X4Phi, TiH X4Phi, and TiH(+) X3Phi. The CCSD(T) complete basis set limit values are determined by extrapolation. The Douglas Kroll approach is used to compute the scalar relativistic effect. Spin-orbit effects are taken from experiment and/or computed at the CASSCF level. The Ti 3F-5F separation is in excellent agreement with experiment, while the TiCl, TiH, and TiH(+) bond energies are in good agreement with experiment. Extrapolation with the valence basis set is consistent with other atoms, while including 3s and 3p correlation appears to make extrapolation.
NASA Astrophysics Data System (ADS)
Lowe, D.; Topping, D. O.; Archer-Nicholls, S.; Darbyshire, E.; Morgan, W.; Liu, D.; Allan, J. D.; Coe, H.; McFiggans, G.
2015-12-01
The burning of forests in the Amazonia region is a globally significant source of carbonaceous aerosol, containing both absorbing and scattering components [1]. In addition biomass burning aerosol (BBA) are also efficient cloud condensation nuclei (CCN), modifying cloud properties and influencing atmospheric circulation and precipitation tendencies [2]. The impacts of BBA are highly dependent on their size distribution and composition. A bottom-up emissions inventory, the Brazilian Biomass Burning Emissions Model (3BEM) [3], utilising satellite products to generate daily fire emission maps is used. Injection of flaming emissions within the atmospheric column is simulated using both a sub-grid plume-rise parameterisation [4], and simpler schemes, within the Weather Research and Forecasting Model with Chemistry (WRF-Chem, v3.4.1) [5]. Aerosol dynamics are simulated using the sectional MOSAIC scheme [6], incorporating a volatility basis set (VBS) treatment of organic aerosol [7]. For this work we have modified the 9-bin VBS to use the biomass burning specific scheme developed by May et al. [8]. The model has been run for September 2012 over South America (at a 25km resolution). We will present model results evaluating the modelled aerosol vertical distribution, size distribution, and composition against measurements taken by the FAAM BAe-146 research aircraft during the SAMBBA campaign. The main focus will be on investigating the factors controlling the vertical gradient of the organic mass to black carbon ratio of the measured aerosol. This work is supported by the Nature Environment Research Council (NERC) as part of the SAMBBA project under grant NE/J010073/1. [1] D. G. Streets et al., 2004, J. Geophys. Res., 109, D24212. [2] M. O. Andreae et al., 2004, Science, 303, 1337-1342. [3] K. Longo et al., 2010, Atmos. Chem. Phys., 10, 5,785-5,795. [4] S. Freitas et al., 2007, Atmos. Chem. Phys., 7, 3,385-3,398. [5] S. Archer-Nicholls et al., 2015, Geosci. Model Dev., 8
Shrivastava, ManishKumar B.; Fast, Jerome D.; Easter, Richard C.; Gustafson, William I.; Zaveri, Rahul A.; Jimenez, Jose L.; Saide, Pablo; Hodzic, Alma
2011-07-13
The Weather Research and Forecasting model coupled with chemistry (WRF-Chem) is modified to include a volatility basis set (VBS) treatment of secondary organic aerosol formation. The VBS approach, coupled with SAPRC-99 gas-phase chemistry mechanism, is used to model gas-particle partitioning and multiple generations of gas-phase oxidation of organic vapors. In addition to the detailed 9-species VBS, a simplified mechanism using 2 volatility species (2-species VBS) is developed and tested for similarity to the 9-species VBS in terms of both mass and oxygen-to-carbon ratios of organic aerosols in the atmosphere. WRF-Chem results are evaluated against field measurements of organic aerosols collected during the MILAGRO 2006 campaign in the vicinity of Mexico City. The simplified 2-species mechanism reduces the computational cost by a factor of 2 as compared to 9-species VBS. Both ground site and aircraft measurements suggest that the 9-species and 2-species VBS predictions of total organic aerosol mass as well as individual organic aerosol components including primary, secondary, and biomass burning are comparable in magnitude. In addition, oxygen-to-carbon ratio predictions from both approaches agree within 25%, providing evidence that the 2-species VBS is well suited to represent the complex evolution of organic aerosols. Model sensitivity to amount of anthropogenic semi-volatile and intermediate volatility (S/IVOC) precursor emissions is also examined by doubling the default emissions. Both the emission cases significantly under-predict primary organic aerosols in the city center and along aircraft flight transects. Secondary organic aerosols are predicted reasonably well along flight tracks surrounding the city, but are consistently over-predicted downwind of the city. Also, oxygen-to-carbon ratio predictions are significantly improved compared to prior studies by adding 15% oxygen mass per generation of oxidation; however, all modeling cases still under
Mazziotti, David A
2007-05-14
Two-electron reduced density matrices (2-RDMs) have recently been directly determined from the solution of the anti-Hermitian contracted Schrodinger equation (ACSE) to obtain 95%-100% of the ground-state correlation energy of atoms and molecules, which significantly improves upon the accuracy of the contracted Schrodinger equation (CSE) [D. A. Mazziotti, Phys. Rev. Lett. 97, 143002 (2006)]. Two subsets of the CSE, the ACSE and the contraction of the CSE onto the one-particle space, known as the 1,3-CSE, have two important properties: (i) dependence upon only the 3-RDM and (ii) inclusion of all second-order terms when the 3-RDM is reconstructed as only a first-order functional of the 2-RDM. The error in the 1,3-CSE has an important role as a stopping criterion in solving the ACSE for the 2-RDM. Using a computationally more efficient implementation of the ACSE, the author treats a variety of molecules, including H2O, NH3, HCN, and HO3-, in larger basis sets such as correlation-consistent polarized double- and triple-zeta. The ground-state energy of neon is also calculated in a polarized quadruple-zeta basis set with extrapolation to the complete basis-set limit, and the equilibrium bond length and harmonic frequency of N2 are computed with comparison to experimental values. The author observes that increasing the basis set enhances the ability of the ACSE to capture correlation effects in ground-state energies and properties. In the triple-zeta basis set, for example, the ACSE yields energies and properties that are closer in accuracy to coupled cluster with single, double, and triple excitations than to coupled cluster with single and double excitations. In all basis sets, the computed 2-RDMs very closely satisfy known N-representability conditions.
Kaprálová-Žďánská, Petra Ruth; Šmydke, Jan; Civiš, Svatopluk
2013-09-14
Recently optimized exponentially tempered Gaussian basis sets [P. R. Kapralova-Zdanska and J. Smydke, J. Chem. Phys. 138, 024105 (2013)] are employed in quantitative simulations of helium absorption cross-sections and two-photon excitation yields of doubly excited resonances. Linearly polarized half-infinite and Gaussian laser pulses at wavelengths 38–58 nm and large intensities up to 100 TW/cm{sup 2} are considered. The emphasis is laid on convergence of the results with respect to the quality of the Gaussian basis sets (typically limited by a number of partial waves, density, and spatial extent of the basis functions) as well as to the quality of the basis set of field-free states (typically limited by the maximum rotational quantum number and maximum excitation of the lower electron). Particular attention is paid to stability of the results with respect to varying complex scaling parameter. Moreover, the study of the dynamics is preceded by a thorough check of helium energies and oscillator strengths as they are obtained with the exponentially tempered Gaussian basis sets, being also compared with yet unpublished emission wavelengths measured in electric discharge experiments.
Teodoro, Tiago Quevedo; Haiduke, Roberto Luiz Andrade
2013-10-15
Accurate relativistic adapted Gaussian basis sets (RAGBSs) for 87 Fr up to 118 Uuo atoms without variational prolapse were developed here with the use of a polynomial version of the Generator Coordinate Dirac-Fock method. Two finite nuclear models have been used, the Gaussian and uniform sphere models. The largest RAGBS error, with respect to numerical Dirac-Fock results, is 15.4 miliHartree for Ununoctium with a basis set size of 33s30p19d14f functions. PMID:23913741
Reuter, Matthew G; Harrison, Robert J
2014-05-01
The thesis of Brandbyge's comment [J. Chem. Phys. 140, 177103 (2014)] is that our operator decoupling condition is immaterial to transport theories, and it appeals to discussions of nonorthogonal basis sets in transport calculations in its arguments. We maintain that the operator condition is to be preferred over the usual matrix conditions and subsequently detail problems in the existing approaches. From this operator perspective, we conclude that nonorthogonal projectors cannot be used and that the projectors must be selected to satisfy the operator decoupling condition. Because these conclusions pertain to operators, the choice of basis set is not germane.
Cybulski, Hubert; Baranowska-Łączkowska, Angelika; Henriksen, Christian; Fernández, Berta
2014-11-01
By evaluating a representative set of CCSD(T) ground state interaction energies for van der Waals dimers formed by aromatic molecules and the argon atom, we test the performance of the polarized basis sets of Sadlej et al. (J. Comput. Chem. 2005, 26, 145; Collect. Czech. Chem. Commun. 1988, 53, 1995) and the augmented polarization-consistent bases of Jensen (J. Chem. Phys. 2002, 117, 9234) in providing accurate intermolecular potentials for the benzene-, naphthalene-, and anthracene-argon complexes. The basis sets are extended by addition of midbond functions. As reference we consider CCSD(T) results obtained with Dunning's bases. For the benzene complex a systematic basis set study resulted in the selection of the (Z)Pol-33211 and the aug-pc-1-33321 bases to obtain the intermolecular potential energy surface. The interaction energy values and the shape of the CCSD(T)/(Z)Pol-33211 calculated potential are very close to the best available CCSD(T)/aug-cc-pVTZ-33211 potential with the former basis set being considerably smaller. The corresponding differences for the CCSD(T)/aug-pc-1-33321 potential are larger. In the case of the naphthalene-argon complex, following a similar study, we selected the (Z)Pol-3322 and aug-pc-1-333221 bases. The potentials show four symmetric absolute minima with energies of -483.2 cm(-1) for the (Z)Pol-3322 and -486.7 cm(-1) for the aug-pc-1-333221 basis set. To further check the performance of the selected basis sets, we evaluate intermolecular bound states of the complexes. The differences between calculated vibrational levels using the CCSD(T)/(Z)Pol-33211 and CCSD(T)/aug-cc-pVTZ-33211 benzene-argon potentials are small and for the lowest energy levels do not exceed 0.70 cm(-1). Such differences are substantially larger for the CCSD(T)/aug-pc-1-33321 calculated potential. For naphthalene-argon, bound state calculations demonstrate that the (Z)Pol-3322 and aug-pc-1-333221 potentials are of similar quality. The results show that these
Molecule intrinsic minimal basis sets. II. Bonding analyses for Si4H6 and Si2 to Si10.
Lu, W C; Wang, C Z; Schmidt, M W; Bytautas, L; Ho, K M; Ruedenberg, K
2004-02-01
The method, introduced in the preceding paper, for recasting molecular self-consistent field (SCF) or density functional theory (DFT) orbitals in terms of intrinsic minimal bases of quasiatomic orbitals, which differ only little from the optimal free-atom minimal-basis orbitals, is used to elucidate the bonding in several silicon clusters. The applications show that the quasiatomic orbitals deviate from the minimal-basis SCF orbitals of the free atoms by only very small deformations and that the latter arise mainly from bonded neighbor atoms. The Mulliken population analysis in terms of the quasiatomic minimal-basis orbitals leads to a quantum mechanical interpretation of small-ring strain in terms of antibonding encroachments of localized molecular-orbitals and identifies the origin of the bond-stretch isomerization in Si4H6. In the virtual SCF/DFT orbital space, the method places the qualitative notion of virtual valence orbitals on a firm basis and provides an unambiguous ab initio identification of the frontier orbitals.
Alam, T.M.
1998-09-01
The influence of changes in the contracted Gaussian basis set used for ab initio calculations of nuclear magnetic resonance (NMR) phosphorous chemical shift anisotropy (CSA) tensors was investigated. The isotropic chemical shitl and chemical shift anisotropy were found to converge with increasing complexity of the basis set at the Hartree-Fock @IF) level. The addition of d polarization function on the phosphorous nucIei was found to have a major impact of the calculated chemical shi~ but diminished with increasing number of polarization fimctions. At least 2 d polarization fimctions are required for accurate calculations of the isotropic phosphorous chemical shift. The introduction of density fictional theory (DFT) techniques through tie use of hybrid B3LYP methods for the calculation of the phosphorous chemical shift tensor resulted in a poorer estimation of the NMR values, even though DFT techniques result in improved energy and force constant calculations. The convergence of the W parametem with increasing basis set complexity was also observed for the DFT calculations, but produced results with consistent large deviations from experiment. The use of a HF 6-31 l++G(242p) basis set represents a good compromise between accuracy of the simulation and the complexity of the calculation for future ab initio calculations of 31P NMR parameters in larger complexes.
Friese, Daniel H.; Törk, Lisa; Hättig, Christof
2014-11-21
We present scaling factors for vibrational frequencies calculated within the harmonic approximation and the correlated wave-function methods coupled cluster singles and doubles model (CC2) and Møller-Plesset perturbation theory (MP2) with and without a spin-component scaling (SCS or spin-opposite scaling (SOS)). Frequency scaling factors and the remaining deviations from the reference data are evaluated for several non-augmented basis sets of the cc-pVXZ family of generally contracted correlation-consistent basis sets as well as for the segmented contracted TZVPP basis. We find that the SCS and SOS variants of CC2 and MP2 lead to a slightly better accuracy for the scaled vibrational frequencies. The determined frequency scaling factors can also be used for vibrational frequencies calculated for excited states through response theory with CC2 and the algebraic diagrammatic construction through second order and their spin-component scaled variants.
Southall, Stacey M; Wong, Poon-Sheng; Odho, Zain; Roe, S Mark; Wilson, Jon R
2009-01-30
The mixed-lineage leukemia protein MLL1 is a transcriptional regulator with an essential role in early development and hematopoiesis. The biological function of MLL1 is mediated by the histone H3K4 methyltransferase activity of the carboxyl-terminal SET domain. We have determined the crystal structure of the MLL1 SET domain in complex with cofactor product AdoHcy and a histone H3 peptide. This structure indicates that, in order to form a well-ordered active site, a highly variable but essential component of the SET domain must be repositioned. To test this idea, we compared the effect of the addition of MLL complex members on methyltransferase activity and show that both RbBP5 and Ash2L but not Wdr5 stimulate activity. Additionally, we have determined the effect of posttranslational modifications on histone H3 residues downstream and upstream from the target lysine and provide a structural explanation for why H3T3 phosphorylation and H3K9 acetylation regulate activity. PMID:19187761
Sure, Rebecca; Brandenburg, Jan Gerit; Grimme, Stefan
2016-04-01
In quantum chemical computations the combination of Hartree-Fock or a density functional theory (DFT) approximation with relatively small atomic orbital basis sets of double-zeta quality is still widely used, for example, in the popular B3LYP/6-31G* approach. In this Review, we critically analyze the two main sources of error in such computations, that is, the basis set superposition error on the one hand and the missing London dispersion interactions on the other. We review various strategies to correct those errors and present exemplary calculations on mainly noncovalently bound systems of widely varying size. Energies and geometries of small dimers, large supramolecular complexes, and molecular crystals are covered. We conclude that it is not justified to rely on fortunate error compensation, as the main inconsistencies can be cured by modern correction schemes which clearly outperform the plain mean-field methods. PMID:27308221
Kobus, J.; Moncrieff, D.; Wilson, S.
2000-12-01
A comparison is made of the accuracy with which the electric moments {mu}, {Theta}, {Omega}, and {Phi} can be calculated by using the finite basis set approach (the algebraic approximation) and finite-difference method in calculations employing the Hartree-Fock model for the ground states of 16 diatomic molecules at their experimental equilibrium geometries. Specifically, the 2{sup n}-pole moments n=1,2,3,4, for the N{sub 2}, CO, BF, CN{sup -}, NO{sup +}, BeF, BO, CN, N{sub 2}{sup +}, AlF, GaF, InF, TlF, MgF, CaF, and SrF molecules are determined using basis sets and grids that have been employed in previous studies of the Hartree-Fock energy.
NASA Astrophysics Data System (ADS)
Baranowska-Łączkowska, Angelika; Fernández, Berta
2015-11-01
Interaction-induced electric dipole moment, polarisability and first hyperpolarisability are investigated in model hydrogen-bonded clusters built of hydrogen fluoride molecules organised in three linear chains parallel to each other. The properties are evaluated within the finite field approach, using the second order Møller-Plesset method, and the LPol-m (m = ds, dl) and the optical rotation prediction (ORP) basis sets. These bases and correlation method are selected after a systematic basis set and correlation method convergence study carried out on the smallest of the complexes and taking properties obtained with Dunning's bases and the coupled cluster singles and doubles (CCSD) and the CCSD including connected triple corrections (CCSD(T)) methods as reference. Results are analysed in terms of many-body and cooperative effects.
NASA Astrophysics Data System (ADS)
Rocca, Dario
2014-05-01
A new ab initio approach is introduced to compute the correlation energy within the adiabatic connection fluctuation dissipation theorem in the random phase approximation. First, an optimally small basis set to represent the response functions is obtained by diagonalizing an approximate dielectric matrix containing the kinetic energy contribution only. Then, the Lanczos algorithm is used to compute the full dynamical dielectric matrix and the correlation energy. The convergence issues with respect to the number of empty states or the dimension of the basis set are avoided and the dynamical effects are easily kept into account. To demonstrate the accuracy and efficiency of this approach the binding curves for three different configurations of the benzene dimer are computed: T-shaped, sandwich, and slipped parallel.
Sure, Rebecca; Brandenburg, Jan Gerit; Grimme, Stefan
2016-04-01
In quantum chemical computations the combination of Hartree-Fock or a density functional theory (DFT) approximation with relatively small atomic orbital basis sets of double-zeta quality is still widely used, for example, in the popular B3LYP/6-31G* approach. In this Review, we critically analyze the two main sources of error in such computations, that is, the basis set superposition error on the one hand and the missing London dispersion interactions on the other. We review various strategies to correct those errors and present exemplary calculations on mainly noncovalently bound systems of widely varying size. Energies and geometries of small dimers, large supramolecular complexes, and molecular crystals are covered. We conclude that it is not justified to rely on fortunate error compensation, as the main inconsistencies can be cured by modern correction schemes which clearly outperform the plain mean-field methods.
Rocca, Dario
2014-05-14
A new ab initio approach is introduced to compute the correlation energy within the adiabatic connection fluctuation dissipation theorem in the random phase approximation. First, an optimally small basis set to represent the response functions is obtained by diagonalizing an approximate dielectric matrix containing the kinetic energy contribution only. Then, the Lanczos algorithm is used to compute the full dynamical dielectric matrix and the correlation energy. The convergence issues with respect to the number of empty states or the dimension of the basis set are avoided and the dynamical effects are easily kept into account. To demonstrate the accuracy and efficiency of this approach the binding curves for three different configurations of the benzene dimer are computed: T-shaped, sandwich, and slipped parallel.
Sure, Rebecca; Brandenburg, Jan Gerit
2015-01-01
Abstract In quantum chemical computations the combination of Hartree–Fock or a density functional theory (DFT) approximation with relatively small atomic orbital basis sets of double‐zeta quality is still widely used, for example, in the popular B3LYP/6‐31G* approach. In this Review, we critically analyze the two main sources of error in such computations, that is, the basis set superposition error on the one hand and the missing London dispersion interactions on the other. We review various strategies to correct those errors and present exemplary calculations on mainly noncovalently bound systems of widely varying size. Energies and geometries of small dimers, large supramolecular complexes, and molecular crystals are covered. We conclude that it is not justified to rely on fortunate error compensation, as the main inconsistencies can be cured by modern correction schemes which clearly outperform the plain mean‐field methods. PMID:27308221
Vastine, Benjamin Alan; Webster, Charles Edwin; Hall, Michael B
2007-11-01
The reaction mechanism for the cycle beginning with the reductive elimination (RE) of methane from κ(3)-TpPt(IV)(CH3)2H (1) (Tp = hydridotris(pyrazolyl)borate) and subsequent oxidative addition (OA) of benzene to form finally κ(3)-TpPt(IV)(Ph)2H (19) was investigated by density functional theory (DFT). Two mechanistic steps are of particular interest, namely the barrier to C-H coupling (barrier 1 - Ba1) and the barrier to methane release (barrier 2 - Ba2). For 31 density functionals, the calculated values for Ba1 and Ba2 were benchmarked against the experimentally reported values of 26 (Ba1) and 35 (Ba2) kcal·mol(-1), respectively. Specifically, the values for Ba1 and Ba2, calculated at the B3LYP/double-ζ plus polarization level of theory, are 24.6 and 34.3 kcal·mol(-1), respectively. Overall, the best performing functional was BPW91 where the mae associated with the calculated values of the two barriers is 0.68 kcal·mol(-1). The calculated B3LYP values of Ba1 ranged between 20 and 26 kcal·mol(-1) for 12 effective core potential basis sets for platinum and 29 all-electron basis sets for the first row elements. Polarization functions for the first row elements were important for accurate values, but the addition of diffuse functions to non-hydrogen (+) and hydrogen atoms (++) had little effect on the calculated values. Basis set saturation was achieved with APNO basis sets utilized for first-row atoms. Bader's "Atoms in Molecules" was used to analyze the electron density of several complexes, and the electron density at the Pt-Nax bond critical point (trans to the active site for C-H coupling) varied over a wider range than any of the other Pt-N bonds.
Orbital-specific Tunability of Many-Body Effects in Bilayer Graphene by Gate Bias and Metal Contact
NASA Astrophysics Data System (ADS)
Fukidome, Hirokazu; Kotsugi, Masato; Nagashio, Kosuke; Sato, Ryo; Ohkochi, Takuo; Itoh, Takashi; Toriumi, Akira; Suemitsu, Maki; Kinoshita, Toyohiko
2014-01-01
Graphene, a 2D crystal bonded by π and σ orbitals, possesses excellent electronic properties that are promising for next-generation optoelectronic device applications. For these a precise understanding of quasiparticle behaviour near the Dirac point (DP) is indispensable because the vanishing density of states (DOS) near the DP enhances many-body effects, such as excitonic effects and the Anderson orthogonality catastrophe (AOC) which occur through the interactions of many conduction electrons with holes. These effects renormalize band dispersion and DOS, and therefore affect device performance. For this reason, we have studied the impact of the excitonic effects and the AOC on graphene device performance by using X-ray absorption spectromicroscopy on an actual graphene transistor in operation. Our work shows that the excitonic effect and the AOC are tunable by gate bias or metal contacts, both of which alter the Fermi energy, and are orbital-specific.
Cheng, Lan Stanton, John F.; Gauss, Jürgen
2015-06-14
A systematic relativistic coupled-cluster study is reported on the harmonic vibrational frequencies of the O{sub h}, C{sub 3v}, and C{sub 2v} conformers of XeF{sub 6}, with scalar-relativistic effects efficiently treated using the spin-free exact two-component theory in its one-electron variant (SFX2C-1e). Atomic natural orbital type basis sets recontracted for the SFX2C-1e scheme have been shown to provide rapid basis-set convergence for the vibrational frequencies. SFX2C-1e as well as complementary pseudopotential based computations consistently predicts that both O{sub h} and C{sub 3v} structures are local minima on the potential energy surface, while the C{sub 2v} structure is a transition state. Qualitative disagreement between the present results for the O{sub h} structure and those from CCSD(T)-F12b calculations [Peterson et al., J. Phys. Chem. A 116, 9777 (2012)], which yielded a triply degenerate imaginary frequency for the O{sub h} structure, is attributed here to the high sensitivity of the computed harmonic frequencies of the t{sub 1u} bending modes to the basis-set effects of triples contributions.
NASA Astrophysics Data System (ADS)
Kobus, J.; Moncrieff, D.; Wilson, S.
2001-12-01
A comparison is made of the accuracy by which the electric dipole polarizability αzz and hyperpolarizability βzzz can be calculated by using the finite basis set approach (the algebraic approximation) and finite difference method in calculations employing the Hartree-Fock model. The numerical and algebraic methods were tested on the ground states of H2, LiH, BH and FH molecules at their respective experimental equilibrium geometries. For the FH molecule at its experimental equilibrium geometry, a sequence of distributed universal even-tempered basis sets have been used to explore the convergence pattern of the total energy, dipole moment and polarizabilities. The comparison of finite difference and finite basis set methods is extended to geometries for which the nuclear separation, RFH, lies in the range 1.5-2.2 b. The methods give consistent results to within 1% or better. In the case of the FH molecule the dependence of truncation errors of the total energy, dipole moment and polarizabilities on the geometry have been studied and are shown to be negligible.
Srinivasan, Sriram Goverapet; Goldman, Nir; Tamblyn, Isaac; Hamel, Sebastien; Gaus, Michael
2014-07-24
We present a new DFTB-p3b density functional tight binding model for hydrogen at extremely high pressures and temperatures, which includes a polarizable basis set (p) and a three-body environmentally dependent repulsive potential (3b). We find that use of an extended basis set is necessary under dissociated liquid conditions to account for the substantial p-orbital character of the electronic states around the Fermi energy. The repulsive energy is determined through comparison to cold curve pressures computed from density functional theory (DFT) for the hexagonal close-packed solid, as well as pressures from thermally equilibrated DFT-MD simulations of the liquid phase. In particular, we observe improved agreement in our DFTB-p3b model with previous theoretical and experimental results for the shock Hugoniot of hydrogen up to 100 GPa and 25000 K, compared to a standard DFTB model using pairwise interactions and an s-orbital basis set, only. The DFTB-p3b approach discussed here provides a general method to extend the DFTB method for a wide variety of materials over a significantly larger range of thermodynamic conditions than previously possible. PMID:24960065
Chitwood, Daniel H.; Kumar, Ravi; Headland, Lauren R.; Ranjan, Aashish; Covington, Michael F.; Ichihashi, Yasunori; Fulop, Daniel; Jiménez-Gómez, José M.; Peng, Jie; Maloof, Julin N.; Sinha, Neelima R.
2013-01-01
Introgression lines (ILs), in which genetic material from wild tomato species is introgressed into a domesticated background, have been used extensively in tomato (Solanum lycopersicum) improvement. Here, we genotype an IL population derived from the wild desert tomato Solanum pennellii at ultrahigh density, providing the exact gene content harbored by each line. To take advantage of this information, we determine IL phenotypes for a suite of vegetative traits, ranging from leaf complexity, shape, and size to cellular traits, such as stomatal density and epidermal cell phenotypes. Elliptical Fourier descriptors on leaflet outlines provide a global analysis of highly heritable, intricate aspects of leaf morphology. We also demonstrate constraints between leaflet size and leaf complexity, pavement cell size, and stomatal density and show independent segregation of traits previously assumed to be genetically coregulated. Meta-analysis of previously measured traits in the ILs shows an unexpected relationship between leaf morphology and fruit sugar levels, which RNA-Seq data suggest may be attributable to genetically coregulated changes in fruit morphology or the impact of leaf shape on photosynthesis. Together, our results both improve upon the utility of an important genetic resource and attest to a complex, genetic basis for differences in leaf morphology between natural populations. PMID:23872539
Höfener, Sebastian; Bischoff, Florian A; Glöss, Andreas; Klopper, Wim
2008-06-21
In the recent years, Slater-type geminals (STGs) have been used with great success to expand the first-order wave function in an explicitly-correlated perturbation theory. The present work reports on this theory's implementation in the framework of the Turbomole suite of programs. A formalism is presented for evaluating all of the necessary molecular two-electron integrals by means of the Obara-Saika recurrence relations, which can be applied when the STG is expressed as a linear combination of a small number (n) of Gaussians (STG-nG geminal basis). In the Turbomole implementation of the theory, density fitting is employed and a complementary auxiliary basis set (CABS) is used for the resolution-of-the-identity (RI) approximation of explicitly-correlated theory. By virtue of this RI approximation, the calculation of molecular three- and four-electron integrals is avoided. An approximation is invoked to avoid the two-electron integrals over the commutator between the operators of kinetic energy and the STG. This approximation consists of computing commutators between matrices in place of operators. Integrals over commutators between operators would have occurred if the theory had been formulated and implemented as proposed originally. The new implementation in Turbomole was tested by performing a series of calculations on rotational conformers of the alkanols n-propanol through n-pentanol. Basis-set requirements concerning the orbital basis, the auxiliary basis set for density fitting and the CABS were investigated. Furthermore, various (constrained) optimizations of the amplitudes of the explicitly-correlated double excitations were studied. These amplitudes can be optimized in orbital-variant and orbital-invariant manners, or they can be kept fixed at the values governed by the rational generator approach, that is, by the electron cusp conditions. Electron-correlation effects beyond the level of second-order perturbation theory were accounted for by conventional
Kruse, Holger; Grimme, Stefan
2012-04-21
A semi-empirical counterpoise-type correction for basis set superposition error (BSSE) in molecular systems is presented. An atom pair-wise potential corrects for the inter- and intra-molecular BSSE in supermolecular Hartree-Fock (HF) or density functional theory (DFT) calculations. This geometrical counterpoise (gCP) denoted scheme depends only on the molecular geometry, i.e., no input from the electronic wave-function is required and hence is applicable to molecules with ten thousands of atoms. The four necessary parameters have been determined by a fit to standard Boys and Bernadi counterpoise corrections for Hobza's S66×8 set of non-covalently bound complexes (528 data points). The method's target are small basis sets (e.g., minimal, split-valence, 6-31G*), but reliable results are also obtained for larger triple-ζ sets. The intermolecular BSSE is calculated by gCP within a typical error of 10%-30% that proves sufficient in many practical applications. The approach is suggested as a quantitative correction in production work and can also be routinely applied to estimate the magnitude of the BSSE beforehand. The applicability for biomolecules as the primary target is tested for the crambin protein, where gCP removes intramolecular BSSE effectively and yields conformational energies comparable to def2-TZVP basis results. Good mutual agreement is also found with Jensen's ACP(4) scheme, estimating the intramolecular BSSE in the phenylalanine-glycine-phenylalanine tripeptide, for which also a relaxed rotational energy profile is presented. A variety of minimal and double-ζ basis sets combined with gCP and the dispersion corrections DFT-D3 and DFT-NL are successfully benchmarked on the S22 and S66 sets of non-covalent interactions. Outstanding performance with a mean absolute deviation (MAD) of 0.51 kcal/mol (0.38 kcal/mol after D3-refit) is obtained at the gCP-corrected HF-D3/(minimal basis) level for the S66 benchmark. The gCP-corrected B3LYP-D3/6-31G* model
Legler, C R; Brown, N R; Dunbar, R A; Harness, M D; Nguyen, K; Oyewole, O; Collier, W B
2015-06-15
The Scaled Quantum Mechanical (SQM) method of scaling calculated force constants to predict theoretically calculated vibrational frequencies is expanded to include a broad array of polarized and augmented basis sets based on the split valence 6-31G and 6-311G basis sets with the B3LYP density functional. Pulay's original choice of a single polarized 6-31G(d) basis coupled with a B3LYP functional remains the most computationally economical choice for scaled frequency calculations. But it can be improved upon with additional polarization functions and added diffuse functions for complex molecular systems. The new scale factors for the B3LYP density functional and the 6-31G, 6-31G(d), 6-31G(d,p), 6-31G+(d,p), 6-31G++(d,p), 6-311G, 6-311G(d), 6-311G(d,p), 6-311G+(d,p), 6-311G++(d,p), 6-311G(2d,p), 6-311G++(2d,p), 6-311G++(df,p) basis sets are shown. The double d polarized models did not perform as well and the source of the decreased accuracy was investigated. An alternate system of generating internal coordinates that uses the out-of plane wagging coordinate whenever it is possible; makes vibrational assignments via potential energy distributions more meaningful. Automated software to produce SQM scaled vibrational calculations from different molecular orbital packages is presented. PMID:25766474
NASA Astrophysics Data System (ADS)
Legler, C. R.; Brown, N. R.; Dunbar, R. A.; Harness, M. D.; Nguyen, K.; Oyewole, O.; Collier, W. B.
2015-06-01
The Scaled Quantum Mechanical (SQM) method of scaling calculated force constants to predict theoretically calculated vibrational frequencies is expanded to include a broad array of polarized and augmented basis sets based on the split valence 6-31G and 6-311G basis sets with the B3LYP density functional. Pulay's original choice of a single polarized 6-31G(d) basis coupled with a B3LYP functional remains the most computationally economical choice for scaled frequency calculations. But it can be improved upon with additional polarization functions and added diffuse functions for complex molecular systems. The new scale factors for the B3LYP density functional and the 6-31G, 6-31G(d), 6-31G(d,p), 6-31G+(d,p), 6-31G++(d,p), 6-311G, 6-311G(d), 6-311G(d,p), 6-311G+(d,p), 6-311G++(d,p), 6-311G(2d,p), 6-311G++(2d,p), 6-311G++(df,p) basis sets are shown. The double d polarized models did not perform as well and the source of the decreased accuracy was investigated. An alternate system of generating internal coordinates that uses the out-of plane wagging coordinate whenever it is possible; makes vibrational assignments via potential energy distributions more meaningful. Automated software to produce SQM scaled vibrational calculations from different molecular orbital packages is presented.
Varandas, A. J. C.; Pansini, F. N. N.
2014-12-14
A method previously suggested to calculate the correlation energy at the complete one-electron basis set limit by reassignment of the basis hierarchical numbers and use of the unified singlet- and triplet-pair extrapolation scheme is applied to a test set of 106 systems, some with up to 48 electrons. The approach is utilized to obtain extrapolated correlation energies from raw values calculated with second-order Møller-Plesset perturbation theory and the coupled-cluster singles and doubles excitations method, some of the latter also with the perturbative triples corrections. The calculated correlation energies have also been used to predict atomization energies within an additive scheme. Good agreement is obtained with the best available estimates even when the (d, t) pair of hierarchical numbers is utilized to perform the extrapolations. This conceivably justifies that there is no strong reason to exclude double-zeta energies in extrapolations, especially if the basis is calibrated to comply with the theoretical model.
Haiduke, Roberto L A; De Macedo, Luiz G M; Da Silva, Albérico B F
2005-07-15
An accurate relativistic universal Gaussian basis set (RUGBS) from H through No without variational prolapse has been developed by employing the Generator Coordinate Dirac-Fock (GCDF) method. The behavior of our RUGBS was tested with two nuclear models: (1) the finite nucleus of uniform proton-charge distribution, and (2) the finite nucleus with a Gaussian proton-charge distribution. The largest error between our Dirac-Fock-Coulomb total energy values and those calculated numerically is 8.8 mHartree for the No atom.
NASA Astrophysics Data System (ADS)
Rangel, T.; Caliste, D.; Genovese, L.; Torrent, M.
2016-11-01
We present a Projector Augmented-Wave (PAW) method based on a wavelet basis set. We implemented our wavelet-PAW method as a PAW library in the ABINIT package [http://www.abinit.org] and into BigDFT [http://www.bigdft.org]. We test our implementation in prototypical systems to illustrate the potential usage of our code. By using the wavelet-PAW method, we can simulate charged and special boundary condition systems with frozen-core all-electron precision. Furthermore, our work paves the way to large-scale and potentially order- N simulations within a PAW method.
Haiduke, Roberto L A; De Macedo, Luiz G M; Da Silva, Albérico B F
2005-07-15
An accurate relativistic universal Gaussian basis set (RUGBS) from H through No without variational prolapse has been developed by employing the Generator Coordinate Dirac-Fock (GCDF) method. The behavior of our RUGBS was tested with two nuclear models: (1) the finite nucleus of uniform proton-charge distribution, and (2) the finite nucleus with a Gaussian proton-charge distribution. The largest error between our Dirac-Fock-Coulomb total energy values and those calculated numerically is 8.8 mHartree for the No atom. PMID:15841472
Zen, Andrea; Luo, Ye; Sorella, Sandro; Guidoni, Leonardo
2014-01-01
Quantum Monte Carlo methods are accurate and promising many body techniques for electronic structure calculations which, in the last years, are encountering a growing interest thanks to their favorable scaling with the system size and their efficient parallelization, particularly suited for the modern high performance computing facilities. The ansatz of the wave function and its variational flexibility are crucial points for both the accurate description of molecular properties and the capabilities of the method to tackle large systems. In this paper, we extensively analyze, using different variational ansatzes, several properties of the water molecule, namely, the total energy, the dipole and quadrupole momenta, the ionization and atomization energies, the equilibrium configuration, and the harmonic and fundamental frequencies of vibration. The investigation mainly focuses on variational Monte Carlo calculations, although several lattice regularized diffusion Monte Carlo calculations are also reported. Through a systematic study, we provide a useful guide to the choice of the wave function, the pseudopotential, and the basis set for QMC calculations. We also introduce a new method for the computation of forces with finite variance on open systems and a new strategy for the definition of the atomic orbitals involved in the Jastrow-Antisymmetrised Geminal power wave function, in order to drastically reduce the number of variational parameters. This scheme significantly improves the efficiency of QMC energy minimization in case of large basis sets. PMID:24526929
NASA Astrophysics Data System (ADS)
Evarestov, R. A.; Panin, A. I.; Bandura, A. V.; Losev, M. V.
2008-06-01
The results of LCAO DFT calculations of lattice parameters, cohesive energy and bulk modulus of the crystalline uranium nitrides UN, U2N3 and UN2 are presented and discussed. The LCAO computer codes Gaussian03 and Crystal06 are applied. The calculations are made with the uranium atom relativistic effective small core potential by Stuttgart-Cologne group (60 electrons in the core). The calculations include the U atom basis set optimization. Powell, Hooke-Jeeves, conjugated gradient and Box methods are implemented in the author's optimization package, being external to the codes for molecular and periodic calculations. The basis set optimization in LCAO calculations improves the agreement of the lattice parameter and bulk modulus of UN crystal with the experimental data, the change of the cohesive energy due to the optimization is small. The mixed metallic-covalent chemical bonding is found both in LCAO calculations of UN and U2N3 crystals; UN2 crystal has the semiconducting nature.
Zhao, Bin; Wang, Shuxiao; Donahue, Neil M; Chuang, Wayne; Hildebrandt Ruiz, Lea; Ng, Nga L; Wang, Yangjun; Hao, Jiming
2015-02-17
We evaluate the one-dimensional volatility basis set (1D-VBS) and two-dimensional volatility basis set (2D-VBS) in simulating the aging of SOA derived from toluene and α-pinene against smog-chamber experiments. If we simulate the first-generation products with empirical chamber fits and the subsequent aging chemistry with a 1D-VBS or a 2D-VBS, the models mostly overestimate the SOA concentrations in the toluene oxidation experiments. This is because the empirical chamber fits include both first-generation oxidation and aging; simulating aging in addition to this results in double counting of the initial aging effects. If the first-generation oxidation is treated explicitly, the base-case 2D-VBS underestimates the SOA concentrations and O:C increase of the toluene oxidation experiments; it generally underestimates the SOA concentrations and overestimates the O:C increase of the α-pinene experiments. With the first-generation oxidation treated explicitly, we could modify the 2D-VBS configuration individually for toluene and α-pinene to achieve good model-measurement agreement. However, we are unable to simulate the oxidation of both toluene and α-pinene with the same 2D-VBS configuration. We suggest that future models should implement parallel layers for anthropogenic (aromatic) and biogenic precursors, and that more modeling studies and laboratory research be done to optimize the "best-guess" parameters for each layer.
NASA Astrophysics Data System (ADS)
Balabanov, Nikolai B.; Peterson, Kirk A.
2006-08-01
Recently developed correlation consistent basis sets for the first row transition metal elements Sc-Zn have been utilized to determine complete basis set (CBS) scalar relativistic electron affinities, ionization potentials, and 4s23dn -2-4s1dn -1 electronic excitation energies with single reference coupled cluster methods [CCSD(T), CCSDT, and CCSDTQ] and multireference configuration interaction with three reference spaces: 3d4s, 3d4s4p, and 3d4s4p3d'. The theoretical values calculated with the highest order coupled cluster techniques at the CBS limit, including extrapolations to full configuration interaction, are well within 1kcal/mol of the corresponding experimental data. For the early transition metal elements (Sc-Mn) the internally contracted multireference averaged coupled pair functional method yielded excellent agreement with experiment; however, the atomic properties for the late transition metals (Mn-Zn) proved to be much more difficult to describe with this level of theory, even with the largest reference function of the present work.
NASA Astrophysics Data System (ADS)
Dixit, Anant; Ángyán, János G.; Rocca, Dario
2016-09-01
A new formalism was recently proposed to improve random phase approximation (RPA) correlation energies by including approximate exchange effects [B. Mussard et al., J. Chem. Theory Comput. 12, 2191 (2016)]. Within this framework, by keeping only the electron-hole contributions to the exchange kernel, two approximations can be obtained: An adiabatic connection analog of the second order screened exchange (AC-SOSEX) and an approximate electron-hole time-dependent Hartree-Fock (eh-TDHF). Here we show how this formalism is suitable for an efficient implementation within the plane-wave basis set. The response functions involved in the AC-SOSEX and eh-TDHF equations can indeed be compactly represented by an auxiliary basis set obtained from the diagonalization of an approximate dielectric matrix. Additionally, the explicit calculation of unoccupied states can be avoided by using density functional perturbation theory techniques and the matrix elements of dynamical response functions can be efficiently computed by applying the Lanczos algorithm. As shown by several applications to reaction energies and weakly bound dimers, the inclusion of the electron-hole kernel significantly improves the accuracy of ground-state correlation energies with respect to RPA and semi-local functionals.
Dixit, Anant; Ángyán, János G; Rocca, Dario
2016-09-14
A new formalism was recently proposed to improve random phase approximation (RPA) correlation energies by including approximate exchange effects [B. Mussard et al., J. Chem. Theory Comput. 12, 2191 (2016)]. Within this framework, by keeping only the electron-hole contributions to the exchange kernel, two approximations can be obtained: An adiabatic connection analog of the second order screened exchange (AC-SOSEX) and an approximate electron-hole time-dependent Hartree-Fock (eh-TDHF). Here we show how this formalism is suitable for an efficient implementation within the plane-wave basis set. The response functions involved in the AC-SOSEX and eh-TDHF equations can indeed be compactly represented by an auxiliary basis set obtained from the diagonalization of an approximate dielectric matrix. Additionally, the explicit calculation of unoccupied states can be avoided by using density functional perturbation theory techniques and the matrix elements of dynamical response functions can be efficiently computed by applying the Lanczos algorithm. As shown by several applications to reaction energies and weakly bound dimers, the inclusion of the electron-hole kernel significantly improves the accuracy of ground-state correlation energies with respect to RPA and semi-local functionals. PMID:27634249
Zen, Andrea; Luo, Ye; Sorella, Sandro; Guidoni, Leonardo
2013-10-01
Quantum Monte Carlo methods are accurate and promising many body techniques for electronic structure calculations which, in the last years, are encountering a growing interest thanks to their favorable scaling with the system size and their efficient parallelization, particularly suited for the modern high performance computing facilities. The ansatz of the wave function and its variational flexibility are crucial points for both the accurate description of molecular properties and the capabilities of the method to tackle large systems. In this paper, we extensively analyze, using different variational ansatzes, several properties of the water molecule, namely, the total energy, the dipole and quadrupole momenta, the ionization and atomization energies, the equilibrium configuration, and the harmonic and fundamental frequencies of vibration. The investigation mainly focuses on variational Monte Carlo calculations, although several lattice regularized diffusion Monte Carlo calculations are also reported. Through a systematic study, we provide a useful guide to the choice of the wave function, the pseudopotential, and the basis set for QMC calculations. We also introduce a new method for the computation of forces with finite variance on open systems and a new strategy for the definition of the atomic orbitals involved in the Jastrow-Antisymmetrised Geminal power wave function, in order to drastically reduce the number of variational parameters. This scheme significantly improves the efficiency of QMC energy minimization in case of large basis sets. PMID:24526929
Zhao, Bin; Wang, Shuxiao; Donahue, Neil M; Chuang, Wayne; Hildebrandt Ruiz, Lea; Ng, Nga L; Wang, Yangjun; Hao, Jiming
2015-02-17
We evaluate the one-dimensional volatility basis set (1D-VBS) and two-dimensional volatility basis set (2D-VBS) in simulating the aging of SOA derived from toluene and α-pinene against smog-chamber experiments. If we simulate the first-generation products with empirical chamber fits and the subsequent aging chemistry with a 1D-VBS or a 2D-VBS, the models mostly overestimate the SOA concentrations in the toluene oxidation experiments. This is because the empirical chamber fits include both first-generation oxidation and aging; simulating aging in addition to this results in double counting of the initial aging effects. If the first-generation oxidation is treated explicitly, the base-case 2D-VBS underestimates the SOA concentrations and O:C increase of the toluene oxidation experiments; it generally underestimates the SOA concentrations and overestimates the O:C increase of the α-pinene experiments. With the first-generation oxidation treated explicitly, we could modify the 2D-VBS configuration individually for toluene and α-pinene to achieve good model-measurement agreement. However, we are unable to simulate the oxidation of both toluene and α-pinene with the same 2D-VBS configuration. We suggest that future models should implement parallel layers for anthropogenic (aromatic) and biogenic precursors, and that more modeling studies and laboratory research be done to optimize the "best-guess" parameters for each layer. PMID:25581402
NASA Astrophysics Data System (ADS)
Löptien, U.; Dietze, H.
2014-12-01
The Baltic Sea is a seasonally ice-covered, marginal sea in central northern Europe. It is an essential waterway connecting highly industrialised countries. Because ship traffic is intermittently hindered by sea ice, the local weather services have been monitoring sea ice conditions for decades. In the present study we revisit a historical monitoring data set, covering the winters 1960/1961 to 1978/1979. This data set, dubbed Data Bank for Baltic Sea Ice and Sea Surface Temperatures (BASIS) ice, is based on hand-drawn maps that were collected and then digitised in 1981 in a joint project of the Finnish Institute of Marine Research (today the Finnish Meteorological Institute (FMI)) and the Swedish Meteorological and Hydrological Institute (SMHI). BASIS ice was designed for storage on punch cards and all ice information is encoded by five digits. This makes the data hard to access. Here we present a post-processed product based on the original five-digit code. Specifically, we convert to standard ice quantities (including information on ice types), which we distribute in the current and free Network Common Data Format (NetCDF). Our post-processed data set will help to assess numerical ice models and provide easy-to-access unique historical reference material for sea ice in the Baltic Sea. In addition we provide statistics showcasing the data quality. The website http://www.baltic-ocean.org hosts the post-processed data and the conversion code. The data are also archived at the Data Publisher for Earth & Environmental Science, PANGAEA (doi:10.1594/PANGAEA.832353).
NASA Astrophysics Data System (ADS)
Löptien, U.; Dietze, H.
2014-06-01
The Baltic Sea is a seasonally ice-covered, marginal sea, situated in central northern Europe. It is an essential waterway connecting highly industrialised countries. Because ship traffic is intermittently hindered by sea ice, the local weather services have been monitoring sea ice conditions for decades. In the present study we revisit a historical monitoring data set, covering the winters 1960/1961. This data set, dubbed Data Bank for Baltic Sea Ice and Sea Surface Temperatures (BASIS) ice, is based on hand-drawn maps that were collected and then digitised 1981 in a joint project of the Finnish Institute of Marine Research (today Finish Meteorological Institute (FMI)) and the Swedish Meteorological and Hydrological Institute (SMHI). BASIS ice was designed for storage on punch cards and all ice information is encoded by five digits. This makes the data hard to access. Here we present a post-processed product based on the original five-digit code. Specifically, we convert to standard ice quantities (including information on ice types), which we distribute in the current and free Network Common Data Format (NetCDF). Our post-processed data set will help to assess numerical ice models and provide easy-to-access unique historical reference material for sea ice in the Baltic Sea. In addition we provide statistics showcasing the data quality. The website www.baltic-ocean.org hosts the post-prossed data and the conversion code. The data are also archived at the Data Publisher for Earth & Environmental Science PANGEA (doi:10.1594/PANGEA.832353).
Microstructure Modeling in Integrated Computational Materials Engineering (ICME) Settings: Can HDF5 Provide the Basis for an Emerging Standard for Describing Microstructures?
NASA Astrophysics Data System (ADS)
Schmitz, G. J.
2016-01-01
The importance of microstructure simulation in integrated computational materials engineering settings in relation to the added value provided for macroscopic process simulation, as well as the contribution this kind of simulation can make in predicting material properties, are discussed. The roles of microstructure simulation in integrating scales ranging from component/process scales down to atomistic scales, and also in integrating experimental and virtual worlds, are highlighted. The hierarchical data format (HDF5) as a basis for enhancing the interoperability of the heterogeneous range of simulation tools and experimental datasets in the area of computational materials engineering is discussed. Several ongoing developments indicate that HDF5 might evolve into a de facto standard for digital microstructure representation of all length scales.
Peverati, Roberto; Baldridge, Kim K
2009-10-13
The implementation, optimization, and performance of DFT-D, including the effects of solvation, has been tested on applications of polar processes in solution, where dispersion and hydrogen bonding is known to be involved. Solvent effects are included using our ab initio continuum solvation strategy, COSab, a conductor-like continuum solvation model, modified for ab initio in the quantum chemistry program GAMESS. Structure and properties are investigated across various functionals to evaluate their ability to properly model dispersion and solvation effects. The commonly used S22 set with accurate interaction energies of organic complexes has been used for parametrization studies of dispersion parameters and relevant solvation parameters. Dunning's correlation consistent basis sets, cc-pVnZ (n = D, T), are used in the optimization, together with the Grimme B97-D exchange-correlation functional. Both water (ε = 78.4) and ether (ε = 4.33) environments are considered. Optimized semiempirical dispersion correction parameters and solvent extent radii are proposed for several functionals. We find that special parametrization of the semiempirical dispersion correction when used together in the DFT-D/COSab approach is not necessary. The global performance is quite acceptable in terms of chemical accuracy and suggests that this approach is a reliable as well as economical method for evaluation of solvent effects in systems with dispersive interactions. The resulting theory is applied to a group of push-pull pyrrole systems to illustrate the effects of donor/acceptor and solvation on their conformational and energetic properties.
Echenique, Pablo; Alonso, José Luis
2008-07-15
We present an exhaustive study of more than 250 ab initio potential energy surfaces (PESs) of the model dipeptide HCO-L-Ala-NH(2). The model chemistries (MCs) investigated are constructed as homo- and heterolevels involving possibly different RHF and MP2 calculations for the geometry and the energy. The basis sets used belong to a sample of 39 representants from Pople's split-valence families, ranging from the small 3-21G to the large 6-311++G(2df,2pd). The reference PES to which the rest are compared is the MP2/6-311++G(2df,2pd) homolevel, which, as far as we are aware, is the most accurate PES in the literature. All data sets have been analyzed according to a general framework, which can be extended to other complex problems and which captures the nearness concept in the space of MCs. The great number of MCs evaluated has allowed us to significantly explore this space and show that the correlation between accuracy and computational cost of the methods is imperfect, thus justifying a systematic search for the combination of features in a MC that is optimal to deal with peptides. Regarding the particular MCs studied, the most important conclusion is that the potentially very cost-saving heterolevel approximation is a very efficient one to describe the whole PES of HCO-L-Ala-NH(2). Finally, we show that, although RHF may be used to calculate the geometry if a MP2 single-point energy calculation follows, pure RHF//RHF homolevels are not recommendable for this problem.
Goldfeld, Dahlia A; Bochevarov, Arteum D; Friesner, Richard A
2008-12-01
This paper is a logical continuation of the 22 parameter, localized orbital correction (LOC) methodology that we developed in previous papers [R. A. Friesner et al., J. Chem. Phys. 125, 124107 (2006); E. H. Knoll and R. A. Friesner, J. Phys. Chem. B 110, 18787 (2006).] This methodology allows one to redress systematic density functional theory (DFT) errors, rooted in DFT's inherent inability to accurately describe nondynamical correlation. Variants of the LOC scheme, in conjunction with B3LYP (denoted as B3LYP-LOC), were previously applied to enthalpies of formation, ionization potentials, and electron affinities and showed impressive reduction in the errors. In this paper, we demonstrate for the first time that the B3LYP-LOC scheme is robust across different basis sets [6-31G( *), 6-311++G(3df,3pd), cc-pVTZ, and aug-cc-pVTZ] and reaction types (atomization reactions and molecular reactions). For example, for a test set of 70 molecular reactions, the LOC scheme reduces their mean unsigned error from 4.7 kcal/mol [obtained with B3LYP/6-311++G(3df,3pd)] to 0.8 kcal/mol. We also verified whether the LOC methodology would be equally successful if applied to the promising M05-2X functional. We conclude that although M05-2X produces better reaction enthalpies than B3LYP, the LOC scheme does not combine nearly as successfully with M05-2X than with B3LYP. A brief analysis of another functional, M06-2X, reveals that it is more accurate than M05-2X but its combination with LOC still cannot compete in accuracy with B3LYP-LOC. Indeed, B3LYP-LOC remains the best method of computing reaction enthalpies.
Tong, Xin; Cerný, Jirí; Müller-Dethlefs, Klaus; Dessent, Caroline E H
2008-07-01
Two conformational isomers of the aromatic hydrocarbon n-butylbenzene have been studied using two-color MATI (mass analyzed threshold ionization) spectroscopy to explore the effect of conformation on ionization dynamics. Cationic states of g auche-conformer III and anti- conformers IV were selectively produced by two-color excitation via the respective S 1 origins. Adiabatic ionization potentials of the gauche- and anti-conformations were determined to be 70146 and 69872 +/- 5 cm (-1) respectively. Spectral features and vibrational modes are interpreted with the aid of MP2/cc-pVDZ ab initio calculations, and ionization-induced changes in the molecular conformations are discussed. Complete basis set (CBS) ab initio studies at MP2 level reveal reliable energetics for all four n-butylbenzene conformers observed in earlier two-color REMPI (resonance enhanced multiphoton ionization) spectra. For the S 0 state, the energies of conformer III, IV and V are above conformer I by 130, 289, 73 cm (-1), respectively. Furthermore, the combination of the CBS calculations with the measured REMPI, MATI spectra allowed the determination of the energetics of all four conformers in the S 1 and D 0 states.
Tong, Xin; Cerný, Jirí; Müller-Dethlefs, Klaus; Dessent, Caroline E H
2008-07-01
Two conformational isomers of the aromatic hydrocarbon n-butylbenzene have been studied using two-color MATI (mass analyzed threshold ionization) spectroscopy to explore the effect of conformation on ionization dynamics. Cationic states of g auche-conformer III and anti- conformers IV were selectively produced by two-color excitation via the respective S 1 origins. Adiabatic ionization potentials of the gauche- and anti-conformations were determined to be 70146 and 69872 +/- 5 cm (-1) respectively. Spectral features and vibrational modes are interpreted with the aid of MP2/cc-pVDZ ab initio calculations, and ionization-induced changes in the molecular conformations are discussed. Complete basis set (CBS) ab initio studies at MP2 level reveal reliable energetics for all four n-butylbenzene conformers observed in earlier two-color REMPI (resonance enhanced multiphoton ionization) spectra. For the S 0 state, the energies of conformer III, IV and V are above conformer I by 130, 289, 73 cm (-1), respectively. Furthermore, the combination of the CBS calculations with the measured REMPI, MATI spectra allowed the determination of the energetics of all four conformers in the S 1 and D 0 states. PMID:18533642
Rodriguez-Bautista, Mariano; Díaz-García, Cecilia; Navarrete-López, Alejandra M; Vargas, Rubicelia; Garza, Jorge
2015-07-21
In this report, we use a new basis set for Hartree-Fock calculations related to many-electron atoms confined by soft walls. One- and two-electron integrals were programmed in a code based in parallel programming techniques. The results obtained with this proposal for hydrogen and helium atoms were contrasted with other proposals to study just one and two electron confined atoms, where we have reproduced or improved the results previously reported. Usually, an atom enclosed by hard walls has been used as a model to study confinement effects on orbital energies, the main conclusion reached by this model is that orbital energies always go up when the confinement radius is reduced. However, such an observation is not necessarily valid for atoms confined by penetrable walls. The main reason behind this result is that for atoms with large polarizability, like beryllium or potassium, external orbitals are delocalized when the confinement is imposed and consequently, the internal orbitals behave as if they were in an ionized atom. Naturally, the shell structure of these atoms is modified drastically when they are confined. The delocalization was an argument proposed for atoms confined by hard walls, but it was never verified. In this work, the confinement imposed by soft walls allows to analyze the delocalization concept in many-electron atoms.
Rodriguez-Bautista, Mariano; Díaz-García, Cecilia; Navarrete-López, Alejandra M.; Vargas, Rubicelia; Garza, Jorge
2015-07-21
In this report, we use a new basis set for Hartree-Fock calculations related to many-electron atoms confined by soft walls. One- and two-electron integrals were programmed in a code based in parallel programming techniques. The results obtained with this proposal for hydrogen and helium atoms were contrasted with other proposals to study just one and two electron confined atoms, where we have reproduced or improved the results previously reported. Usually, an atom enclosed by hard walls has been used as a model to study confinement effects on orbital energies, the main conclusion reached by this model is that orbital energies always go up when the confinement radius is reduced. However, such an observation is not necessarily valid for atoms confined by penetrable walls. The main reason behind this result is that for atoms with large polarizability, like beryllium or potassium, external orbitals are delocalized when the confinement is imposed and consequently, the internal orbitals behave as if they were in an ionized atom. Naturally, the shell structure of these atoms is modified drastically when they are confined. The delocalization was an argument proposed for atoms confined by hard walls, but it was never verified. In this work, the confinement imposed by soft walls allows to analyze the delocalization concept in many-electron atoms.
Goerigk, Lars; Collyer, Charles A; Reimers, Jeffrey R
2014-12-18
We demonstrate the importance of properly accounting for London dispersion and basis-set-superposition error (BSSE) in quantum-chemical optimizations of protein structures, factors that are often still neglected in contemporary applications. We optimize a portion of an ensemble of conformationally flexible lysozyme structures obtained from highly accurate X-ray crystallography data that serve as a reliable benchmark. We not only analyze root-mean-square deviations from the experimental Cartesian coordinates, but also, for the first time, demonstrate how London dispersion and BSSE influence crystallographic R factors. Our conclusions parallel recent recommendations for the optimization of small gas-phase peptide structures made by some of the present authors: Hartree-Fock theory extended with Grimme's recent dispersion and BSSE corrections (HF-D3-gCP) is superior to popular density functional theory (DFT) approaches. Not only are statistical errors on average lower with HF-D3-gCP, but also the convergence behavior is much better. In particular, we show that the BP86/6-31G* approach should not be relied upon as a black-box method, despite its widespread use, as its success is based on an unpredictable cancellation of errors. Using HF-D3-gCP is technically straightforward, and we therefore encourage users of quantum-chemical methods to adopt this approach in future applications.
Monari, Antonio; Bendazzoli, Gian Luigi; Evangelisti, Stefano; Angeli, Celestino; Ben Amor, Nadia; Borini, Stefano; Maynau, Daniel; Rossi, Elda
2007-03-01
The dispersion interactions of the Ne2 dimer were studied using both the long-range perturbative and supramolecular approaches: for the long-range approach, full CI or string-truncated CI methods were used, while for the supramolecular treatments, the energy curves were computed by using configuration interaction with single and double excitation (CISD), coupled cluster with single and double excitation, and coupled-cluster with single and double (and perturbative) triple excitations. From the interatomic potential-energy curves obtained by the supramolecular approach, the C6 and C8 dispersion coefficients were computed via an interpolation scheme, and they were compared with the corresponding values obtained within the long-range perturbative treatment. We found that the lack of size consistency of the CISD approach makes this method completely useless to compute dispersion coefficients even when the effect of the basis-set superposition error on the dimer curves is considered. The largest full-CI space we were able to use contains more than 1 billion symmetry-adapted Slater determinants, and it is, to our knowledge, the largest calculation of second-order properties ever done at the full-CI level so far. Finally, a new data format and libraries (Q5Cost) have been used in order to interface different codes used in the present study.
Richard, Ryan M; Marshall, Michael S; Dolgounitcheva, O; Ortiz, J V; Brédas, Jean-Luc; Marom, Noa; Sherrill, C David
2016-02-01
In designing organic materials for electronics applications, particularly for organic photovoltaics (OPV), the ionization potential (IP) of the donor and the electron affinity (EA) of the acceptor play key roles. This makes OPV design an appealing application for computational chemistry since IPs and EAs are readily calculable from most electronic structure methods. Unfortunately reliable, high-accuracy wave function methods, such as coupled cluster theory with single, double, and perturbative triples [CCSD(T)] in the complete basis set (CBS) limit are too expensive for routine applications to this problem for any but the smallest of systems. One solution is to calibrate approximate, less computationally expensive methods against a database of high-accuracy IP/EA values; however, to our knowledge, no such database exists for systems related to OPV design. The present work is the first of a multipart study whose overarching goal is to determine which computational methods can be used to reliably compute IPs and EAs of electron acceptors. This part introduces a database of 24 known organic electron acceptors and provides high-accuracy vertical IP and EA values expected to be within ±0.03 eV of the true non-relativistic, vertical CCSD(T)/CBS limit. Convergence of IP and EA values toward the CBS limit is studied systematically for the Hartree-Fock, MP2 correlation, and beyond-MP2 coupled cluster contributions to the focal point estimates. PMID:26731487
NASA Astrophysics Data System (ADS)
Tsimpidi, A. P.; Karydis, V. A.; Pandis, S. N.; Zavala, M.; Lei, W.; Molina, L. T.
2007-12-01
Anthropogenic air pollution is an increasingly serious problem for public health, agriculture, and global climate. Organic material (OM) contributes ~ 20-50% to the total fine aerosol mass at continental mid-latitudes. Although OM accounts for a large fraction of PM2.5 concentration worldwide, the contributions of primary and secondary organic aerosol have been difficult to quantify. In this study, new primary and secondary organic aerosol modules were added to PMCAMx, a three dimensional chemical transport model (Gaydos et al., 2007), for use with the SAPRC99 chemistry mechanism (Carter, 2000; ENVIRON, 2006) based on recent smog chamber studies (Robinson et al., 2007). The new modeling framework is based on the volatility basis-set approach (Lane et al., 2007): both primary and secondary organic components are assumed to be semivolatile and photochemically reactive and are distributed in logarithmically spaced volatility bins. The emission inventory, which uses as starting point the MCMA 2004 official inventory (CAM, 2006), is modified and the primary organic aerosol (POA) emissions are distributed by volatility based on dilution experiments (Robinson et al., 2007). Sensitivity tests where POA is considered as nonvolatile and POA and SOA as chemically reactive are also described. In all cases PMCAMx is applied in the Mexico City Metropolitan Area during March 2006. The modeling domain covers a 180x180x6 km region in the MCMA with 3x3 km grid resolution. The model predictions are compared with Aerodyne's Aerosol Mass Spectrometry (AMS) observations from the MILAGRO Campaign. References Robinson, A. L.; Donahue, N. M.; Shrivastava, M. K.; Weitkamp, E. A.; Sage, A. M.; Grieshop, A. P.; Lane, T. E.; Pandis, S. N.; Pierce, J. R., 2007. Rethinking organic aerosols: semivolatile emissions and photochemical aging. Science 315, 1259-1262. Gaydos, T. M.; Pinder, R. W.; Koo, B.; Fahey, K. M.; Pandis, S. N., 2007. Development and application of a three- dimensional aerosol
NASA Astrophysics Data System (ADS)
Zhang, Q. J.; Beekmann, M.; Drewnick, F.; Freutel, F.; Schneider, J.; Crippa, M.; Prevot, A. S. H.; Baltensperger, U.; Poulain, L.; Wiedensohler, A.; Sciare, J.; Gros, V.; Borbon, A.; Colomb, A.; Michoud, V.; Doussin, J.-F.; Denier van der Gon, H. A. C.; Haeffelin, M.; Dupont, J.-C.; Siour, G.; Petetin, H.; Bessagnet, B.; Pandis, S. N.; Hodzic, A.; Sanchez, O.; Honoré, C.; Perrussel, O.
2013-06-01
Simulations with the chemistry transport model CHIMERE are compared to measurements performed during the MEGAPOLI (Megacities: Emissions, urban, regional and Global Atmospheric POLlution and climate effects, and Integrated tools for assessment and mitigation) summer campaign in the Greater Paris region in July 2009. The volatility-basis-set approach (VBS) is implemented into this model, taking into account the volatility of primary organic aerosol (POA) and the chemical aging of semi-volatile organic species. Organic aerosol is the main focus and is simulated with three different configurations with a modified treatment of POA volatility and modified secondary organic aerosol (SOA) formation schemes. In addition, two types of emission inventories are used as model input in order to test the uncertainty related to the emissions. Predictions of basic meteorological parameters and primary and secondary pollutant concentrations are evaluated, and four pollution regimes are defined according to the air mass origin. Primary pollutants are generally overestimated, while ozone is consistent with observations. Sulfate is generally overestimated, while ammonium and nitrate levels are well simulated with the refined emission data set. As expected, the simulation with non-volatile POA and a single-step SOA formation mechanism largely overestimates POA and underestimates SOA. Simulation of organic aerosol with the VBS approach taking into account the aging of semi-volatile organic compounds (SVOC) shows the best correlation with measurements. High-concentration events observed mostly after long-range transport are well reproduced by the model. Depending on the emission inventory used, simulated POA levels are either reasonable or underestimated, while SOA levels tend to be overestimated. Several uncertainties related to the VBS scheme (POA volatility, SOA yields, the aging parameterization), to emission input data, and to simulated OH levels can be responsible for this behavior
NASA Astrophysics Data System (ADS)
Knote, C. J.; Hodzic, A.; Aumont, B.; Madronich, S.
2014-12-01
Traditional understanding views secondary organic aerosol (SOA) formation in the atmosphere as continuous gas-phase oxidation of precursors such as isoprene, aromatics or alkanes. Recent research found that these oxidation products are also highly water soluble. It is further understood that the liquid-phase of cloud droplets as well as deliquesced particles could mediate SOA formation through chemistry in the aqueous-phase. While the effect of multi-phase processing has been studied in detailed for specific compounds like glyoxal or methylglyoxal, an integrated approach that considers the large number of individual compounds has been missing due to the complexity involved. In our work we explore the effects of multi-phase processing on secondary organic aerosol from an explicit modeling perspective.Volatility and solubility determine in which phase a given molecule will be found under given atmospheric conditions. Volatility has already been used to simplify the description of SOA formation in the gas-phase in what became known as the Volatility Basis Set approach (VBS). Compounds contributing to SOA formation are grouped by volatility and then treated as a whole. A number of studies extended the VBS by adding a second dimension like oxygen to carbon ratio or the mean oxidation state. In our work we use functional groups as second dimension.Using explicit oxidation chemistry modeling (GECKO-A) we derive SOA yields as well as their composition in terms of functional groups for commonly used precursors. We then investigate the effect of simply partitioning functional-group specific organic mass into cloud droplets and deliquesced aerosol based on their estimated solubility. Finally we apply simple chemistry in the aqueous-phase and relate changes in functional groups to changes in volatility and subsequent changes in partitioning between gas- and aerosol-phase.In our presentation we will explore the sensitivites of the multi-phase system in a box model setting with
Matsui, H.; Koike, Makoto; Kondo, Yutaka; Takami, A.; Fast, Jerome D.; Kanaya, Y.; Takigawa, M.
2014-09-16
Organic aerosol (OA) simulations using the volatility basis-set approach were made for East Asia and its outflow region. Model simulations were evaluated through comparisons with OA measured by aerosol mass spectrometers in and around Tokyo (at Komaba and Kisai in summer 2003 and 2004) and over the outflow region in East Asia (at Fukue and Hedo in spring 2009). The simulations with aging processes of organic vapors reasonably well reproduced mass concentrations, temporal variations, and formation efficiency of observed OA at all sites. As OA mass was severely underestimated in the simulations without the aging processes, the oxidations of organic vapors are essential for reasonable OA simulations over East Asia. By considering the aging processes, simulated OA concentrations considerably increased from 0.24 to 1.28 µg m-3 in the boundary layer over the whole of East Asia. OA formed from the interaction of anthropogenic and biogenic sources was also enhanced by the aging processes. The fraction of controllable OA was estimated to be 87 % of total OA over the whole of East Asia, showing that most of the OA in our simulations formed anthropogenically (controllable). A large portion of biogenic secondary OA (78 % of biogenic secondary OA) formed through the influence of anthropogenic sources. The high fraction of controllable OA in our simulations is likely because anthropogenic emissions are dominant over East Asia and OA formation is enhanced by anthropogenic sources and their aging processes. Both the amounts (from 0.18 to 1.12 µg m-3) and the fraction (from 75 % to 87 %) of controllable OA were increased by aging processes of organic vapors over East Asia.
Yoshida, Tatsusada; Hayashi, Takahisa; Mashima, Akira; Chuman, Hiroshi
2015-10-01
One of the most challenging problems in computer-aided drug discovery is the accurate prediction of the binding energy between a ligand and a protein. For accurate estimation of net binding energy ΔEbind in the framework of the Hartree-Fock (HF) theory, it is necessary to estimate two additional energy terms; the dispersion interaction energy (Edisp) and the basis set superposition error (BSSE). We previously reported a simple and efficient dispersion correction, Edisp, to the Hartree-Fock theory (HF-Dtq). In the present study, an approximation procedure for estimating BSSE proposed by Kruse and Grimme, a geometrical counterpoise correction (gCP), was incorporated into HF-Dtq (HF-Dtq-gCP). The relative weights of the Edisp (Dtq) and BSSE (gCP) terms were determined to reproduce ΔEbind calculated with CCSD(T)/CBS or /aug-cc-pVTZ (HF-Dtq-gCP (scaled)). The performance of HF-Dtq-gCP (scaled) was compared with that of B3LYP-D3(BJ)-bCP (dispersion corrected B3LYP with the Boys and Bernadi counterpoise correction (bCP)), by taking ΔEbind (CCSD(T)-bCP) of small non-covalent complexes as 'a golden standard'. As a critical test, HF-Dtq-gCP (scaled)/6-31G(d) and B3LYP-D3(BJ)-bCP/6-31G(d) were applied to the complex model for HIV-1 protease and its potent inhibitor, KNI-10033. The present results demonstrate that HF-Dtq-gCP (scaled) is a useful and powerful remedy for accurately and promptly predicting ΔEbind between a ligand and a protein, albeit it is a simple correction procedure.
NASA Astrophysics Data System (ADS)
Maroulis, George
1998-04-01
The electric multipole moments, dipole and quadrupole polarizability and hyperpolarizability of hydrogen chloride have been determined from an extensive and systematic study based on finite-field fourth-order many-body perturbation theory and coupled-cluster calculations. Our best values for the dipole, quadrupole, octopole and hexadecapole moment at the experimental internuclear separation of Re=2.408645a0 are μ=0.4238ea0, Θ=2.67ea02, Ω=3.94ea03, and Φ=13.37ea04, respectively. For the mean and the anisotropy of the dipole polarizability ααβ we recommend ᾱ=17.41±0.02 and Δα=1.60±0.03e2a02Eh-1. For the mean value of the first dipole hyperpolarizability βαβγ we advance β¯=-6.8±0.3e3a03Eh-2. Extensive calculations with a [8s6p6d3f/5s4p2d1f] basis set at the CCSD(T) level of theory yield the R-dependence of the Cartesian components and the mean of the second dipole hyperpolarizability γαβγδ(R)/e4a04Eh-3 around Re as γzzzz(R)=1907+1326(R-Re)+570(R-Re)2+10(R-Re)3-40(R-Re)4, γxxxx(R)=3900+747(R-Re)-65(R-Re)2-38(R-Re)3-7(R-Re)4, γxxzz(R)=962+222(R-Re)+88(R-Re)2+49(R-Re)3+5(R-Re)4, γ¯(R)=3230+841(R-Re)+151(R-Re)2+21(R-Re)3-9(R-Re)4, with z as the molecular axis. The present investigation suggests an estimate of (26.7±0.3)×102e4a04Eh-3 for the Hartree-Fock limit of the mean value γ¯ at Re. CCSD(T) calculations with basis sets of [8s6p6d3f/5s4p2d1f] and [9s7p5d4f/6s5p4d1f] size and MP4 calculations with the even larger [15s12p7d3f/12s7p2d1f] give (7.0±0.3)×102e4a04Eh-3 for the electron correlation effects for this property, thus leading to a recommended value of γ¯=(33.7±0.6)×102e4a04Eh-3. For the quadrupole polarizability Cαβ,γδ/e2a04Eh-1 at Re our best values are Czz,zz=41.68, Cxz,xz=26.11, and Cxx,xx=35.38, calculated with the [9s7p5d4f/6s5p4d1f] basis set at the CCSD(T) level of theory. The following CCSD(T) values were obtained with [8s6p6d3f/5s4p2d1f] at Re: dipole-quadrupole polarizability Aα,βγ/e2a03Eh-1, Az,zz=14.0, and
Solomonik, Victor G; Stanton, John F; Boggs, James E
2005-03-01
The molecular equilibrium geometries, quadratic and cubic force constants, vibrational frequencies, and infrared intensities of scandium and iron trifluorides are determined ab initio with a sequence of atomic natural orbital basis sets using the CCSD(T) treatment of electron correlation. The largest basis set of spdf ghi quality contains 462 contracted Gaussian functions. Relativistic corrections are applied to compute the equilibrium geometries and vibrational frequencies. The cubic force constants are used to estimate vibrational corrections to the effective r(g) internuclear distances determined in the gas electron diffraction experiments. The computed molecular properties are extrapolated to the complete basis-set limit. The predicted values are compared to the available experimental data; uncertainties and inconsistencies in these data are then discussed. PMID:15836143
Snijders, J.G.; Vernooijs, P.; Baerends, E.J.
1981-11-01
Basis-set expansions are presented for the Hartree--Fock--Slater (HFS) orbitals of the neutral elements Fr--Lr (Z = 87--103). The Slater-type functions used in these expansions are found by an efficient fitting procedure to the Herman--Skillman numerical HFS orbitals. The expansions are of single-zera, double-zeta, and triple-zeta-valence (extended) quality. Comparisons of orbital energies with the numerical values are given for all elements. similar basis sets for all the remaining elements are available on request.
Huang, Xinchuan; Valeev, Edward F; Lee, Timothy J
2010-12-28
One-particle basis set extrapolation is compared with one of the new R12 methods for computing highly accurate quartic force fields (QFFs) and spectroscopic data, including molecular structures, rotational constants, and vibrational frequencies for the H(2)O, N(2)H(+), NO(2)(+), and C(2)H(2) molecules. In general, agreement between the spectroscopic data computed from the best R12 and basis set extrapolation methods is very good with the exception of a few parameters for N(2)H(+) where it is concluded that basis set extrapolation is still preferred. The differences for H(2)O and NO(2)(+) are small and it is concluded that the QFFs from both approaches are more or less equivalent in accuracy. For C(2)H(2), however, a known one-particle basis set deficiency for C-C multiple bonds significantly degrades the quality of results obtained from basis set extrapolation and in this case the R12 approach is clearly preferred over one-particle basis set extrapolation. The R12 approach used in the present study was modified in order to obtain high precision electronic energies, which are needed when computing a QFF. We also investigated including core-correlation explicitly in the R12 calculations, but conclude that current approaches are lacking. Hence core-correlation is computed as a correction using conventional methods. Considering the results for all four molecules, it is concluded that R12 methods will soon replace basis set extrapolation approaches for high accuracy electronic structure applications such as computing QFFs and spectroscopic data for comparison to high-resolution laboratory or astronomical observations, provided one uses a robust R12 method as we have done here. The specific R12 method used in the present study, CCSD(T)(R12), incorporated a reformulation of one intermediate matrix in order to attain machine precision in the electronic energies. Final QFFs for N(2)H(+) and NO(2)(+) were computed, including basis set extrapolation, core-correlation, scalar
NASA Astrophysics Data System (ADS)
Kobus, J.; Moncrieff, D.; Wilson, S.
2007-03-01
We investigate the accuracy with which the electric dipole polarizability, αzz, and the hyperpolarizability, βzzz, can be calculated by using the algebraic approximation, i.e. finite basis set expansions, and by means of the finite difference method in calculations for the ground states of the 14 electron systems N2, CO and BF within the Hartree-Fock model at their respective experimental equilibrium geometries. For a well-chosen grid, the finite difference technique can provide Hartree-Fock energy and dipole moment expectation values approaching machine precision which can be used to assess the accuracy of corresponding calculations carried out within the algebraic approximation. The finite field approximation is used to determine polarizabilities and hyperpolarizabilities from finite difference Hartree-Fock dipole moment expectation values. The results are compared with finite basis set calculations of the corresponding quantities which are carried out analytically using coupled perturbed Hartree-Fock theory. For the N2 molecule, the Hartree-Fock polarizability is found to be 14.9512 au within the finite basis set approximation and 14.945 au within the finite difference approach. For the CO molecule, the corresponding results are 14.4668 au and 14.4668 au, whilst for the BF molecule the values are 16.6450 au and 16.6450 au, respectively. The Hartree-Fock hyperpolarizability of the CO molecule is found to be 31.4081 au and 31.411 au within the finite basis set and finite difference approximations, respectively. The corresponding hyperpolarizability values for the BF molecule are 63.9687 au and 63.969 au, respectively. This paper is dedicated to Victor R Saunders, on his official retirement from Daresbury Laboratory.
Egetemeir, Johanna; Stenneken, Prisca; Koehler, Saskia; Fallgatter, Andreas J.; Herrmann, Martin J.
2011-01-01
Many every-day life situations require two or more individuals to execute actions together. Assessing brain activation during naturalistic tasks to uncover relevant processes underlying such real-life joint action situations has remained a methodological challenge. In the present study, we introduce a novel joint action paradigm that enables the assessment of brain activation during real-life joint action tasks using functional near-infrared spectroscopy (fNIRS). We monitored brain activation of participants who coordinated complex actions with a partner sitting opposite them. Participants performed table setting tasks, either alone (solo action) or in cooperation with a partner (joint action), or they observed the partner performing the task (action observation). Comparing joint action and solo action revealed stronger activation (higher [oxy-Hb]-concentration) during joint action in a number of areas. Among these were areas in the inferior parietal lobule (IPL) that additionally showed an overlap of activation during action observation and solo action. Areas with such a close link between action observation and action execution have been associated with action simulation processes. The magnitude of activation in these IPL areas also varied according to joint action type and its respective demand on action simulation. The results validate fNIRS as an imaging technique for exploring the functional correlates of interindividual action coordination in real-life settings and suggest that coordinating actions in real-life situations requires simulating the actions of the partner. PMID:21927603
Sherrill, C David; Takatani, Tait; Hohenstein, Edward G
2009-09-24
Large, correlation-consistent basis sets have been used to very closely approximate the coupled-cluster singles, doubles, and perturbative triples [CCSD(T)] complete basis set potential energy curves of several prototype nonbonded complexes, the sandwich, T-shaped, and parallel-displaced benzene dimers, the methane-benzene complex, the H2S-benzene complex, and the methane dimer. These benchmark potential energy curves are used to assess the performance of several methods for nonbonded interactions, including various spin-component-scaled second-order perturbation theory (SCS-MP2) methods, the spin-component-scaled coupled-cluster singles and doubles method (SCS-CCSD), density functional theory empirically corrected for dispersion (DFT-D), and the meta-generalized-gradient approximation functionals M05-2X and M06-2X. These approaches generally provide good results for the test set, with the SCS methods being somewhat more robust. M05-2X underbinds for the test cases considered, while the performances of DFT-D and M06-2X are similar. Density fitting, dual basis, and local correlation approximations all introduce only small errors in the interaction energies but can speed up the computations significantly, particulary when used in combination.
Hendriksen, Ilse C. E.; White, Lisa J.; Veenemans, Jacobien; Mtove, George; Woodrow, Charles; Amos, Ben; Saiwaew, Somporn; Gesase, Samwel; Nadjm, Behzad; Silamut, Kamolrat; Joseph, Sarah; Chotivanich, Kesinee; Day, Nicholas P. J.; von Seidlein, Lorenz; Verhoef, Hans; Reyburn, Hugh; White, Nicholas J.; Dondorp, Arjen M.
2013-01-01
Background. In malaria-endemic settings, asymptomatic parasitemia complicates the diagnosis of malaria. Histidine-rich protein 2 (HRP2) is produced by Plasmodium falciparum, and its plasma concentration reflects the total body parasite burden. We aimed to define the malaria-attributable fraction of severe febrile illness, using the distributions of plasma P. falciparum HRP2 (PfHRP2) concentrations from parasitemic children with different clinical presentations. Methods. Plasma samples were collected from and peripheral blood slides prepared for 1435 children aged 6−60 months in communities and a nearby hospital in northeastern Tanzania. The study population included children with severe or uncomplicated malaria, asymptomatic carriers, and healthy control subjects who had negative results of rapid diagnostic tests. The distributions of plasma PfHRP2 concentrations among the different groups were used to model severe malaria-attributable disease. Results. The plasma PfHRP2 concentration showed a close correlation with the severity of infection. PfHRP2 concentrations of >1000 ng/mL denoted a malaria-attributable fraction of severe disease of 99% (95% credible interval [CI], 96%–100%), with a sensitivity of 74% (95% CI, 72%–77%), whereas a concentration of <200 ng/mL denoted severe febrile illness of an alternative diagnosis in >10% (95% CI, 3%–27%) of patients. Bacteremia was more common among patients in the lowest and highest PfHRP2 concentration quintiles. Conclusions. The plasma PfHRP2 concentration defines malaria-attributable disease and distinguishes severe malaria from coincidental parasitemia in African children in a moderate-to-high transmission setting. PMID:23136222
NASA Astrophysics Data System (ADS)
Yang, Yue; Weaver, Michael N.; Merz, Kenneth M.
2009-08-01
Computational chemists have long demonstrated great interest in finding ways to reliably and accurately predict the molecular properties for transition-metal-containing complexes. This study is a continuation of our validation efforts of density functional theory (DFT) methods when applied to transition-metal-containing systems (Riley, K.E.; Merz, K. M., Jr. J. Phys. Chem. 2007, 111, 6044-6053). In our previous work we examined DFT using all-electron basis sets, but approaches incorporating effective core potentials (ECPs) are effective in reducing computational expense. With this in mind, our efforts were expanded to include evaluation of the performance of the basis set derived to approximate such an approach as well on the same set of density functionals. Indeed, employing an ECP basis such as LANL2DZ (Los Alamos National Laboratory 2 double ζ) for transition metals, while using all-electron basis sets for all other non-transition-metal atoms, has become more and more popular in computations on transition-metal-containing systems. In this study, we assess the performance of 12 different DFT functionals, from the GGA (generalized gradient approximation), hybrid-GGA, meta-GGA, and hybrid-meta-GGA classes, respectively, along with the 6-31+G** + LANL2DZ (on the transition metal) mixed basis set in predicting two important molecular properties, heats of formation and ionization potentials, for 94 and 58 systems containing first-row transition metals from Ti to Zn, which are all in the third row of the periodic table. An interesting note is that the inclusion of the exact exchange term in density functional methods generally increases the accuracy of ionization potential prediction for the hybrid-GGA methods but decreases the reliability of determining the heats of formation for transition-metal-containing complexes for all hybrid density functional methods. The hybrid-GGA functional B3LYP gives the best performance in predicting the ionization potentials, while the
Singh, Poonam; Dhiman, Ramesh C
2016-01-01
In India, malaria transmission is prevalent across diverse geologies and ecologies. Temperature is one of the key determinants of malarial transmission, causing low endemicity in some areas than in others. Using a degree-day model, we estimated the maximum and minimum possible number of days needed to complete a malarial sporogonic cycle (SC), in addition to the possible number of SCs for Plasmodium vivax and Plasmodium falciparum under two different ecological settings with either low or high endemicity for malaria at different elevations. In Raikhalkhatta (in the Himalayan foothills) SCs were modeled as not occurring from November to February, whereas in Gandhonia village (forested hills), all but only one month were suitable for malarial SCs. A minimum of 6 days and maximum of 46 days were required for completion of one SC. Forested hilly areas were more suitable for malaria parasite development in terms of SCs (25 versus 21 for P. falciparum and 32 versus 27 for P. vivax). Degree-days also provided a climatic explanation for the current transmission of malaria at different elevations. The calculation of degree-days and possible SC has applications in the regional analysis of transmission dynamics and management of malaria in view of climate change.
Gao, Wei; Feng, Huajie; Xuan, Xiaopeng; Chen, Liuping
2012-10-01
An assessment study is presented about energy decomposition analysis (EDA) in combination with DFT including revised dispersion correction (DFT-D3) with Slater-type orbital (STO) basis set. There has been little knowledge about the performance of the EDA + DFT-D3 concerning STOs. In this assessment such an approach was applied to calculate noncovalent interaction energies and their corresponding components. Complexes in S22 set were used to evaluate the performance of EDA in conjunction with four representative types of GGA-functionals of DFT-D3 (BP86-D3, BLYP-D3, PBE-D3 and SSB-D3) with three STO basis sets ranging in complexity from DZP, TZ2P to QZ4P. The results showed that the approach of EDA + BLYP-D3/TZ2P has a better performance not only in terms of calculating noncovalent interaction energy quantitatively but also in analyzing corresponding energy components qualitatively. This approach (EDA + BLYP-D3/TZ2P) was thus applied further to two representative large-system complexes including porphine dimers and fullerene aggregates to gain a better insight into binding characteristics.
NASA Astrophysics Data System (ADS)
Zheng, Jingjing; Gour, Jeffrey R.; Lutz, Jesse J.; Włoch, Marta; Piecuch, Piotr; Truhlar, Donald G.
2008-01-01
The CCSD, CCSD(T), and CR-CC(2,3) coupled cluster methods, combined with five triple-zeta basis sets, namely, MG3S, aug-cc-pVTZ, aug-cc-pV(T +d)Z, aug-cc-pCVTZ, and aug-cc-pCV(T +d)Z, are tested against the DBH24 database of diverse reaction barrier heights. The calculations confirm that the inclusion of connected triple excitations is essential to achieving high accuracy for thermochemical kinetics. They show that various noniterative ways of incorporating connected triple excitations in coupled cluster theory, including the CCSD(T) approach, the full CR-CC(2,3) method, and approximate variants of CR-CC(2,3) similar to the triples corrections of the CCSD(2) approaches, are all about equally accurate for describing the effects of connected triply excited clusters in studies of activation barriers. The effect of freezing core electrons on the results of the CCSD, CCSD(T), and CR-CC(2,3) calculations for barrier heights is also examined. It is demonstrated that to include core correlation most reliably, a basis set including functions that correlate the core and that can treat core-valence correlation is required. On the other hand, the frozen-core approximation using valence-optimized basis sets that lead to relatively small computational costs of CCSD(T) and CR-CC(2,3) calculations can achieve almost as high accuracy as the analogous fully correlated calculations.
Orlando, Roberto; Lacivita, Valentina; Bast, Radovan; Ruud, Kenneth
2010-06-28
The computational scheme for the evaluation of the second-order electric susceptibility tensor in periodic systems, recently implemented in the CRYSTAL code within the coupled perturbed Hartree-Fock (HF) scheme, has been extended to local-density, gradient-corrected, and hybrid density functionals (coupled-perturbed Kohn-Sham) and applied to a set of cubic and hexagonal semiconductors. The method is based on the use of local basis sets and analytical calculation of derivatives. The high-frequency dielectric tensor (epsilon(infinity)) and second-harmonic generation susceptibility (d) have been calculated with hybrid functionals (PBE0 and B3LYP) and the HF approximation. Results are compared with the values of epsilon(infinity) and d obtained from previous plane-wave local density approximation or generalized gradient approximation calculations and from experiment. The agreement is in general good, although comparison with experiment is affected by a certain degree of uncertainty implicit in the experimental techniques.
Allsman, R.; Barrett, K.; Busby, L.; Chiu, Y.; Crotinger, J.; Dubois, B.; Dubois, P.F.; Langdon, B.; Motteler, Z.C.; Takemoto, J.; Taylor, S.; Willmann, P.; Wilson, S. )
1993-08-01
BASIS9.4 is a system for developing interactive computer programs in Fortran, with some support for C and C++ as well. Using BASIS9.4 you can create a program that has a sophisticated programming language as its user interface so that the user can set, calculate with, and plot, all the major variables in the program. The program author writes only the scientific part of the program; BASIS9.4 supplies an environment in which to exercise that scientific programming which includes an interactive language, an interpreter, graphics, terminal logs, error recovery, macros, saving and retrieving variables, formatted I/O, and online documentation.
NASA Astrophysics Data System (ADS)
Dattani, Nikesh S.; Sharma, Sandeep; Alavi, Ali
2016-06-01
Being the simplest uncharged homonuclear dimer after H_2 that has a stable ground state, Li_2 is one of the most important benchmark systems for theory and experiment. In 1930, Delbruck used Li_2 to test his theory of homopolar binding, and it was used again and again as a prototype to test what have now become some of the most ubiquitous concepts in molecular physics (LCAO, SCF, MO, just to name a few). Experimentally, Roscoe and Schuster studied alkali dimers back in 1874. At the dawn of quantum mechanics, the emerging types of spectroscopic analyses we now use today, were tested on Li_2 in the labs of Wurm (1928), Harvey (1929), Lewis (1931), and many others, independently. Li_2 was at the centre of the development of PFOODR in the 80s, and PAS in the 90s; and Lithium Bose-Einstein condensates were announced only 1 month after the Nobel Prize winning BEC announcement in 1995. Even now in the 2010s, numerous experimental and theoretical studies on Li have tested QED up to the 7th power of the fine structure constant. Li_2 has also been of interest to sub-atomic physicists, as it was spectroscopic measurements on ^7Li_2 that determined the spin of ^7Li to be 3/2 in 1931; and Li_2 has been proposed in 2014 as a candidate for the first ``halo nucleonic molecule". The lowest triplet state a(1^3Σ_u^+) is an excellent benchmark system for all newly emerging ab initio techniques because it has only 6e^-, its potential is only 334 cm-1 deep, it avoids harsh complications from spin-orbit coupling, and it is the deepest potential for which all predicted vibrational energy levels have been observed with 0.0001 cm-1 precision. However the current best ab initio potentials do not even yield all vibrational energy spacings correct to within 1 cm-1. This could be because the calculation was only done on a cc-pV5Z basis set, or because the QCISD(T,full) method that the authors used, only considered triple excitations while a full CI calculation should include up to hexuple
Li, Y. Q.; Ma, F. C.; Sun, M. T.
2013-10-21
A full three-dimensional global potential energy surface is reported first time for the title system, which is important for the photodissociation processes. It is obtained using double many-body expansion theory and an extensive set of accurate ab initio energies extrapolated to the complete basis set limit. Such a work can be recommended for dynamics studies of the N({sup 2}D) + H{sub 2} reaction, a reliable theoretical treatment of the photodissociation dynamics and as building blocks for constructing the double many-body expansion potential energy surface of larger nitrogen/hydrogen containing systems. In turn, a preliminary theoretical study of the reaction N({sup 2}D)+H{sub 2}(X{sup 1}Σ{sub g}{sup +})(ν=0,j=0)→NH(a{sup 1}Δ)+H({sup 2}S) has been carried out with the method of quasi-classical trajectory on the new potential energy surface. Integral cross sections and thermal rate constants have been calculated, providing perhaps the most reliable estimate of the integral cross sections and the rate constants known thus far for such a reaction.
Campos, Cesar T; Jorge, Francisco E; Alves, Júlia M A
2012-09-01
Recently, segmented all-electron contracted double, triple, quadruple, quintuple, and sextuple zeta valence plus polarization function (XZP, X = D, T, Q, 5, and 6) basis sets for the elements from H to Ar were constructed for use in conjunction with nonrelativistic and Douglas-Kroll-Hess Hamiltonians. In this work, in order to obtain a better description of some molecular properties, the XZP sets for the second-row elements were augmented with high-exponent d "inner polarization functions," which were optimized in the molecular environment at the second-order Møller-Plesset level. At the coupled cluster level of theory, the inclusion of tight d functions for these elements was found to be essential to improve the agreement between theoretical and experimental zero-point vibrational energies (ZPVEs) and atomization energies. For all of the molecules studied, the ZPVE errors were always smaller than 0.5 %. The atomization energies were also improved by applying corrections due to core/valence correlation and atomic spin-orbit effects. This led to estimates for the atomization energies of various compounds in the gaseous phase. The largest error (1.2 kcal mol(-1)) was found for SiH(4).
Brndiar, Ján; Štich, Ivan
2012-07-10
Interaction energies of small model van der Waals fragments of group VA (P, As, Sb) and group VIA (S, Se, Te) are calculated using the complete basis set CCSD(T) method and compared to density functional results with approximate treatment of dispersion interaction using vdW-DF- and DFT-D-types of theories. These simple systems show surprising diversity of electronic properties ranging from more "metallic" to more "insulator" like, a property which needs to be captured in the approximate methods. While none of the standard approximate DFT theories provides an entirely satisfactory description of all the systems, we identify the most reliable approaches of each type. In addition, we show that results can be further tuned to chemical accuracy. In vdW-DF theory, guided by physical insights and the availability of quasi-exact CCSD(T) results, we supply the missing parts of correlation by matching an appropriate hybrid/semilocal exchange-correlation functional to describe short-/medium-range correlations accurately. In the DFT-D-type of theories, we reparametrize the empirical dispersion term. Since for such an accurate treatment benchmark calculations are needed, which typically is feasible only for a finite cluster, we argue that the cluster based model of the exchange-correlation hole is transferrable also to extended systems with vdW dispersion interactions.
Roper, Ian P E; Besley, Nicholas A
2016-03-21
The simulation of X-ray emission spectra of transition metal complexes with time-dependent density functional theory (TDDFT) is investigated. X-ray emission spectra can be computed within TDDFT in conjunction with the Tamm-Dancoff approximation by using a reference determinant with a vacancy in the relevant core orbital, and these calculations can be performed using the frozen orbital approximation or with the relaxation of the orbitals of the intermediate core-ionised state included. Both standard exchange-correlation functionals and functionals specifically designed for X-ray emission spectroscopy are studied, and it is shown that the computed spectral band profiles are sensitive to the exchange-correlation functional used. The computed intensities of the spectral bands can be rationalised by considering the metal p orbital character of the valence molecular orbitals. To compute X-ray emission spectra with the correct energy scale allowing a direct comparison with experiment requires the relaxation of the core-ionised state to be included and the use of specifically designed functionals with increased amounts of Hartree-Fock exchange in conjunction with high quality basis sets. A range-corrected functional with increased Hartree-Fock exchange in the short range provides transition energies close to experiment and spectral band profiles that have a similar accuracy to those from standard functionals.
Miliordos, Evangelos; Xantheas, Sotiris S
2015-06-21
We report MP2 and Coupled Cluster Singles, Doubles, and perturbative Triples [CCSD(T)] binding energies with basis sets up to pentuple zeta quality for the (H2O)m=2-6,8 water clusters. Our best CCSD(T)/Complete Basis Set (CBS) estimates are -4.99 ± 0.04 kcal/mol (dimer), -15.8 ± 0.1 kcal/mol (trimer), -27.4 ± 0.1 kcal/mol (tetramer), -35.9 ± 0.3 kcal/mol (pentamer), -46.2 ± 0.3 kcal/mol (prism hexamer), -45.9 ± 0.3 kcal/mol (cage hexamer), -45.4 ± 0.3 kcal/mol (book hexamer), -44.3 ± 0.3 kcal/mol (ring hexamer), -73.0 ± 0.5 kcal/mol (D2d octamer), and -72.9 ± 0.5 kcal/mol (S4 octamer). We have found that the percentage of both the uncorrected (De) and basis set superposition error-corrected (De (CP)) binding energies recovered with respect to the CBS limit falls into a narrow range on either sides of the CBS limit for each basis set for all clusters. In addition, this range decreases upon increasing the basis set. Relatively accurate estimates (within <0.5%) of the CBS limits can be obtained when using the "23, 13" (for the AVDZ set) or the "12, 12" (for the AVTZ, AVQZ, and AV5Z sets) mixing ratio between De and De (CP). These mixing rations are determined via a least-mean-squares approach from a dataset that encompasses clusters of various sizes. Based on those findings, we propose an accurate and efficient computational protocol that can be presently used to estimate accurate binding energies of water clusters containing up to 30 molecules (for CCSD(T)) and up to 100 molecules (for MP2).
Nori-Shargh, Davood; Mousavi, Seiedeh Negar; Kayi, Hakan
2014-05-01
Complete basis set CBS-4, hybrid-density functional theory (hybrid-DFT: B3LYP/6-311+G**) based methods and natural bond orbital (NBO) interpretations have been used to examine the contributions of the hyperconjugative, electrostatic, and steric effects on the conformational behaviors of trans-2,3-dihalo-1,4-diselenane [halo = F (1), Cl (2), Br (3)] and trans-2,5-dihalo-1,4-diselenane [halo = F (4), Cl (5), Br (6)]. Both levels of theory showed that the axial conformation stability, compared to its corresponding equatorial conformation, decreases from compounds 1 → 3 and 4 → 6. Based on the results obtained from the NBO analysis, there are significant anomeric effects for compounds 1-6. The anomeric effect associated with the electron delocalization is in favor of the axial conformation and increases from compounds 1 → 3 and 4 → 6. On the other hand, dipole moment differences between the axial and equatorial conformations [Δ(μ(eq)-μ(ax)] decrease from compounds 1 → 3. Although Δ(μ(eq)-μ(ax)) parameter decreases from compound 1 to compound 3, the dipole moment values of the axial conformations are smaller than those of their corresponding equatorial conformations. Therefore, the anomeric effect associated with the electron delocalizations (for halogen-C-Se segments) and the electrostatic model associated with the dipole-dipole interactions fail to account for the increase of the equatorial conformations stability on going from compound 1 to compound 3. Since there is no dipole moment for the axial and equatorial conformations of compounds 4-6, consequently, the conformational preferences in compounds 1-6 is in general dictated by the steric hindrance factor associated with the 1,3-syn-axial repulsions. Importantly, the CBS-4 results show that the entropy difference (∆S) between the equatorial axial conformations increases from compounds 1 → 3 and 4 → 6. This fact can be explained by the anomeric effect associated
BASIS9.4. The Basis Code Development System
Allsman, R.; Barrett, K.; Busby, L.; Chiu, Y.; Crotinger, J.; Dubois, B.; Dubois, P.F.; Langdon, B.; Motteler, Z.C.; Takemoto, J.; Taylor, S.; Willmann, P.; Wilson, S.
1993-08-01
BASIS9.4 is a system for developing interactive computer programs in Fortran, with some support for C and C++ as well. Using BASIS9.4 you can create a program that has a sophisticated programming language as its user interface so that the user can set, calculate with, and plot, all the major variables in the program. The program author writes only the scientific part of the program; BASIS9.4 supplies an environment in which to exercise that scientific programming which includes an interactive language, an interpreter, graphics, terminal logs, error recovery, macros, saving and retrieving variables, formatted I/O, and online documentation.
NASA Astrophysics Data System (ADS)
Woolf, Lawrence
2016-03-01
A wide variety of reports have been issued recently concerning the skills, knowledge, and attitudes needed by employees to be successful. This talk will review findings from reports from the major science and engineering disciplines, from surveys of employers, and from interviews with recent undergraduate physics graduates. Also to be discussed is the correlation between these findings and the detailed J-TUPP recommendations for the skills and knowledge needed by the next generation of undergraduate physics degree holders to be prepared for a diverse set of careers.
Perczel, András; Farkas, Odön; Jákli, Imre; Topol, Igor A; Csizmadia, Imre G
2003-07-15
At the dawn of the new millenium, new concepts are required for a more profound understanding of protein structures. Together with NMR and X-ray-based 3D-structure determinations in silico methods are now widely accepted. Homology-based modeling studies, molecular dynamics methods, and quantum mechanical approaches are more commonly used. Despite the steady and exponential increase in computational power, high level ab initio methods will not be in common use for studying the structure and dynamics of large peptides and proteins in the near future. We are presenting here a novel approach, in which low- and medium-level ab initio energy results are scaled, thus extrapolating to a higher level of information. This scaling is of special significance, because we observed previously on molecular properties such as energy, chemical shielding data, etc., determined at a higher theoretical level, do correlate better with experimental data, than those originating from lower theoretical treatments. The Ramachandran surface of an alanine dipeptide now determined at six different levels of theory [RHF and B3LYP 3-21G, 6-31+G(d) and 6-311++G(d,p)] serves as a suitable test. Minima, first-order critical points and partially optimized structures, determined at different levels of theory (SCF, DFT), were completed with high level energy calculations such as MP2, MP4D, and CCSD(T). For the first time three different CCSD(T) sets of energies were determined for all stable B3LYP/6-311++G(d,p) minima of an alanine dipeptide. From the simplest ab initio data (e.g., RHF/3-21G) to more complex results [CCSD(T)/6-311+G(d,p)//B3LYP/6-311++G(d,p)] all data sets were compared, analyzed in a comprehensive manner, and evaluated by means of statistics.
The Basis Code Development System
1994-03-15
BASIS9.4 is a system for developing interactive computer programs in Fortran, with some support for C and C++ as well. Using BASIS9.4 you can create a program that has a sophisticated programming language as its user interface so that the user can set, calculate with, and plot, all the major variables in the program. The program author writes only the scientific part of the program; BASIS9.4 supplies an environment in which to exercise that scientificmore » programming which includes an interactive language, an interpreter, graphics, terminal logs, error recovery, macros, saving and retrieving variables, formatted I/O, and online documentation.« less
R.J. Garrett
2002-01-14
As part of the internal Integrated Safety Management Assessment verification process, it was determined that there was a lack of documentation that summarizes the safety basis of the current Yucca Mountain Project (YMP) site characterization activities. It was noted that a safety basis would make it possible to establish a technically justifiable graded approach to the implementation of the requirements identified in the Standards/Requirements Identification Document. The Standards/Requirements Identification Documents commit a facility to compliance with specific requirements and, together with the hazard baseline documentation, provide a technical basis for ensuring that the public and workers are protected. This Safety Basis Report has been developed to establish and document the safety basis of the current site characterization activities, establish and document the hazard baseline, and provide the technical basis for identifying structures, systems, and components (SSCs) that perform functions necessary to protect the public, the worker, and the environment from hazards unique to the YMP site characterization activities. This technical basis for identifying SSCs serves as a grading process for the implementation of programs such as Conduct of Operations (DOE Order 5480.19) and the Suspect/Counterfeit Items Program. In addition, this report provides a consolidated summary of the hazards analyses processes developed to support the design, construction, and operation of the YMP site characterization facilities and, therefore, provides a tool for evaluating the safety impacts of changes to the design and operation of the YMP site characterization activities.
ERIC Educational Resources Information Center
Giorgis, Cyndi; Johnson, Nancy J.
2002-01-01
Presents annotations of approximately 30 titles grouped in text sets. Defines a text set as five to ten books on a particular topic or theme. Discusses books on the following topics: living creatures; pirates; physical appearance; natural disasters; and the Irish potato famine. (SG)
Authorization basis requirements comparison report
Brantley, W.M.
1997-08-18
The TWRS Authorization Basis (AB) consists of a set of documents identified by TWRS management with the concurrence of DOE-RL. Upon implementation of the TWRS Basis for Interim Operation (BIO) and Technical Safety Requirements (TSRs), the AB list will be revised to include the BIO and TSRs. Some documents that currently form part of the AB will be removed from the list. This SD identifies each - requirement from those documents, and recommends a disposition for each to ensure that necessary requirements are retained when the AB is revised to incorporate the BIO and TSRs. This SD also identifies documents that will remain part of the AB after the BIO and TSRs are implemented. This document does not change the AB, but provides guidance for the preparation of change documentation.
Performance Basis for Airborne Separation
NASA Technical Reports Server (NTRS)
Wing, David J.
2008-01-01
Emerging applications of Airborne Separation Assistance System (ASAS) technologies make possible new and powerful methods in Air Traffic Management (ATM) that may significantly improve the system-level performance of operations in the future ATM system. These applications typically involve the aircraft managing certain components of its Four Dimensional (4D) trajectory within the degrees of freedom defined by a set of operational constraints negotiated with the Air Navigation Service Provider. It is hypothesized that reliable individual performance by many aircraft will translate into higher total system-level performance. To actually realize this improvement, the new capabilities must be attracted to high demand and complexity regions where high ATM performance is critical. Operational approval for use in such environments will require participating aircraft to be certified to rigorous and appropriate performance standards. Currently, no formal basis exists for defining these standards. This paper provides a context for defining the performance basis for 4D-ASAS operations. The trajectory constraints to be met by the aircraft are defined, categorized, and assessed for performance requirements. A proposed extension of the existing Required Navigation Performance (RNP) construct into a dynamic standard (Dynamic RNP) is outlined. Sample data is presented from an ongoing high-fidelity batch simulation series that is characterizing the performance of an advanced 4D-ASAS application. Data of this type will contribute to the evaluation and validation of the proposed performance basis.
Neuromechanical Basis of Kinesiology.
ERIC Educational Resources Information Center
Enoka, Roger M.
This textbook provides a scientific basis for the study of human motion. The eight chapters are organized under three major sections. Part One--The Force-Motion Relationship--contains chapters on (1) motion; (2) force; (3) types of movement analysis. In Part Two--The Simple Joint System--chapters concern (4) simple joint system components; (5)…
SETS. Set Equation Transformation System
Worrell, R.B.
1992-01-13
SETS is used for symbolic manipulation of Boolean equations, particularly the reduction of equations by the application of Boolean identities. It is a flexible and efficient tool for performing probabilistic risk analysis (PRA), vital area analysis, and common cause analysis. The equation manipulation capabilities of SETS can also be used to analyze noncoherent fault trees and determine prime implicants of Boolean functions, to verify circuit design implementation, to determine minimum cost fire protection requirements for nuclear reactor plants, to obtain solutions to combinatorial optimization problems with Boolean constraints, and to determine the susceptibility of a facility to unauthorized access through nullification of sensors in its protection system.
NASA Astrophysics Data System (ADS)
Ulenikov, O. N.; Gromova, O. V.; Bekhtereva, E. S.; Berezkin, K. B.; Kashirina, N. V.; Tan, T. L.; Sydow, C.; Maul, C.; Bauerecker, S.
2016-09-01
The highly accurate (experimental accuracy in line positions ~(1 - 3) ×10-4cm-1) FTIR ro-vibrational spectra of CH2=CD2 in the region of 600-1300 cm-1, where the fundamental bands ν10, ν7, ν4, ν8, ν3, and ν6 are located, were recorded and analyzed with the Hamiltonian model which takes into account resonance interactions between all six studied bands. About 12 200 ro-vibrational transitions belonging to these bands (that is considerably more than it was made in the preceding studies for the bands ν10, ν7, ν8, ν3 and ν6; transitions belonging to the ν4 band were assigned for the first time) were assigned in the experimental spectra with the maximum values of quantum numbers Jmax. / Kamax . equal to 31/20, 46/18, 33/11, 50/26, 44/20 and 42/21 for the bands ν10, ν7, ν4, ν8, ν3, and ν6, respectively. On that basis, a set of 133 vibrational, rotational, centrifugal distortion and resonance interaction parameters was obtained from the weighted fit. They reproduce values of 3920 initial "experimental" ro-vibrational energy levels (positions of about 12 200 experimentally recorded and assigned transitions) with the rms error drms = 2.3 ×10-4cm-1.
NASA Astrophysics Data System (ADS)
Srivastava, Saurabh; Sathyamurthy, N.
2012-12-01
The spin forbidden transition a1Δ → X3Σ- in CH- has been studied using the Breit-Pauli Hamiltonian for a large number of geometries. This transition acquires intensity through spin-orbit coupling with singlet and triplet Π states. The transition moment matrix including more than one singlet and triplet Π states was calculated at the multi-reference configuration interaction/aug-cc-pV6Z level of theory. The computed radiative lifetime of 5.63 s is in good agreement with the experimental (5.9 s) and other theoretical (6.14 s) results. Transition moment values of the spin allowed A3Π → X3Σ- transition have also been calculated at the same level of theory. Calculations show that the corresponding radiative lifetime is considerably low, 2.4 × 10-7 s. Complete basis set extrapolated potential energy curves for the ground state of CH and the ground state and six low lying excited states (a1Δ, b1Σ+, two 3Π, and two 1Π) of CH- are reported. These curves are then used to calculate the vibrational bound states for CH and CH-. The computed electron affinity of CH supports the electron affinity bounds reported by Okumura et al. [J. Chem. Phys. 85, 1971 (1986), 10.1063/1.451140].
Radioactive Waste Management Basis
Perkins, B K
2009-06-03
The purpose of this Radioactive Waste Management Basis is to describe the systematic approach for planning, executing, and evaluating the management of radioactive waste at LLNL. The implementation of this document will ensure that waste management activities at LLNL are conducted in compliance with the requirements of DOE Order 435.1, Radioactive Waste Management, and the Implementation Guide for DOE Manual 435.1-1, Radioactive Waste Management Manual. Technical justification is provided where methods for meeting the requirements of DOE Order 435.1 deviate from the DOE Manual 435.1-1 and Implementation Guide.
The Biological Basis of Learning and Individuality.
ERIC Educational Resources Information Center
Kandel, Eric R.; Hawkins, Robert D.
1992-01-01
Describes the biological basis of learning and individuality. Presents an overview of recent discoveries that suggest learning engages a simple set of rules that modify the strength of connection between neurons in the brain. The changes are cited as playing an important role in making each individual unique. (MCO)
The Emotional and Moral Basis of Rationality
ERIC Educational Resources Information Center
Boostrom, Robert
2013-01-01
This chapter explores the basis of rationality, arguing that critical thinking tends to be taught in schools as a set of skills because of the failure to recognize that choosing to think critically depends on the prior development of stable sentiments or moral habits that nourish a rational self. Primary among these stable sentiments are the…
NASA Astrophysics Data System (ADS)
Bourdelle, C.; Artaud, J. F.; Basiuk, V.; Bécoulet, M.; Brémond, S.; Bucalossi, J.; Bufferand, H.; Ciraolo, G.; Colas, L.; Corre, Y.; Courtois, X.; Decker, J.; Delpech, L.; Devynck, P.; Dif-Pradalier, G.; Doerner, R. P.; Douai, D.; Dumont, R.; Ekedahl, A.; Fedorczak, N.; Fenzi, C.; Firdaouss, M.; Garcia, J.; Ghendrih, P.; Gil, C.; Giruzzi, G.; Goniche, M.; Grisolia, C.; Grosman, A.; Guilhem, D.; Guirlet, R.; Gunn, J.; Hennequin, P.; Hillairet, J.; Hoang, T.; Imbeaux, F.; Ivanova-Stanik, I.; Joffrin, E.; Kallenbach, A.; Linke, J.; Loarer, T.; Lotte, P.; Maget, P.; Marandet, Y.; Mayoral, M. L.; Meyer, O.; Missirlian, M.; Mollard, P.; Monier-Garbet, P.; Moreau, P.; Nardon, E.; Pégourié, B.; Peysson, Y.; Sabot, R.; Saint-Laurent, F.; Schneider, M.; Travère, J. M.; Tsitrone, E.; Vartanian, S.; Vermare, L.; Yoshida, M.; Zagorski, R.; Contributors, JET
2015-06-01
With WEST (Tungsten Environment in Steady State Tokamak) (Bucalossi et al 2014 Fusion Eng. Des. 89 907-12), the Tore Supra facility and team expertise (Dumont et al 2014 Plasma Phys. Control. Fusion 56 075020) is used to pave the way towards ITER divertor procurement and operation. It consists in implementing a divertor configuration and installing ITER-like actively cooled tungsten monoblocks in the Tore Supra tokamak, taking full benefit of its unique long-pulse capability. WEST is a user facility platform, open to all ITER partners. This paper describes the physics basis of WEST: the estimated heat flux on the divertor target, the planned heating schemes, the expected behaviour of the L-H threshold and of the pedestal and the potential W sources. A series of operating scenarios has been modelled, showing that ITER-relevant heat fluxes on the divertor can be achieved in WEST long pulse H-mode plasmas.
Basis Selection for Wavelet Regression
NASA Technical Reports Server (NTRS)
Wheeler, Kevin R.; Lau, Sonie (Technical Monitor)
1998-01-01
A wavelet basis selection procedure is presented for wavelet regression. Both the basis and the threshold are selected using cross-validation. The method includes the capability of incorporating prior knowledge on the smoothness (or shape of the basis functions) into the basis selection procedure. The results of the method are demonstrated on sampled functions widely used in the wavelet regression literature. The results of the method are contrasted with other published methods.
Probabilistic Open Set Recognition
NASA Astrophysics Data System (ADS)
Jain, Lalit Prithviraj
support vector machines. Building from the success of statistical EVT based recognition methods such as PI-SVM and W-SVM on the open set problem, we present a new general supervised learning algorithm for multi-class classification and multi-class open set recognition called the Extreme Value Local Basis (EVLB). The design of this algorithm is motivated by the observation that extrema from known negative class distributions are the closest negative points to any positive sample during training, and thus should be used to define the parameters of a probabilistic decision model. In the EVLB, the kernel distribution for each positive training sample is estimated via an EVT distribution fit over the distances to the separating hyperplane between positive training sample and closest negative samples, with a subset of the overall positive training data retained to form a probabilistic decision boundary. Using this subset as a frame of reference, the probability of a sample at test time decreases as it moves away from the positive class. Possessing this property, the EVLB is well-suited to open set recognition problems where samples from unknown or novel classes are encountered at test. Our experimental evaluation shows that the EVLB provides a substantial improvement in scalability compared to standard radial basis function kernel machines, as well as P I-SVM and W-SVM, with improved accuracy in many cases. We evaluate our algorithm on open set variations of the standard visual learning benchmarks, as well as with an open subset of classes from Caltech 256 and ImageNet. Our experiments show that PI-SVM, WSVM and EVLB provide significant advances over the previous state-of-the-art solutions for the same tasks.
Advanced Fuel Cycle Cost Basis
D. E. Shropshire; K. A. Williams; W. B. Boore; J. D. Smith; B. W. Dixon; M. Dunzik-Gougar; R. D. Adams; D. Gombert
2007-04-01
This report, commissioned by the U.S. Department of Energy (DOE), provides a comprehensive set of cost data supporting a cost analysis for the relative economic comparison of options for use in the Advanced Fuel Cycle Initiative (AFCI) Program. The report describes the AFCI cost basis development process, reference information on AFCI cost modules, a procedure for estimating fuel cycle costs, economic evaluation guidelines, and a discussion on the integration of cost data into economic computer models. This report contains reference cost data for 26 cost modules—24 fuel cycle cost modules and 2 reactor modules. The cost modules were developed in the areas of natural uranium mining and milling, conversion, enrichment, depleted uranium disposition, fuel fabrication, interim spent fuel storage, reprocessing, waste conditioning, spent nuclear fuel (SNF) packaging, long-term monitored retrievable storage, near surface disposal of low-level waste (LLW), geologic repository and other disposal concepts, and transportation processes for nuclear fuel, LLW, SNF, and high-level waste.
Advanced Fuel Cycle Cost Basis
D. E. Shropshire; K. A. Williams; W. B. Boore; J. D. Smith; B. W. Dixon; M. Dunzik-Gougar; R. D. Adams; D. Gombert; E. Schneider
2008-03-01
This report, commissioned by the U.S. Department of Energy (DOE), provides a comprehensive set of cost data supporting a cost analysis for the relative economic comparison of options for use in the Advanced Fuel Cycle Initiative (AFCI) Program. The report describes the AFCI cost basis development process, reference information on AFCI cost modules, a procedure for estimating fuel cycle costs, economic evaluation guidelines, and a discussion on the integration of cost data into economic computer models. This report contains reference cost data for 25 cost modules—23 fuel cycle cost modules and 2 reactor modules. The cost modules were developed in the areas of natural uranium mining and milling, conversion, enrichment, depleted uranium disposition, fuel fabrication, interim spent fuel storage, reprocessing, waste conditioning, spent nuclear fuel (SNF) packaging, long-term monitored retrievable storage, near surface disposal of low-level waste (LLW), geologic repository and other disposal concepts, and transportation processes for nuclear fuel, LLW, SNF, transuranic, and high-level waste.
Advanced Fuel Cycle Cost Basis
D. E. Shropshire; K. A. Williams; W. B. Boore; J. D. Smith; B. W. Dixon; M. Dunzik-Gougar; R. D. Adams; D. Gombert; E. Schneider
2009-12-01
This report, commissioned by the U.S. Department of Energy (DOE), provides a comprehensive set of cost data supporting a cost analysis for the relative economic comparison of options for use in the Advanced Fuel Cycle Initiative (AFCI) Program. The report describes the AFCI cost basis development process, reference information on AFCI cost modules, a procedure for estimating fuel cycle costs, economic evaluation guidelines, and a discussion on the integration of cost data into economic computer models. This report contains reference cost data for 25 cost modules—23 fuel cycle cost modules and 2 reactor modules. The cost modules were developed in the areas of natural uranium mining and milling, conversion, enrichment, depleted uranium disposition, fuel fabrication, interim spent fuel storage, reprocessing, waste conditioning, spent nuclear fuel (SNF) packaging, long-term monitored retrievable storage, near surface disposal of low-level waste (LLW), geologic repository and other disposal concepts, and transportation processes for nuclear fuel, LLW, SNF, transuranic, and high-level waste.
[Basis of radiation protection].
Roth, J; Schweizer, P; Gückel, C
1996-06-29
After an introduction, three selected contributions to the 10th Course on Radiation Protection held at the University Hospital of Basel are presented. The principles of radiation protection and new Swiss legislation are discussed as the basis for radiological protection. Ways are proposed of reducing radiation exposure while optimizing the X-ray picture with a minimum dose to patient and personnel. Radiation effects from low doses. From the beginning, life on this planet has been exposed to ionizing radiation from natural sources. For about one century additional irradiation has reached us from man-made sources as well. In Switzerland the overall annual radiation exposure from ambient and man-made sources amounts to about 4 mSv. The terrestrial and cosmic radiation and natural radionuclids in the body cause about 1.17 mSv (29%). As much as 1.6 mSv (40%) results from exposure to radon and its progenies, primarily inside homes. Medical applications contribute approximately 1 mSv (26%) to the annual radiation exposure and releases from atomic weapons, nuclear facilities and miscellaneous industrial operations yield less than 0.12 mSv (< 5%) to the annual dose. Observations of detrimental radiation effects from intermediate to high doses are challenged by observations of biopositive adaptive responses and hormesis following low dose exposure. The important question, whether cellular adaptive response or hormesis could cause beneficial effects to the human organism that would outweigh the detrimental effects attributed to low radiation doses, remains to be resolved. Whether radiation exerts a detrimental, inhibitory, modifying or even beneficial effect is likely to result from identical molecular lesions but to depend upon their quantity, localization and time scale of initiation, as well as the specific responsiveness of the cellular systems involved. For matters of radiation protection the bionegative radiation effects are classified as deterministic effects or
47 CFR 4.1 - Scope, basis and purpose.
Code of Federal Regulations, 2013 CFR
2013-10-01
... 47 Telecommunication 1 2013-10-01 2013-10-01 false Scope, basis and purpose. 4.1 Section 4.1... and purpose. In this part, the Federal Communications Commission is setting forth requirements... communications infrastructures....
47 CFR 4.1 - Scope, basis and purpose.
Code of Federal Regulations, 2012 CFR
2012-10-01
... 47 Telecommunication 1 2012-10-01 2012-10-01 false Scope, basis and purpose. 4.1 Section 4.1... and purpose. In this part, the Federal Communications Commission is setting forth requirements... communications infrastructures....
47 CFR 4.1 - Scope, basis and purpose.
Code of Federal Regulations, 2011 CFR
2011-10-01
... 47 Telecommunication 1 2011-10-01 2011-10-01 false Scope, basis and purpose. 4.1 Section 4.1... and purpose. In this part, the Federal Communications Commission is setting forth requirements... communications infrastructures....
47 CFR 4.1 - Scope, basis and purpose.
Code of Federal Regulations, 2014 CFR
2014-10-01
... 47 Telecommunication 1 2014-10-01 2014-10-01 false Scope, basis and purpose. 4.1 Section 4.1... and purpose. In this part, the Federal Communications Commission is setting forth requirements... communications infrastructures....
42 CFR 457.700 - Basis, scope, and applicability.
Code of Federal Regulations, 2010 CFR
2010-10-01
... Strategic Planning, Reporting, and Evaluation § 457.700 Basis, scope, and applicability. (a) Statutory basis... strategic planning, reports, and program budgets; and (2) Section 2108 of the Act, which sets forth... strategic planning, monitoring, reporting and evaluation under title XXI. (c) Applicability....
47 CFR 4.1 - Scope, basis and purpose.
Code of Federal Regulations, 2010 CFR
2010-10-01
... 47 Telecommunication 1 2010-10-01 2010-10-01 false Scope, basis and purpose. 4.1 Section 4.1 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL DISRUPTIONS TO COMMUNICATIONS General § 4.1 Scope, basis and purpose. In this part, the Federal Communications Commission is setting forth...
28 CFR 36.203 - Integrated settings.
Code of Federal Regulations, 2013 CFR
2013-07-01
... 28 Judicial Administration 1 2013-07-01 2013-07-01 false Integrated settings. 36.203 Section 36.203 Judicial Administration DEPARTMENT OF JUSTICE NONDISCRIMINATION ON THE BASIS OF DISABILITY BY PUBLIC ACCOMMODATIONS AND IN COMMERCIAL FACILITIES General Requirements § 36.203 Integrated settings....
45 CFR 605.34 - Educational setting.
Code of Federal Regulations, 2010 CFR
2010-10-01
... ON THE BASIS OF HANDICAP IN PROGRAMS OR ACTIVITIES RECEIVING FEDERAL FINANCIAL ASSISTANCE Preschool, Elementary, and Secondary Education § 605.34 Educational setting. (a) Academic setting. A recipient to which this subpart applies shall educate, or shall provide for the education of, each qualified...
UpSet: Visualization of Intersecting Sets
Lex, Alexander; Gehlenborg, Nils; Strobelt, Hendrik; Vuillemot, Romain; Pfister, Hanspeter
2016-01-01
Understanding relationships between sets is an important analysis task that has received widespread attention in the visualization community. The major challenge in this context is the combinatorial explosion of the number of set intersections if the number of sets exceeds a trivial threshold. In this paper we introduce UpSet, a novel visualization technique for the quantitative analysis of sets, their intersections, and aggregates of intersections. UpSet is focused on creating task-driven aggregates, communicating the size and properties of aggregates and intersections, and a duality between the visualization of the elements in a dataset and their set membership. UpSet visualizes set intersections in a matrix layout and introduces aggregates based on groupings and queries. The matrix layout enables the effective representation of associated data, such as the number of elements in the aggregates and intersections, as well as additional summary statistics derived from subset or element attributes. Sorting according to various measures enables a task-driven analysis of relevant intersections and aggregates. The elements represented in the sets and their associated attributes are visualized in a separate view. Queries based on containment in specific intersections, aggregates or driven by attribute filters are propagated between both views. We also introduce several advanced visual encodings and interaction methods to overcome the problems of varying scales and to address scalability. UpSet is web-based and open source. We demonstrate its general utility in multiple use cases from various domains. PMID:26356912
Biological basis for protection of the environment.
Larsson, C-M
2012-01-01
The approach to protection of the environment may vary considerably depending on ethical basis, methodological approach, and identification of endpoints and protective targets. The International Commission on Radiological Protection (ICRP) reviewed these issues in Publication 91, 'A framework for assessing the impact of ionising radiation on non-human species', published in 2003. At the same time, ICRP proposed that a possible future ICRP system addressing environmental assessment and protection would focus on biota, that the system should be effect-based so that any reasoning about adequate protection would be derived from firm understanding of harm at different exposure levels, and that the system should be based on data sets for Reference Animals and Plants. ICRP has thus chosen to approach environmental protection on the basis of biology, and further developed the approach in Publications 103, 108 and 114. This paper explores the biological basis for the ICRP system of environmental protection from the viewpoints of: the effects endpoints of concern; the hierarchy of biological organisation; adequate and appropriate protective targets; and the derivation of benchmark dose (rates) to guide protective efforts.
Neurocybernetic basis of semantic processes.
Restian, A
1984-11-01
Although semantics cannot be reduced to neurophysiology, it must have however a certain neurophysiologic basis and this paper deals with, that neurophysiologic basis which, in fact, has a neurocybernetic basis. The paper first approaches the relations between information and signification and their part within the nervous system's work. Then, it analyses semantic function discoverying neurocybernetic mechanisms which can be proper not only to the conventional signs but also to the objects and phenomena which in turn can play the sign's part. Finally, semantic levels of the nervous system, beginning with the most elementary level of unity, as letters are, and up to the level of the highest ideas and concepts the brain is working with, are described.
GASB's Basis of Accounting Project.
ERIC Educational Resources Information Center
Kovlak, Daniel L.
1986-01-01
In July 1984, the Governmental Accounting Standards Board began its "Measurement Focus/Basis of Accounting" project, which addresses measurement issues and revenue and expenditure recognition problems involving governmental funds. This article explains the project's background, alternatives discussed by the board, and tentative conclusions and…
Reflection Relations and Fermionic Basis
NASA Astrophysics Data System (ADS)
Negro, S.; Smirnov, F.
2013-12-01
There are two approaches to computing the one-point functions for sine-Gordon model in infinite volume. One is based on the use of the reflection relations, this is a bootstrap type procedure. Another is based on using the fermionic basis which originated in the study of lattice model. We show that the two procedures are deeply interrelated.
ERIC Educational Resources Information Center
Weinberg, Robert A.
1983-01-01
Discusses the molecular basis of cancer, focusing on genetics of the disease. Indicates that human cancers are initiated by oncogenes (altered versions of normal genes) and that in one case the critical alteration is a single point mutation that changes one amino acid in the protein encoded by the gene. (JN)
Grobner Basis Representations of Sudoku
ERIC Educational Resources Information Center
Taalman, Laura; Arnold, Elizabeth; Lucas, Stephen
2010-01-01
This paper uses Grobner bases to explore the inherent structure of Sudoku puzzles and boards. In particular, we develop three different ways of representing the constraints of Sudoku puzzles with a system of polynomial equations. In one case, we explicitly show how a Grobner basis can be used to obtain a more meaningful representation of the…
Differential Forms Basis Functions for Better Conditioned Integral Equations
Fasenfest, B; White, D; Stowell, M; Rieben, R; Sharpe, R; Madsen, N; Rockway, J D; Champagne, N J; Jandhyala, V; Pingenot, J
2005-01-13
Differential forms offer a convenient way to classify physical quantities and set up computational problems. By observing the dimensionality and type of derivatives (divergence,curl,gradient) applied to a quantity, an appropriate differential form can be chosen for that quantity. To use these differential forms in a simulation, the forms must be discretized using basis functions. The 0-form through 2-form basis functions are formed for surfaces. Twisted 1-form and 2-form bases will be presented in this paper. Twisted 1-form (1-forms) basis functions ({Lambda}) are divergence-conforming edge basis functions with units m{sup -1}. They are appropriate for representing vector quantities with continuous normal components, and they belong to the same function space as the commonly used RWG bases [1]. They are used here to formulate the frequency-domain EFIE with Galerkin testing. The 2-form basis functions (f) are scalar basis functions with units m{sup -2} and with no enforced continuity between elements. At lowest order, the 2-form basis functions are similar to pulse basis functions. They are used here to formulate an electrostatic integral equation. It should be noted that the derivative of an n-form differential form basis function is an (n+1)-form, i.e. the derivative of a 1-form basis function is a 2-form. Because the basis functions are constructed such that they have spatial units, the spatial units are removed from the degrees of freedom, leading to a better-conditioned system matrix. In this conference paper, we look at the performance of these differential forms and bases by examining the conditioning of matrix systems for electrostatics and the EFIE. The meshes used were refined across the object to consider the behavior of these basis transforms for elements of different sizes.
Perceptual basis for reactive teleoperation.
Park, Y. S.; Ewing, T. F.; Boyle, J. M.; Yule, T. J.
2001-08-28
To enhance task performance in partially structured environment, enhancement of teleoperation was proposed by introducing autonomous behaviors. Such autonomy is implemented based on reactive robotic architecture, where reactive motor agents that directly couples sensory inputs and motor actions become the building blocks. To this end, presented in this paper is a perceptual basis for the motor agents. The perceptual basis consists of perceptual agents that extracts environmental information from a structured light vision system and provide action oriented perception for the corresponding motor agents. Rather than performing general scene reconstruction, a perceptual agent directly provides the motion reference for the motor behavior. Various sensory mechanisms--sensor fission, fusion, and fashion--becomes basic building blocks of the perception process. Since perception is a process deeply intertwined with the motor actions, active perception may also incorporate motor behaviors as an integral perceptual process.
Hanford Generic Interim Safety Basis
Lavender, J.C.
1994-09-09
The purpose of this document is to identify WHC programs and requirements that are an integral part of the authorization basis for nuclear facilities that are generic to all WHC-managed facilities. The purpose of these programs is to implement the DOE Orders, as WHC becomes contractually obligated to implement them. The Hanford Generic ISB focuses on the institutional controls and safety requirements identified in DOE Order 5480.23, Nuclear Safety Analysis Reports.
Detection of Gaseous Plumes using Basis Vectors
Chilton, Lawrence; Walsh, Stephen
2009-05-01
Detecting and identifying weak gaseous plumes using thermal imaging data is complicated by many factors. There are several methods currently being used to detect plumes. They can be grouped into two categories: those that use a chemical spectral library and those that don’t. The approaches that use chemical libraries include least squares methods and physics-based approaches. They are "optimal" only if the plume chemical is actually in the search set but risk missing chemicals not in the library. The methods that don’t use a chemical spectral library are based on a statistical or data analytical transformation applied to the data. These include principle components, independent components, entropy, Fourier transform, and others. These methods do not explicitly take advantage of the physics of the signal formulation process and therefore don’t exploit all available information in the data. This paper presents initial results of employing basis vectors as a tool for plume detection. It describes the standard generalized least squares approach using gas spectra, presents the detection approach using basis vectors, and compares detection images resulting from applying both methods to synthetic hyperspectral images.
NASA Astrophysics Data System (ADS)
Dubois, P. F.
1990-10-01
We have made major changes to the computer science aspects of our laser fusion simulation program LASNEX. LASNEX is now using the Basis system, a FORTRAN development system developed over the last six years at Lawrence Livermore National Laboratory. This has given users greatly increased power and flexibility. We have eliminated all non-standard usage and macros, enabling us to begin the port of LASNEX to workstations. At the same time, we have completely redone the system used to maintain the source and create new versions of LASNEX, resulting in major gains in capability and productivity.
Dubois, P.F.
1990-10-26
We have made major changes to the computer science aspects of our laser fusion simulation program LASNEX. LASNEX is now using the Basis system, a Fortran development system developed over the last six years at Lawrence Livermore National Laboratory. This has given users greatly increased power and flexibility. We have eliminated all non-standard usage and macros, enabling us to begin the port of LASNEX to workstations. At the same time, we have completely redone the system used to maintain the source and create new versions of LASNEX, resulting in major gains in capability and productivity. 5 refs.
Value basis for conservation policy
Leiss, W.
1981-01-01
This paper is a case study in attempting to apply a particular value (caring) to the domain of social policy, specifically resource conservation policy. The argument is that our consumer society erodes the social basis for the development by individuals of a sense of well-being and personal identity, and that a conservation ethic based on the concept of caring could provide a foundation in practical morality and public policy for a viable sense of well-being. Conservation, then, goes beyond eliminating wasteful consumption to encompass a public commitment that can further economic and social goals. 11 references.
OSR encapsulation basis -- 100-KW
Meichle, R.H.
1995-01-27
The purpose of this report is to provide the basis for a change in the Operations Safety Requirement (OSR) encapsulated fuel storage requirements in the 105 KW fuel storage basin which will permit the handling and storing of encapsulated fuel in canisters which no longer have a water-free space in the top of the canister. The scope of this report is limited to providing the change from the perspective of the safety envelope (bases) of the Safety Analysis Report (SAR) and Operations Safety Requirements (OSR). It does not change the encapsulation process itself.
42 CFR 402.1 - Basis and scope.
Code of Federal Regulations, 2014 CFR
2014-10-01
... section; and (2) Sets forth the appeal rights of persons subject to penalties, assessments, or exclusion...) and 1842(j)(2)—Any person that knowingly and willfully, and on a repeated basis, bills for a clinical... willfully presents, or causes to be presented, a bill or request for payment for an intraocular...
40 CFR 35.162 - Basis for allotment.
Code of Federal Regulations, 2010 CFR
2010-07-01
... STATE AND LOCAL ASSISTANCE Environmental Program Grants Water Pollution Control (section 106) § 35.162 Basis for allotment. (a) Allotments. Each fiscal year funds appropriated for Water Pollution Control... for States under the Water Pollution Control grant program will be set aside for allotment to...
40 CFR 35.162 - Basis for allotment.
Code of Federal Regulations, 2011 CFR
2011-07-01
... STATE AND LOCAL ASSISTANCE Environmental Program Grants Water Pollution Control (section 106) § 35.162 Basis for allotment. (a) Allotments. Each fiscal year funds appropriated for Water Pollution Control... for States under the Water Pollution Control grant program will be set aside for allotment to...
40 CFR 35.162 - Basis for allotment.
Code of Federal Regulations, 2013 CFR
2013-07-01
... STATE AND LOCAL ASSISTANCE Environmental Program Grants Water Pollution Control (section 106) § 35.162 Basis for allotment. (a) Allotments. Each fiscal year funds appropriated for Water Pollution Control... for States under the Water Pollution Control grant program will be set aside for allotment to...
40 CFR 35.162 - Basis for allotment.
Code of Federal Regulations, 2012 CFR
2012-07-01
... STATE AND LOCAL ASSISTANCE Environmental Program Grants Water Pollution Control (section 106) § 35.162 Basis for allotment. (a) Allotments. Each fiscal year funds appropriated for Water Pollution Control... for States under the Water Pollution Control grant program will be set aside for allotment to...
40 CFR 35.162 - Basis for allotment.
Code of Federal Regulations, 2014 CFR
2014-07-01
... STATE AND LOCAL ASSISTANCE Environmental Program Grants Water Pollution Control (section 106) § 35.162 Basis for allotment. (a) Allotments. Each fiscal year funds appropriated for Water Pollution Control... for States under the Water Pollution Control grant program will be set aside for allotment to...
45 CFR 146.101 - Basis and scope.
Code of Federal Regulations, 2011 CFR
2011-10-01
... 45 Public Welfare 1 2011-10-01 2011-10-01 false Basis and scope. 146.101 Section 146.101 Public Welfare DEPARTMENT OF HEALTH AND HUMAN SERVICES REQUIREMENTS RELATING TO HEALTH CARE ACCESS REQUIREMENTS... participants and beneficiaries based on genetic information. (2) Subpart C. Subpart C of this part sets...
45 CFR 146.101 - Basis and scope.
Code of Federal Regulations, 2013 CFR
2013-10-01
... 45 Public Welfare 1 2013-10-01 2013-10-01 false Basis and scope. 146.101 Section 146.101 Public Welfare DEPARTMENT OF HEALTH AND HUMAN SERVICES REQUIREMENTS RELATING TO HEALTH CARE ACCESS REQUIREMENTS... participants and beneficiaries based on genetic information. (2) Subpart C. Subpart C of this part sets...
45 CFR 146.101 - Basis and scope.
Code of Federal Regulations, 2012 CFR
2012-10-01
... 45 Public Welfare 1 2012-10-01 2012-10-01 false Basis and scope. 146.101 Section 146.101 Public Welfare DEPARTMENT OF HEALTH AND HUMAN SERVICES REQUIREMENTS RELATING TO HEALTH CARE ACCESS REQUIREMENTS... participants and beneficiaries based on genetic information. (2) Subpart C. Subpart C of this part sets...
Precision of a radial basis function neural network tracking method
NASA Technical Reports Server (NTRS)
Hanan, J.; Zhou, H.; Chao, T. H.
2003-01-01
The precision of a radial basis function (RBF) neural network based tracking method has been assessed against real targets. Precision was assessed against traditionally measured frame-by-frame measurements from the recorded data set. The results show the potential limit for the technique and reveal intricacies associated with empirical data not necessarily observed in simulations.
42 CFR 493.1 - Basis and scope.
Code of Federal Regulations, 2010 CFR
2010-10-01
... specimens under the Clinical Laboratory Improvement Amendments of 1988 (CLIA). It implements sections 1861... AND CERTIFICATION LABORATORY REQUIREMENTS General Provisions § 493.1 Basis and scope. This part sets... under “laboratory” in § 493.2 of this part. This part also applies to laboratories seeking payment...
NASA Astrophysics Data System (ADS)
Teutsch, Jason
2007-01-01
It is possible to enumerate all computer programs. In particular, for every partial computable function, there is a shortest program which computes that function. f-MIN is the set of indices for shortest programs. In 1972, Meyer showed that f-MIN is Turing equivalent to 0'', the halting set with halting set oracle. This paper generalizes the notion of shortest programs, and we use various measures from computability theory to describe the complexity of the resulting "spectral sets." We show that under certain Godel numberings, the spectral sets are exactly the canonical sets 0', 0'', 0''', ... up to Turing equivalence. This is probably not true in general, however we show that spectral sets always contain some useful information. We show that immunity, or "thinness" is a useful characteristic for distinguishing between spectral sets. In the final chapter, we construct a set which neither contains nor is disjoint from any infinite arithmetic set, yet it is 0-majorized and contains a natural spectral set. Thus a pathological set becomes a bit more friendly. Finally, a number of interesting open problems are left for the inspired reader.
ERIC Educational Resources Information Center
Baker, Mark; Beltran, Jane; Buell, Jason; Conrey, Brian; Davis, Tom; Donaldson, Brianna; Detorre-Ozeki, Jeanne; Dibble, Leila; Freeman, Tom; Hammie, Robert; Montgomery, Julie; Pickford, Avery; Wong, Justine
2013-01-01
Sets in the game "Set" are lines in a certain four-dimensional space. Here we introduce planes into the game, leading to interesting mathematical questions, some of which we solve, and to a wonderful variation on the game "Set," in which every tableau of nine cards must contain at least one configuration for a player to pick up.
Approaching the complete-basis limit with a truncated many-body expansion.
Richard, Ryan M; Lao, Ka Un; Herbert, John M
2013-12-14
High-accuracy electronic structure calculations with correlated wave functions demand the use of large basis sets and complete-basis extrapolation, but the accuracy of fragment-based quantum chemistry methods has most often been evaluated using double-ζ basis sets, with errors evaluated relative to a supersystem calculation using the same basis set. Here, we examine the convergence towards the basis-set limit of two- and three-body expansions of the energy, for water clusters and ion-water clusters, focusing on calculations at the level of second-order Møller-Plesset perturbation theory (MP2). Several different corrections for basis-set superposition error (BSSE), each consistent with a truncated many-body expansion, are examined as well. We present a careful analysis of how the interplay of errors (from all sources) influences the accuracy of the results. We conclude that fragment-based methods often benefit from error cancellation wherein BSSE offsets both incompleteness of the basis set as well as higher-order many-body effects that are neglected in a truncated many-body expansion. An n-body counterpoise correction facilitates smooth extrapolation to the MP2 basis-set limit, and at n = 3 affords accurate results while requiring calculations in subsystems no larger than trimers. PMID:24329051
Approaching the complete-basis limit with a truncated many-body expansion
Richard, Ryan M.; Lao, Ka Un; Herbert, John M.
2013-12-14
High-accuracy electronic structure calculations with correlated wave functions demand the use of large basis sets and complete-basis extrapolation, but the accuracy of fragment-based quantum chemistry methods has most often been evaluated using double-ζ basis sets, with errors evaluated relative to a supersystem calculation using the same basis set. Here, we examine the convergence towards the basis-set limit of two- and three-body expansions of the energy, for water clusters and ion–water clusters, focusing on calculations at the level of second-order Møller-Plesset perturbation theory (MP2). Several different corrections for basis-set superposition error (BSSE), each consistent with a truncated many-body expansion, are examined as well. We present a careful analysis of how the interplay of errors (from all sources) influences the accuracy of the results. We conclude that fragment-based methods often benefit from error cancellation wherein BSSE offsets both incompleteness of the basis set as well as higher-order many-body effects that are neglected in a truncated many-body expansion. An n-body counterpoise correction facilitates smooth extrapolation to the MP2 basis-set limit, and at n = 3 affords accurate results while requiring calculations in subsystems no larger than trimers.
The neurological basis of occupation.
Gutman, Sharon A; Schindler, Victoria P
2007-01-01
The purpose of the present paper was to survey the literature about the neurological basis of human activity and its relationship to occupation and health. Activities related to neurological function were organized into three categories: those that activate the brain's reward system; those that promote the relaxation response; and those that preserve cognitive function into old age. The results from the literature review correlating neurological evidence and activities showed that purposeful and meaningful activities could counter the effects of stress-related diseases and reduce the risk for dementia. Specifically, it was found that music, drawing, meditation, reading, arts and crafts, and home repairs, for example, can stimulate the neurogical system and enhance health and well-being, Prospective research studies are needed to examine the effects of purposeful activities on reducing stress and slowing the rate of cognitive decline.
Internal dosimetry technical basis manual
Not Available
1990-12-20
The internal dosimetry program at the Savannah River Site (SRS) consists of radiation protection programs and activities used to detect and evaluate intakes of radioactive material by radiation workers. Examples of such programs are: air monitoring; surface contamination monitoring; personal contamination surveys; radiobioassay; and dose assessment. The objectives of the internal dosimetry program are to demonstrate that the workplace is under control and that workers are not being exposed to radioactive material, and to detect and assess inadvertent intakes in the workplace. The Savannah River Site Internal Dosimetry Technical Basis Manual (TBM) is intended to provide a technical and philosophical discussion of the radiobioassay and dose assessment aspects of the internal dosimetry program. Detailed information on air, surface, and personal contamination surveillance programs is not given in this manual except for how these programs interface with routine and special bioassay programs.
Molecular Basis of Cardiac Myxomas
Singhal, Pooja; Luk, Adriana; Rao, Vivek; Butany, Jagdish
2014-01-01
Cardiac tumors are rare, and of these, primary cardiac tumors are even rarer. Metastatic cardiac tumors are about 100 times more common than the primary tumors. About 90% of primary cardiac tumors are benign, and of these the most common are cardiac myxomas. Approximately 12% of primary cardiac tumors are completely asymptomatic while others present with one or more signs and symptoms of the classical triad of hemodynamic changes due to intracardiac obstruction, embolism and nonspecific constitutional symptoms. Echocardiography is highly sensitive and specific in detecting cardiac tumors. Other helpful investigations are chest X-rays, magnetic resonance imaging and computerized tomography scan. Surgical excision is the treatment of choice for primary cardiac tumors and is usually associated with a good prognosis. This review article will focus on the general features of benign cardiac tumors with an emphasis on cardiac myxomas and their molecular basis. PMID:24447924
The Chemical Basis of Pharmacology
2010-01-01
Molecular biology now dominates pharmacology so thoroughly that it is difficult to recall that only a generation ago the field was very different. To understand drug action today, we characterize the targets through which they act and new drug leads are discovered on the basis of target structure and function. Until the mid-1980s the information often flowed in reverse: investigators began with organic molecules and sought targets, relating receptors not by sequence or structure but by their ligands. Recently, investigators have returned to this chemical view of biology, bringing to it systematic and quantitative methods of relating targets by their ligands. This has allowed the discovery of new targets for established drugs, suggested the bases for their side effects, and predicted the molecular targets underlying phenotypic screens. The bases for these new methods, some of their successes and liabilities, and new opportunities for their use are described. PMID:21058655
The neurological basis of occupation.
Gutman, Sharon A; Schindler, Victoria P
2007-01-01
The purpose of the present paper was to survey the literature about the neurological basis of human activity and its relationship to occupation and health. Activities related to neurological function were organized into three categories: those that activate the brain's reward system; those that promote the relaxation response; and those that preserve cognitive function into old age. The results from the literature review correlating neurological evidence and activities showed that purposeful and meaningful activities could counter the effects of stress-related diseases and reduce the risk for dementia. Specifically, it was found that music, drawing, meditation, reading, arts and crafts, and home repairs, for example, can stimulate the neurogical system and enhance health and well-being, Prospective research studies are needed to examine the effects of purposeful activities on reducing stress and slowing the rate of cognitive decline. PMID:17623380
Set point calculations for RAPID project
HICKMAN, G.L.
1999-10-18
The Respond and Pump in Days (RAPID) project was initiated to pump part of the contents of tank 241-SY-101 into tank 241-SY-102. This document establishes the basis for all set points and ranges used in the RAPID project.
7 CFR 15b.23 - Educational setting.
Code of Federal Regulations, 2013 CFR
2013-01-01
... 7 Agriculture 1 2013-01-01 2013-01-01 false Educational setting. 15b.23 Section 15b.23 Agriculture Office of the Secretary of Agriculture NONDISCRIMINATION ON THE BASIS OF HANDICAP IN PROGRAMS OR... handicapped person. A recipient shall place a handicapped person in the regular educational...
7 CFR 15b.23 - Educational setting.
Code of Federal Regulations, 2010 CFR
2010-01-01
... 7 Agriculture 1 2010-01-01 2010-01-01 false Educational setting. 15b.23 Section 15b.23 Agriculture Office of the Secretary of Agriculture NONDISCRIMINATION ON THE BASIS OF HANDICAP IN PROGRAMS OR... handicapped person. A recipient shall place a handicapped person in the regular educational...
Acronical Risings and Settings
NASA Astrophysics Data System (ADS)
Hockey, Thomas A.
2012-01-01
A concept found in historical primary sources, and useful in contemporary historiography, is the acronical rising and setting of stars (or planets). Topocentric terms, they provide information about a star's relationship to the Sun and thus its visibility in the sky. Yet there remains ambiguity as to what these two phrases actually mean. "Acronical” is said to have come from the Greek akros ("point,” "summit,” or "extremity") and nux ("night"). While all sources agree that the word is originally Greek, there are alternate etymologies for it. A more serious difficulty with acronical rising and setting is that there are two competing definitions. One I call the Poetical Definition. Acronical rising (or setting) is one of the three Poetical Risings (or Settings) known to classicists. (The other two are cosmical rising/setting, discussed below, and the more familiar helical rising/setting.) The term "poetical" refers to these words use in classical poetry, e. g., that of Columella, Hesiod, Ovid, Pliny the Younger, and Virgil. The Poetical Definition of "acronical” usually is meant in this context. The Poetical Definition of "acronical” is as follows: When a star rises as the Sun sets, it rises acronically. When a star sets as the Sun sets, it sets acronically. In contrast with the Poetical Definition, there also is what I call the Astronomical Definition. The Astronomical Definition is somewhat more likely to appear in astronomical, mathematical, or navigational works. When the Astronomical Definition is recorded in dictionaries, it is often with the protasis "In astronomy, . . . ." The Astronomical Definition of "acronical” is as follows: When a star rises as the Sun sets, it rises acronically. When a star sets as the Sun rises, it sets acronically. I will attempt to sort this all out in my talk.
ERIC Educational Resources Information Center
Muijs, Daniel; Dunne, Mairead
2010-01-01
Background: Grouping students into classes by ability on a subject-by-subject basis, also known as setting, is a common practice in many educational systems. An important issue is therefore the way in which setting decisions are made. While educators and policy-makers favouring setting claim that ability or achievement is the sole criterion used,…
Norovirus in Healthcare Settings
... Guideline for Isolation Precautions: Preventing Transmission of Infectious Agents in Healthcare Settings Occupational Safety and Health Administration (OSHA) Fact Sheet on Noroviruses [PDF - 61 ...
Reid, David D.
2009-07-06
A key postulate of the causal set program is that this discrete partial order offers a sufficiently rich structure to make it a viable model of spacetime for quantum gravity. If the deep structure of spacetime is that of a causal set, then the correspondence principle (with the spacetimes of general relativity) must be obeyed. Therefore, one of the requirements of this program is to establish that the causal set structure is in fact, not just in principle, fully consistent with our macroscopic notion of spacetime as a Lorentzian manifold. An important component of any such 'manifold test' is the ability to find embeddings of causal sets into Lorentzian manifolds.
Structural basis of metal hypersensitivity
Wang, Yang
2014-01-01
Metal hypersensitivity is a common immune disorder. Human immune systems mount the allergic attacks on metal ions through skin contacts, lung inhalation and metal-containing artificial body implants. The consequences can be simple annoyances to life-threatening systemic illness. Allergic hyper-reactivities to nickel (Ni) and beryllium (Be) are the best-studied human metal hypersensitivities. Ni-contact dermatitis affects 10 % of the human population, whereas Be compounds are the culprits of chronic Be disease (CBD). αβ T cells (T cells) play a crucial role in these hypersensitivity reactions. Metal ions work as haptens and bind to the surface of major histocompatibility complex (MHC) and peptide complex. This modifies the binding surface of MHC and triggers the immune response of T cells. Metal-specific αβ T cell receptors (TCRs) are usually MHC restricted, especially MHC class II (MHCII) restricted. Numerous models have been proposed, yet the mechanisms and molecular basis of metal hypersensitivity remain elusive. Recently, we determined the crystal structures of the Ni and Be presenting human MHCII molecules, HLA-DR52c (DRA*0101, DRB3*0301) and HLA-DP2 (DPA1*0103, DPB1*0201). These structures revealed unusual features of MHCII molecules and shed light on how metal ions are recognized by T cells. PMID:22983897
Structural basis of spectrin elasticity
Shen, B.W.; Stevens, F.J.; Luthi, U.; Goldin, S.B.
1991-10-17
A new model of human erythrocyte {alpha}-spectrin is proposed. The secondary structure of human erythrocyte {alpha}-spectrin and its folding into a condensed structure that can convert reversibly in situ, into an elongated configuration is predicted from its deduced protein sequence. Results from conformational and amphipathicity analyses suggest that {alpha}-spectrin consists mainly of short amphipathicity helices interconnected by flexible turns and/or coils. The distribution of charges and amphipathicity of the helices can facilitate their folding into stable domains of 4 and 3 helices surrounding a hydrophobic core. The association between adjacent four- and three-helix domains further organize them into recurring seven-helix motifs that might constitute the basic structural units of the extended {alpha}-spectrin. The elongated spectrin molecule packs, in a sinusoidal fashion, through interactions between neighboring motifs into a compact structure. We suggest that the reversible extension and contraction of this sigmoidally packed structure is the molecular basis of the mechanism by which spectrin contributes to the elasticity of the red cell membrane.
Structural basis for selectin mechanochemistry.
Springer, Timothy A
2009-01-01
Selectins are adhesion molecules that resist large tensile forces applied by hydrodynamic forces to leukocytes binding to vessel walls. In crystals, the liganded (high-affinity) and unliganded (low-affinity) conformations differ in orientation between their tandem lectin and EGF domains. I examine how tensile force exerted on a selectin-ligand complex in vivo could favor the more extended, high-affinity conformation. Allostery is transmitted from the EGF-lectin domain interface to the ligand-binding interface on the lectin domain, 30 A away. Trp-1 of the lectin domain and the long axis of the EGF domain form an L-shaped prybar that is welded together by hydrogen bonds to the Trp-1 alpha-amino group. Pivoting of the prybar induced by force demolishes an interface between the Trp-1 side chain and the lectin domain at a switch1 region. These changes are transmitted by rigid body movement of the switch2 region to rearrangements in the switch3 region at the ligand binding site. Another switch region corresponds to a single residue in the EGF domain with large effects on ligand binding and rolling adhesion. Allostery in selectins, and the alignment of tensile force on a selectin-ligand complex with the transition pathway for conformational change, explain much of the structural basis for selectin mechanochemistry.
The autoimmune basis of narcolepsy.
Mahlios, Josh; De la Herrán-Arita, Alberto K; Mignot, Emmanuel
2013-10-01
Narcolepsy is a neurological disorder characterized by excessive daytime sleepiness, cataplexy, hypnagonic hallucinations, sleep paralysis, and disturbed nocturnal sleep patterns. Narcolepsy is caused by the loss of hypocretin (orexin)-producing neurons in the lateral hypothalamus. Evidence, such as a strong association with HLA DQB1*06:02, strongly suggests an autoimmune basis targeting hypocretin neurons. Genome-wide association studies have strengthened the association between narcolepsy and immune system gene polymorphisms, including the identification of polymorphisms in the T cell receptor alpha locus, TNFSF4 (also called OX40L), Cathepsin H (CTSH) the purinergic receptor P2RY11, and the DNA methyltransferase DNMT1. Recently, attention has been raised regarding a spike in cases of childhood narcolepsy in 2010 following the 2009 H1N1 pandemic (pH1N1) in China and vaccination with Pandemrix, an adjuvanted H1N1 vaccine that was used in Europe. How the immune system may be involved in disease initiation and/or progression remains a challenge to researchers. Potential immunological pathways that could lead to the specific elimination of hypocretin producing neurons include molecular mimicry or bystander activation, and are likely a combination of genetic and environmental factors, such as upper airway infections. PMID:23725858
NASA Astrophysics Data System (ADS)
Gehrels, N.; Teegarden, B.; Barbier, L.; Cline, T.; Parsons, A.; Tueller, J.; Barthelmy, S.; Palmer, D.; Krizmanic, J.; Fenimore, E.; Fishman, G.; Kouveliotou, C.; Hurley, K.; Paciesas, W.; van Paradijs, J.; Woosley, S.; Leventhal, M.; McCammon, D.; Sanders, W.; Schaefer, B.
1996-08-01
We are studying a gamma-ray burst mission concept called the Burst ArcSecond Imaging and Spectroscopy (BASIS) as part of NASA's New Mission Concepts for Astrophysics program. The scientific objectives are to accurately locate bursts, determine their distance scale, and measure the physical characteristics of the emission region. Arcsecond burst positions (angular resolution ~30 arcsec, source positions ~3 arcsec for >10-6 erg/cm2 bursts) would be obtained for ~100 bursts per year using the 10-200 keV emission. This would allow the first deep, unconfused counterpart searches at other wavelengths. The key technological breakthrough that makes such measurements possible is the development of CdZnTe room-temperature semiconductor detectors with fine (~100 micron) spatial resolution. Fine spectroscopy would be obtained between 0.2 and 200 keV. The 0.2 keV threshold would allow the first measurements of absorption in our Galaxy and possible host galaxies, constraining the distance scale and host environment.
The tensor properties of energy gradients within a non-orthogonal basis
NASA Astrophysics Data System (ADS)
White, Christopher A.; Maslen, Paul; Lee, Michael S.; Head-Gordon, Martin
1997-09-01
The application of standard minimization techniques to electronic structure theory calculations often requires the formation of an electronic energy gradient. The tensor nature of the electronic gradient, while implicitly treated within an orthogonal basis set, manifests itself explicitly in a non-orthogonal basis set. We apply simple tensor theory to define the electronic gradient in an arbitrary reference frame using the energy minimization method of Li, Nunes and Vanderbilt in a non-orthogonal basis as a concrete example. The minimal basis HeH + energy surface is used to portray the strong effect of consistently accounting for these tensor properties versus neglecting them.
The genetic basis of cognition.
Flint, J
1999-11-01
The molecular characterization of single-gene disorders or chromosomal abnormalities that result in a cognitive abnormality (predominantly mental retardation) and of the genetic variants responsible for variation in intellectual abilities (such as IQ, language impairment and dyslexia) is expected to provide new insights into the biology of human cognitive processes. To date this hope has not been realized. Success in finding mutations that give rise to mental retardation has not been matched by advances in our understanding of how genes influence cognition. In contrast, the use of engineered mutations in mice to study models of learning and memory has cast new light on the molecular basis of memory. A comparison of studies of human and mouse mutations indicates the limitations of current genetic approaches to the understanding of human cognition. It is essential to interpret a mutation's effect within a well-characterized neural system; mutations can be used to define gene function only when the mutation has an effect on a system whose constituents form a serial causal chain, such as the molecular components of a signal transduction pathway. Typically, however, genetic mutations with a cognitive and behavioural phenotype are characterized by specific effects on different systems whose inter-relationships are unknown. Genetic approaches are currently limited to exploring neuronal function; it is not yet clear whether they will throw light on how neuronal connections give rise to cognitive processes. We need a much greater integration of different levels of understanding of cognition in order to exploit the genetic discoveries. In short, a rapprochement between molecular and systems neuroscience is required.
Hayami, Masao; Seino, Junji; Nakai, Hiromi
2014-07-30
An algorithm of the accompanying coordinate expansion and recurrence relation (ACE-RR), which is used for the rapid evaluation of the electron repulsion integral (ERI), has been extended to the general-contraction (GC) scheme. The present algorithm, denoted by GC-ACE-RR, is designed for molecular calculations including heavy elements, whose orbitals consist of many primitive functions with and without higher angular momentum such as d- and f-orbitals. The performance of GC-ACE-RR was assessed for (ss|ss)-, (pp|pp)-, (dd|dd)-, and (ff|ff)-type ERIs in terms of contraction length and the number of GC orbitals. The present algorithm was found to reduce the central processing unit time compared with the ACE-RR algorithm, especially for higher angular momentum and highly contracted orbitals. Compared with HONDOPLUS and GAMESS program packages, GC-ACE-RR computations for ERIs of three-dimensional gold clusters Aun (n = 1, 2, …, 10, 15, 20, and 25) are more than 10 times faster. PMID:24889356
27ps DFT Molecular Dynamics Simulation of a-maltose: A Reduced Basis Set Study.
Technology Transfer Automated Retrieval System (TEKTRAN)
DFT molecular dynamics simulations are time intensive when carried out on carbohydrates such as alpha-maltose, requiring up to three or more weeks on a fast 16-processor computer to obtain just 5ps of constant energy dynamics. In a recent publication [1] forces for dynamics were generated from B3LY...
Zarycz, Natalia; Provasi, Patricio F; Pagola, Gabriel I; Ferraro, Marta B; Pelloni, Stefano; Lazzeretti, Paolo
2016-06-30
In the presence of a static, nonhomogeneous magnetic field, represented by the axial vector B at the origin of the coordinate system and by the polar vector C=∇×B, assumed to be spatially uniform, the chiral molecules investigated in this paper carry an orbital electronic anapole, described by the polar vector A. The electronic interaction energy of these molecules in nonordered media is a cross term, coupling B and C via a¯, one third of the trace of the anapole magnetizability aαβ tensor, that is, WBC=-a¯B·C. Both A and W(BC) have opposite sign in the two enantiomeric forms, a fact quite remarkable from the conceptual point of view. The magnitude of a¯ predicted in the present computational investigation for five chiral molecules is very small and significantly biased by electron correlation contributions, estimated at the density functional level via three different functionals. © 2016 Wiley Periodicals, Inc.
Ab initio modeling of carbohydrates: on the proper selection of computational methods and basis sets
Technology Transfer Automated Retrieval System (TEKTRAN)
With the development of faster computer hardware and quantum mechanical software it has become more feasible to study large carbohydrate molecules via quantum mechanical methods. In the past, studies of carbohydrates were restricted to empirical/semiempirical methods and Hartree Fock. In the last ...
How to select basis sets and computational methods for carbohydrate modeling
Technology Transfer Automated Retrieval System (TEKTRAN)
In the last decade there have been significant improvements in computer hardware but also in development of quantum mechanical methods. This makes it more feasible to study large carbohydrate molecules via quantum mechanical methods whereas in the past studies of carbohydrates were restricted to em...
27ps DFTMD Simulations of Maltose using a Reduced Basis Set
Technology Transfer Automated Retrieval System (TEKTRAN)
The disaccharide, a-maltose, has been studied using constant energy density functional molecular dynamics (DFTMD) at the B3LYP/6-31+G*/4-31G+COSMO (solvent) level of theory. Maltose is of particular interest as the variation in glycosidic dihedral angles has been found to be dependent upon the star...
10 CFR 830.202 - Safety basis.
Code of Federal Regulations, 2010 CFR
2010-01-01
... 10 Energy 4 2010-01-01 2010-01-01 false Safety basis. 830.202 Section 830.202 Energy DEPARTMENT OF ENERGY NUCLEAR SAFETY MANAGEMENT Safety Basis Requirements § 830.202 Safety basis. (a) The contractor responsible for a hazard category 1, 2, or 3 DOE nuclear facility must establish and maintain the safety...
10 CFR 830.202 - Safety basis.
Code of Federal Regulations, 2011 CFR
2011-01-01
... 10 Energy 4 2011-01-01 2011-01-01 false Safety basis. 830.202 Section 830.202 Energy DEPARTMENT OF ENERGY NUCLEAR SAFETY MANAGEMENT Safety Basis Requirements § 830.202 Safety basis. (a) The contractor responsible for a hazard category 1, 2, or 3 DOE nuclear facility must establish and maintain the safety...
10 CFR 830.202 - Safety basis.
Code of Federal Regulations, 2013 CFR
2013-01-01
... 10 Energy 4 2013-01-01 2013-01-01 false Safety basis. 830.202 Section 830.202 Energy DEPARTMENT OF ENERGY NUCLEAR SAFETY MANAGEMENT Safety Basis Requirements § 830.202 Safety basis. (a) The contractor responsible for a hazard category 1, 2, or 3 DOE nuclear facility must establish and maintain the safety...
10 CFR 830.202 - Safety basis.
Code of Federal Regulations, 2014 CFR
2014-01-01
... 10 Energy 4 2014-01-01 2014-01-01 false Safety basis. 830.202 Section 830.202 Energy DEPARTMENT OF ENERGY NUCLEAR SAFETY MANAGEMENT Safety Basis Requirements § 830.202 Safety basis. (a) The contractor responsible for a hazard category 1, 2, or 3 DOE nuclear facility must establish and maintain the safety...
10 CFR 830.202 - Safety basis.
Code of Federal Regulations, 2012 CFR
2012-01-01
... 10 Energy 4 2012-01-01 2012-01-01 false Safety basis. 830.202 Section 830.202 Energy DEPARTMENT OF ENERGY NUCLEAR SAFETY MANAGEMENT Safety Basis Requirements § 830.202 Safety basis. (a) The contractor responsible for a hazard category 1, 2, or 3 DOE nuclear facility must establish and maintain the safety...
Electromagnetic Basis of Metabolism and Heredity
NASA Technical Reports Server (NTRS)
Freund, Friedemann; Stolc, Viktor
2016-01-01
Living organisms control their cellular biological clocks to maintain functional oscillation of the redox cycle, also called the "metabolic cycle" or "respiratory cycle". Organization of cellular processes requires parallel processing on a synchronized time-base. These clocks coordinate the timing of all biochemical processes in the cell, including energy production, DNA replication, and RNA transcription. When this universal time keeping function is perturbed by exogenous induction of reactive oxygen species (ROS), the rate of metabolism changes. This causes oxidative stress, aging and mutations. Therefore, good temporal coordination of the redox cycle not only actively prevents chemical conflict between the reductive and oxidative partial reactions; it also maintains genome integrity and lifespan. Moreover, this universal biochemical rhythm can be disrupted by ROS induction in vivo. This in turn can be achieved by blocking the electron transport chain either endogenously or exogenously by various metabolites, e.g. hydrogen sulfide (H2S), highly diffusible drugs, and carbon monoxide (CO). Alternatively, the electron transport in vivo can be attenuated via a coherent or interfering transfer of energy from exogenous ultralow frequency (ULF) and extremely low frequency (ELF) electromagnetic (EM) fields, suggesting that-on Earth-such ambient fields are an omnipresent (and probably crucially important) factor for the time-setting basis of universal biochemical reactions in living cells. Our work demonstrated previously un-described evidence for quantum effects in biology by electromagnetic coupling below thermal noise at the universal electron transport chain (ETC) in vivo.
Developmental basis of limb homology in lizards.
Fabrezi, Marissa; Abdala, Virginia; Oliver, María Inés Martínez
2007-07-01
Shubin and Alberch (Evol Biol 1986;20:319-387) proposed a scheme of tetrapod limb development based on cartilage morphogenesis that provides the arguments to interpret the homologies of skeletal elements and sets the basis to explain limb specialization through later developmental modification. Morphogenetic evidence emerged from the study of some reptiles, but the availability of data for lizards is limited. Here, the study of adult skeletal variation in 41 lizard taxa and ontogeny in species of Liolaemus and Tupinambis attempts to fill in this gap and provides supporting evidence for the Shubin-Alberch scheme. Six questions are explored. Is there an intermedium in the carpus? Are there two centralia in the carpus? Is there homology among proximal tarsalia of reptiles? Does digit V belong to the digital arch? Is the pisiform an element of the autopodium plan? And should the ossification processes be similar to cartilage morphogenesis? We found the following answers. Some taxa exhibit an ossified element that could represent an intermedium. There is one centrale in the carpus. Development of proximal tarsalia seems to be equivalent with that observed among reptiles. Digit V could arise from the digital arch. Pisiform does not arise as part of the limb plan. And different patterns of ossification occur following a single and conservative cartilaginous configuration. Lizard limb development shows an early pattern common to other reptiles with clear primary axis and digital arch. The pattern then becomes lizard-specific with specialization involving some reduction in prechondrogenic elements. PMID:17415759
NASA Astrophysics Data System (ADS)
Wilby, W. A.; Brett, A. R. H.
Frequency set on techniques used in ECM applications include repeater jammers, frequency memory loops (RF and optical), coherent digital RF memories, and closed loop VCO set on systems. Closed loop frequency set on systems using analog phase and frequency locking are considered to have a number of cost and performance advantages. Their performance is discussed in terms of frequency accuracy, bandwidth, locking time, stability, and simultaneous signals. Some experimental results are presented which show typical locking performance. Future ECM systems might require a response to very short pulses. Acoustooptic and fiber-optic pulse stretching techniques can be used to meet such requirements.
Setting standards: Legislative proposals
Pontius, F.W.
1995-11-01
This article, second of a two-part series examining the standard-setting process reviews legislative proposals that would change the way drinking water standards are set. How drinking water standards should be set and which contaminants should be regulated is a central issue for Safe Drinking Water Act (SDWA) reauthorization. Suggested amendments to the standard-setting provisions of the SDWA cover a broad spectrum of issues. In general, environmental groups argue that standards are not strict enough and that greater consideration should be given to sensitive subpopulations. Others note that the high costs associated with meeting increasingly strict standards are not justified in light of the uncertain and sometimes nonexistent incremental benefits.
Settings for Suicide Prevention
... Sexual Minority" Youth Finds Them at Risk of Violence September 02, 2016 The Weekly Spark Stay Connected! Subscribe Settings Schools, workplaces, hospitals, nursing homes—every place where people ...
Microdosimetric basis for exposure limits.
Brackenbush, L W; Braby, L A
1988-08-01
Consideration of the energy deposited by ionizing radiation in microscopic volumes has led to new insights into dosimetric concepts at the levels of interest in radiation protection. Large amounts of energy are deposited by the passage of low linear-energy-transfer (LET)-charged particles through small volumes. If a typical cell nucleus is considered to be about 7 micron, at an exposure rate of 2.5 X 10(-1) C kg-1 h-1 (1 mR hr-1) from a 60Co irradiation, the average cell nucleus receives one energy deposition event every 12.5 d. Biological processes, which modify radiation damage, typically occur in a few minutes to a few hours. Thus, at occupational exposure levels it is probably the irreparable or misrepaired effects of irradiation that determine the biological consequences. One goal of dosimetry is to measure the incident radiation, making it possible to predict biological risk and set meaningful exposure limits. These measurements must relate to the energy depositions that are responsible for radiation effects at low dose rates, yet the dosimetry system must not be excessively complex to allow use by operational health physicists. Furthermore, our description of the irradiation should be directly measurable. The use of quality factors based upon the energy deposition in a 1-micron-diameter volume of tissue as prescribed in International Commission on Radiation Units Report No. 40 (Joint Task Group 1986) satisfies these requirements. Instrumentation based upon measurement of lineal energy has already been successfully used in health-physics applications. Future changes in the quality factor can be accommodated by changing the algorithm in these microprocessor-based instruments. PMID:3410692
Microdosimetric basis for exposure limits.
Brackenbush, L W; Braby, L A
1988-08-01
Consideration of the energy deposited by ionizing radiation in microscopic volumes has led to new insights into dosimetric concepts at the levels of interest in radiation protection. Large amounts of energy are deposited by the passage of low linear-energy-transfer (LET)-charged particles through small volumes. If a typical cell nucleus is considered to be about 7 micron, at an exposure rate of 2.5 X 10(-1) C kg-1 h-1 (1 mR hr-1) from a 60Co irradiation, the average cell nucleus receives one energy deposition event every 12.5 d. Biological processes, which modify radiation damage, typically occur in a few minutes to a few hours. Thus, at occupational exposure levels it is probably the irreparable or misrepaired effects of irradiation that determine the biological consequences. One goal of dosimetry is to measure the incident radiation, making it possible to predict biological risk and set meaningful exposure limits. These measurements must relate to the energy depositions that are responsible for radiation effects at low dose rates, yet the dosimetry system must not be excessively complex to allow use by operational health physicists. Furthermore, our description of the irradiation should be directly measurable. The use of quality factors based upon the energy deposition in a 1-micron-diameter volume of tissue as prescribed in International Commission on Radiation Units Report No. 40 (Joint Task Group 1986) satisfies these requirements. Instrumentation based upon measurement of lineal energy has already been successfully used in health-physics applications. Future changes in the quality factor can be accommodated by changing the algorithm in these microprocessor-based instruments.
ERIC Educational Resources Information Center
Pellegrino, Linda
2009-01-01
Art history can be a little dry at times, but the author is always trying to incorporate new ways of teaching it. In this article, she describes a project in which students were to create a place setting out of clay that had to be unified through a famous artist's style. This place setting had to consist of at least five pieces (dinner plate, cup…
The topological basis expression of Heisenberg spin chain
NASA Astrophysics Data System (ADS)
Hu, Taotao; Ren, Hang; Xue, Kang
2013-11-01
In this paper, it is shown that the Heisenberg XY, XXZ, XXX, and Ising model all can be constructed from the Braid group algebra generator and the Temperley-Lieb algebra generator. And a new set of topological basis expression is presented. Through acting on the different subspaces, we get the new nontrivial six-dimensional and four-dimensional Braid group matrix representations and Temperley-Lieb matrix representations. The eigenstates of Heisenberg model can be described by the combination of the set of topological bases. It is worth mentioning that the ground state is closely related to parameter q which is the meaningful topological parameter.
NASA Astrophysics Data System (ADS)
Svozil, K.
1995-11-01
Inasmuch as physical theories are formalizable, set theory provides a framework for theoretical physics. Four speculations about the relevance of set theoretical modeling for physics are presented: the role of transcendental set theory (i) in chaos theory, (ii) for paradoxical decompositions of solid three-dimensional objects, (iii) in the theory of effective computability (Church-Turing thesis) related to the possible “solution of supertasks,” and (iv) for weak solutions. Several approaches to set theory and their advantages and disadvatages for physical applications are discussed: Canlorian “naive” (i.e., nonaxiomatic) set theory, contructivism, and operationalism. In the author's opinion, an attitude of “suspended attention” (a term borrowed from psychoanalysis) seems most promising for progress. Physical and set theoretical entities must be operationalized wherever possible. At the same time, physicists should be open to “bizarre” or “mindboggling” new formalisms, which need not be operationalizable or testable at the lime of their creation, but which may successfully lead to novel fields of phenomenology and technology.
Svozil, K.
1995-11-01
Inasmuch as physical theories are formalizable, set theory provides a framework for theoretical physics. Four speculations about the relevance of set theoretical modeling for physics are presented: the role of transcendental set theory (i) in chaos theory, (ii) for paradoxical decompositions of solid three-dimensional objects, (iii) in the theory of effective computability (Church-Turing thesis) related to the possible {open_quotes}solution of supertasks,{close_quotes} and (iv) for weak solutions. Several approaches to set theory and their advantages and disadvantages for physical applications are discussed: Cantorian {open_quotes}naive{close_quotes} (i.e., nonaxiomatic) set theory, contructivism, and operationalism. In the author`s opinion, an attitude, of {open_quotes}suspended attention{close_quotes} (a term borrowed from psychoanalysis) seems most promising for progress. Physical and set theoretical entities must be operationalized wherever possible. At the same time, physicists should be open to {open_quotes}bizarre{close_quotes} or {open_quotes}mindboggling{close_quotes} new formalisms, which need not be operationalizable or testable at the time of their creation, but which may successfully lead to novel fields of phenomenology and technology.
Setting conservation priorities.
Wilson, Kerrie A; Carwardine, Josie; Possingham, Hugh P
2009-04-01
A generic framework for setting conservation priorities based on the principles of classic decision theory is provided. This framework encapsulates the key elements of any problem, including the objective, the constraints, and knowledge of the system. Within the context of this framework the broad array of approaches for setting conservation priorities are reviewed. While some approaches prioritize assets or locations for conservation investment, it is concluded here that prioritization is incomplete without consideration of the conservation actions required to conserve the assets at particular locations. The challenges associated with prioritizing investments through time in the face of threats (and also spatially and temporally heterogeneous costs) can be aided by proper problem definition. Using the authors' general framework for setting conservation priorities, multiple criteria can be rationally integrated and where, how, and when to invest conservation resources can be scheduled. Trade-offs are unavoidable in priority setting when there are multiple considerations, and budgets are almost always finite. The authors discuss how trade-offs, risks, uncertainty, feedbacks, and learning can be explicitly evaluated within their generic framework for setting conservation priorities. Finally, they suggest ways that current priority-setting approaches may be improved.
Is there an optimal basis to maximise optical information transfer?
Chen, Mingzhou; Dholakia, Kishan; Mazilu, Michael
2016-01-01
We establish the concept of the density of the optical degrees of freedom that may be applied to any photonics based system. As a key example of this versatile approach we explore information transfer using optical communication. We demonstrate both experimentally, theoretically and numerically that the use of a basis set with fields containing optical vortices does not increase the telecommunication capacity of an optical system. PMID:26976626
Combining regression trees and radial basis function networks.
Orr, M; Hallam, J; Takezawa, K; Murra, A; Ninomiya, S; Oide, M; Leonard, T
2000-12-01
We describe a method for non-parametric regression which combines regression trees with radial basis function networks. The method is similar to that of Kubat, who was first to suggest such a combination, but has some significant improvements. We demonstrate the features of the new method, compare its performance with other methods on DELVE data sets and apply it to a real world problem involving the classification of soybean plants from digital images.
Set Equation Transformation System.
2002-03-22
Version 00 SETS is used for symbolic manipulation of Boolean equations, particularly the reduction of equations by the application of Boolean identities. It is a flexible and efficient tool for performing probabilistic risk analysis (PRA), vital area analysis, and common cause analysis. The equation manipulation capabilities of SETS can also be used to analyze noncoherent fault trees and determine prime implicants of Boolean functions, to verify circuit design implementation, to determine minimum cost fire protectionmore » requirements for nuclear reactor plants, to obtain solutions to combinatorial optimization problems with Boolean constraints, and to determine the susceptibility of a facility to unauthorized access through nullification of sensors in its protection system. Two auxiliary programs, SEP and FTD, are included. SEP performs the quantitative analysis of reduced Boolean equations (minimal cut sets) produced by SETS. The user can manipulate and evaluate the equations to find the probability of occurrence of any desired event and to produce an importance ranking of the terms and events in an equation. FTD is a fault tree drawing program which uses the proprietary ISSCO DISSPLA graphics software to produce an annotated drawing of a fault tree processed by SETS. The DISSPLA routines are not included.« less
NASA Astrophysics Data System (ADS)
Ellerman, David
2014-03-01
In models of QM over finite fields (e.g., Schumacher's ``modal quantum theory'' MQT), one finite field stands out, Z2, since Z2 vectors represent sets. QM (finite-dimensional) mathematics can be transported to sets resulting in quantum mechanics over sets or QM/sets. This gives a full probability calculus (unlike MQT with only zero-one modalities) that leads to a fulsome theory of QM/sets including ``logical'' models of the double-slit experiment, Bell's Theorem, QIT, and QC. In QC over Z2 (where gates are non-singular matrices as in MQT), a simple quantum algorithm (one gate plus one function evaluation) solves the Parity SAT problem (finding the parity of the sum of all values of an n-ary Boolean function). Classically, the Parity SAT problem requires 2n function evaluations in contrast to the one function evaluation required in the quantum algorithm. This is quantum speedup but with all the calculations over Z2 just like classical computing. This shows definitively that the source of quantum speedup is not in the greater power of computing over the complex numbers, and confirms the idea that the source is in superposition.
Conceptual frameworks for setting environmental standards.
Philipp, R
1996-01-01
Following the Second European Conference on Environment and Health, held from 20 to 22 June 1994 in Helsinki, the World Health Organization (WHO) established a National Environmental Health Action Plan pilot project. During 1995, and as part of its work for this project with the WHO European Environmental Health Committee, the UK Royal Commission on Environmental Pollution began to seek evidence for the basis of setting environmental standards and to ask if a more consistent and robust basis can be found for establishing them. This paper explores the conceptual frameworks needed to help establish policy and address practical questions associated with different pollutants, exposures and environmental settings. It addresses sustainable development, inter-generational equity and environmental quality, the European Charter on Environment and Health, the Treaty of Maastricht, economic, educational and training issues, risk assessment, the role of environmental epidemiology, and definitions of environmental quality objectives, environmental health indicators, environmental epidemiology and environmental impact assessment.
42 CFR 416.75 - Performance of listed surgical procedures on an inpatient hospital basis.
Code of Federal Regulations, 2010 CFR
2010-10-01
... inpatient hospital basis. 416.75 Section 416.75 Public Health CENTERS FOR MEDICARE & MEDICAID SERVICES... on an inpatient hospital basis. The inclusion of any procedure as a covered surgical procedure under § 416.65 does not preclude its coverage in an inpatient hospital setting under Medicare....
ERIC Educational Resources Information Center
Greenslade, Thomas B., Jr.
2014-01-01
In past issues of this journal, the late H. R. Crane wrote a long series of articles under the running title of "How Things Work." In them, Dick dealt with many questions that physics teachers asked themselves, but did not have the time to answer. This article is my attempt to work through the physics of the crystal set, which I thought…
ERIC Educational Resources Information Center
Sparks, Dennis C.
1978-01-01
Action goal setting uses power of peer influence in a healthy and constructive manner, and provides appropriate follow-up for many counseling and classroom activities. This process could help individuals of all ages to take more control over their behavior and create life-styles congruent with their abilities, interests, and values. (Author)
Setting Environmental Standards
ERIC Educational Resources Information Center
Fishbein, Gershon
1975-01-01
Recent court decisions have pointed out the complexities involved in setting environmental standards. Environmental health is composed of multiple causative agents, most of which work over long periods of time. This makes the cause-and-effect relationship between health statistics and environmental contaminant exposures difficult to prove in…
TRACKING ACCELERATOR SETTINGS.
D OTTAVIO,T.; FU, W.; OTTAVIO, D.P.
2007-10-15
Recording setting changes within an accelerator facility provides information that can be used to answer questions about when, why, and how changes were made to some accelerator system. This can be very useful during normal operations, but can also aid with security concerns and in detecting unusual software behavior. The Set History System (SHS) is a new client-server system developed at the Collider-Accelerator Department of Brookhaven National Laboratory to provide these capabilities. The SHS has been operational for over two years and currently stores about IOOK settings per day into a commercial database management system. The SHS system consists of a server written in Java, client tools written in both Java and C++, and a web interface for querying the database of setting changes. The design of the SHS focuses on performance, portability, and a minimal impact on database resources. In this paper, we present an overview of the system design along with benchmark results showing the performance and reliability of the SHS over the last year.
Therapists in Oncology Settings
ERIC Educational Resources Information Center
Hendrick, Susan S.
2013-01-01
This article describes the author's experiences of working with cancer patients/survivors both individually and in support groups for many years, across several settings. It also documents current best-practice guidelines for the psychosocial treatment of cancer patients/survivors and their families. The author's view of the important qualities…
Authorization basis for the 209-E Building
TIFFANY, M.S.
1999-02-23
This Authorization Basis document is one of three documents that constitute the Authorization Basis for the 209-E Building. Per the U.S. Department of Energy, Richland Operations Office (RL) letter 98-WSD-074, this document, the 209-E Building Preliminary Hazards Analysis (WHC-SD-WM-TI-789), and the 209-E Building Safety Evaluation Report (97-WSD-074) constitute the Authorization Basis for the 209-E Building. This Authorization Basis and the associated controls and safety programs will remain in place until safety documentation addressing deactivation of the 209-E Building is developed by the contractor and approved by RL.
Introduction of a Novel Dimension in Young Children's Learning Sets.
ERIC Educational Resources Information Center
Williams, Deborah Anne; Cameron, Catherine Ann
The effect of stimulus novelty, an attentional variable, on learning set acquisition was investigated. Learning set (LS) acquisition refers to an improvement in performance across a series of problems which have a common basis of solution. The design of this study involved two groups, one in which the positive stimulus on Trial 2 involved the…
Keyworth urges setting priorities
NASA Astrophysics Data System (ADS)
A strong advocate of scientists setting priorities within their disciplines, George A. Keyworth, II, President Reagan's science advisor and director of the Office of Science and Technology Policy, recently offered three possible consequences if such priorities are not set.‘I'm especially worried about the continued inability—or unwillingness—of the science community to agree among themselves about priorities—or to abide by their decisions when they can agree,’ he said [emphasis his]. ‘I wouldn't think it necessary that I remind them that these are tough times. I'll add that for anyone depending on federal funding, they're going to remain tough, times for quite a while,’ Keyworth told the American Physical Society at its mid-April meeting in Baltimore, Md.
Setting mastery learning standards.
Yudkowsky, Rachel; Park, Yoon Soo; Lineberry, Matthew; Knox, Aaron; Ritter, E Matthew
2015-11-01
Mastery learning is an instructional approach in which educational progress is based on demonstrated performance, not curricular time. Learners practice and retest repeatedly until they reach a designated mastery level; the final level of achievement is the same for all, although time to mastery may vary. Given the unique properties of mastery learning assessments, a thoughtful approach to establishing the performance levels and metrics that determine when a learner has demonstrated mastery is essential.Standard-setting procedures require modification when used for mastery learning settings in health care, particularly regarding the use of evidence-based performance data, the determination of appropriate benchmark or comparison groups, and consideration of patient safety consequences. Information about learner outcomes and past performance data of learners successful at the subsequent level of training can be more helpful than traditional information about test performance of past examinees. The marginally competent "borderline student" or "borderline group" referenced in traditional item-based and examinee-based procedures will generally need to be redefined in mastery settings. Patient safety considerations support conjunctive standards for key knowledge and skill subdomains and for items that have an impact on clinical outcomes. Finally, traditional psychometric indices used to evaluate the quality of standards do not necessarily reflect critical measurement properties of mastery assessments. Mastery learning and testing are essential to the achievement and assessment of entrustable professional activities and residency milestones. With careful attention, sound mastery standard-setting procedures can provide an essential step toward improving the effectiveness of health professions education, patient safety, and patient care. PMID:26375263
NASA Astrophysics Data System (ADS)
Greenslade, Thomas B.
2014-04-01
In past issues of this journal, the late H. R. Crane wrote a long series of articles under the running title of "How Things Work." In them, Dick dealt with many questions that physics teachers asked themselves, but did not have the time to answer. This article is my attempt to work through the physics of the crystal set, which I thought I knew, but actually did not.
Code of Federal Regulations, 2014 CFR
2014-10-01
... 47 Telecommunication 1 2014-10-01 2014-10-01 false Basis. 10.1 Section 10.1 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL WIRELESS EMERGENCY ALERTS General Information § 10.1 Basis. The rules in this part are issued pursuant to the authority contained in the Warning, Alert, and...
Code of Federal Regulations, 2013 CFR
2013-10-01
... 47 Telecommunication 1 2013-10-01 2013-10-01 false Basis. 10.1 Section 10.1 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL WIRELESS EMERGENCY ALERTS General Information § 10.1 Basis. The rules in this part are issued pursuant to the authority contained in the Warning, Alert, and...
Code of Federal Regulations, 2010 CFR
2010-07-01
... 29 Labor 3 2010-07-01 2010-07-01 false Casual basis. 552.5 Section 552.5 Labor Regulations Relating to Labor (Continued) WAGE AND HOUR DIVISION, DEPARTMENT OF LABOR REGULATIONS APPLICATION OF THE FAIR LABOR STANDARDS ACT TO DOMESTIC SERVICE General Regulations § 552.5 Casual basis. As used...
Code of Federal Regulations, 2011 CFR
2011-07-01
... 29 Labor 3 2011-07-01 2011-07-01 false Casual basis. 552.5 Section 552.5 Labor Regulations Relating to Labor (Continued) WAGE AND HOUR DIVISION, DEPARTMENT OF LABOR REGULATIONS APPLICATION OF THE FAIR LABOR STANDARDS ACT TO DOMESTIC SERVICE General Regulations § 552.5 Casual basis. As used...
Code of Federal Regulations, 2012 CFR
2012-07-01
... 29 Labor 3 2012-07-01 2012-07-01 false Casual basis. 552.5 Section 552.5 Labor Regulations Relating to Labor (Continued) WAGE AND HOUR DIVISION, DEPARTMENT OF LABOR REGULATIONS APPLICATION OF THE FAIR LABOR STANDARDS ACT TO DOMESTIC SERVICE General Regulations § 552.5 Casual basis. As used...
Code of Federal Regulations, 2013 CFR
2013-07-01
... 29 Labor 3 2013-07-01 2013-07-01 false Casual basis. 552.5 Section 552.5 Labor Regulations Relating to Labor (Continued) WAGE AND HOUR DIVISION, DEPARTMENT OF LABOR REGULATIONS APPLICATION OF THE FAIR LABOR STANDARDS ACT TO DOMESTIC SERVICE General Regulations § 552.5 Casual basis. As used...
Code of Federal Regulations, 2014 CFR
2014-07-01
... 29 Labor 3 2014-07-01 2014-07-01 false Casual basis. 552.5 Section 552.5 Labor Regulations Relating to Labor (Continued) WAGE AND HOUR DIVISION, DEPARTMENT OF LABOR REGULATIONS APPLICATION OF THE FAIR LABOR STANDARDS ACT TO DOMESTIC SERVICE General Regulations § 552.5 Casual basis. As used...
42 CFR 406.1 - Statutory basis.
Code of Federal Regulations, 2010 CFR
2010-10-01
... 42 Public Health 2 2010-10-01 2010-10-01 false Statutory basis. 406.1 Section 406.1 Public Health CENTERS FOR MEDICARE & MEDICAID SERVICES, DEPARTMENT OF HEALTH AND HUMAN SERVICES MEDICARE PROGRAM HOSPITAL INSURANCE ELIGIBILITY AND ENTITLEMENT General Provisions § 406.1 Statutory basis. Sections...
Code of Federal Regulations, 2013 CFR
2013-04-01
... 21 Food and Drugs 2 2013-04-01 2013-04-01 false Legal basis. 120.9 Section 120.9 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION HAZARD ANALYSIS AND CRITICAL CONTROL POINT (HACCP) SYSTEMS General Provisions § 120.9 Legal basis. Failure of a processor to have and...
42 CFR 408.200 - Statutory basis.
Code of Federal Regulations, 2010 CFR
2010-10-01
... 42 Public Health 2 2010-10-01 2010-10-01 false Statutory basis. 408.200 Section 408.200 Public Health CENTERS FOR MEDICARE & MEDICAID SERVICES, DEPARTMENT OF HEALTH AND HUMAN SERVICES MEDICARE PROGRAM... § 408.200 Statutory basis. This subpart implements provisions of section 1839(e) of the Social...
Code of Federal Regulations, 2010 CFR
2010-10-01
... 42 Public Health 4 2010-10-01 2010-10-01 false Basis. 460.2 Section 460.2 Public Health CENTERS FOR MEDICARE & MEDICAID SERVICES, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) Basis,...
Code of Federal Regulations, 2011 CFR
2011-10-01
... 42 Public Health 4 2011-10-01 2011-10-01 false Basis. 460.2 Section 460.2 Public Health CENTERS FOR MEDICARE & MEDICAID SERVICES, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) Basis,...
Code of Federal Regulations, 2012 CFR
2012-10-01
... 42 Public Health 4 2012-10-01 2012-10-01 false Basis. 460.2 Section 460.2 Public Health CENTERS FOR MEDICARE & MEDICAID SERVICES, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) Basis,...
Code of Federal Regulations, 2013 CFR
2013-10-01
... 42 Public Health 4 2013-10-01 2013-10-01 false Basis. 460.2 Section 460.2 Public Health CENTERS FOR MEDICARE & MEDICAID SERVICES, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) Basis,...
Code of Federal Regulations, 2014 CFR
2014-10-01
... 42 Public Health 4 2014-10-01 2014-10-01 false Basis. 460.2 Section 460.2 Public Health CENTERS FOR MEDICARE & MEDICAID SERVICES, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) PROGRAMS OF ALL-INCLUSIVE CARE FOR THE ELDERLY (PACE) Basis,...
Code of Federal Regulations, 2010 CFR
2010-04-01
... 20 Employees' Benefits 3 2010-04-01 2010-04-01 false Basis. 900.1 Section 900.1 Employees' Benefits JOINT BOARD FOR THE ENROLLMENT OF ACTUARIES STATEMENT OF ORGANIZATION § 900.1 Basis. This statement is issued by the Joint Board for the Enrollment of Actuaries (the Joint Board) pursuant to...
42 CFR 418.1 - Statutory basis.
Code of Federal Regulations, 2010 CFR
2010-10-01
... 42 Public Health 3 2010-10-01 2010-10-01 false Statutory basis. 418.1 Section 418.1 Public Health CENTERS FOR MEDICARE & MEDICAID SERVICES, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICARE PROGRAM HOSPICE CARE General Provision and Definitions § 418.1 Statutory basis. This part...
42 CFR 418.1 - Statutory basis.
Code of Federal Regulations, 2013 CFR
2013-10-01
... 42 Public Health 3 2013-10-01 2013-10-01 false Statutory basis. 418.1 Section 418.1 Public Health CENTERS FOR MEDICARE & MEDICAID SERVICES, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICARE PROGRAM (CONTINUED) HOSPICE CARE General Provision and Definitions § 418.1 Statutory basis. This...
42 CFR 418.1 - Statutory basis.
Code of Federal Regulations, 2012 CFR
2012-10-01
... 42 Public Health 3 2012-10-01 2012-10-01 false Statutory basis. 418.1 Section 418.1 Public Health CENTERS FOR MEDICARE & MEDICAID SERVICES, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICARE PROGRAM (CONTINUED) HOSPICE CARE General Provision and Definitions § 418.1 Statutory basis. This...
42 CFR 418.1 - Statutory basis.
Code of Federal Regulations, 2014 CFR
2014-10-01
... 42 Public Health 3 2014-10-01 2014-10-01 false Statutory basis. 418.1 Section 418.1 Public Health CENTERS FOR MEDICARE & MEDICAID SERVICES, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICARE PROGRAM (CONTINUED) HOSPICE CARE General Provision and Definitions § 418.1 Statutory basis. This...
42 CFR 418.1 - Statutory basis.
Code of Federal Regulations, 2011 CFR
2011-10-01
... 42 Public Health 3 2011-10-01 2011-10-01 false Statutory basis. 418.1 Section 418.1 Public Health CENTERS FOR MEDICARE & MEDICAID SERVICES, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICARE PROGRAM HOSPICE CARE General Provision and Definitions § 418.1 Statutory basis. This part...
Tilford, Charles A; Siemers, Nathan O
2009-01-01
Set enrichment analytical methods have become commonplace tools applied to the analysis and interpretation of biological data. The statistical techniques are used to identify categorical biases within lists of genes, proteins, or metabolites. The goal is to discover the shared functions or properties of the biological items represented within the lists. Application of these methods can provide great biological insight, including the discovery of participation in the same biological activity or pathway, shared interacting genes or regulators, common cellular compartmentalization, or association with disease. The methods require ordered or unordered lists of biological items as input, understanding of the reference set from which the lists were selected, categorical classifiers describing the items, and a statistical algorithm to assess bias of each classifier. Due to the complexity of most algorithms and the number of calculations performed, computer software is almost always used for execution of the algorithm, as well as for presentation of the results. This chapter will provide an overview of the statistical methods used to perform an enrichment analysis. Guidelines for assembly of the requisite information will be presented, with a focus on careful definition of the sets used by the statistical algorithms. The need for multiple test correction when working with large libraries of classifiers is emphasized, and we outline several options for performing the corrections. Finally, interpreting the results of such analysis will be discussed along with examples of recent research utilizing the techniques.
Setting Goals for Achievement in Physical Education Settings
ERIC Educational Resources Information Center
Baghurst, Timothy; Tapps, Tyler; Kensinger, Weston
2015-01-01
Goal setting has been shown to improve student performance, motivation, and task completion in academic settings. Although goal setting is utilized by many education professionals to help students set realistic and proper goals, physical educators may not be using goal setting effectively. Without incorporating all three types of goals and…
Surface interpolation with radial basis functions for medical imaging
Carr, J.C.; Beatson, R.K.; Fright, W.R.
1997-02-01
Radial basis functions are presented as a practical solution to the problem of interpolating incomplete surfaces derived from three-dimensional (3-D) medical graphics. The specific application considered is the design of cranial implants for the repair of defects, usually holes, in the skull. Radial basis functions impose few restrictions on the geometry of the interpolation centers and are suited to problems where interpolation centers do not form a regular grid. However, their high computational requirements have previously limited their use to problems where the number of interpolation centers is small (<300). Recently developed fast evaluation techniques have overcome these limitations and made radial basis interpolation a practical approach for larger data sets. In this paper radial basis functions are fitted to depth-maps of the skull`s surface, obtained from X-ray computed tomography (CT) data using ray-tracing techniques. They are used to smoothly interpolate the surface of the skull across defect regions. The resulting mathematical description of the skull`s surface can be evaluated at any desired resolution to be rendered on a graphics workstation or to generate instructions for operating a computer numerically controlled (CNC) mill.
Density-functional expansion methods: Generalization of the auxiliary basis
Giese, Timothy J.; York, Darrin M.
2011-01-01
The formulation of density-functional expansion methods is extended to treat the second and higher-order terms involving the response density and spin densities with an arbitrary single-center auxiliary basis. The two-center atomic orbital products are represented by the auxiliary functions centered about those two atoms, and the mapping coefficients are determined from a local constrained variational procedure. This two-center variational procedure allows the mapping coefficients to be pretabulated and splined as a function of internuclear separation for efficient look up. The splines of mapping coefficients have a range no longer than that of the overlap integrals, and the auxiliary density appears as a single point-multipole expansion to all nonoverlapping atoms, thus allowing for the trivial implementation of a linear-scaling algorithm. The method is tested using Gaussian multipole expansions, and the effect of angular and radial completeness is explored. Several auxiliary basis sets are parametrized and compared to an auxiliary basis analogous to that used in the self-consistent-charge density-functional tight-binding model, and the method is demonstrated to greatly improve the representation of the density response with respect to a reference expansion model that does not use an auxiliary basis. PMID:21599040
Solar Power Tower Design Basis Document, Revision 0
ZAVOICO,ALEXIS B.
2001-07-01
This report contains the design basis for a generic molten-salt solar power tower. A solar power tower uses a field of tracking mirrors (heliostats) that redirect sunlight on to a centrally located receiver mounted on top a tower, which absorbs the concentrated sunlight. Molten nitrate salt, pumped from a tank at ground level, absorbs the sunlight, heating it up to 565 C. The heated salt flows back to ground level into another tank where it is stored, then pumped through a steam generator to produce steam and make electricity. This report establishes a set of criteria upon which the next generation of solar power towers will be designed. The report contains detailed criteria for each of the major systems: Collector System, Receiver System, Thermal Storage System, Steam Generator System, Master Control System, and Electric Heat Tracing System. The Electric Power Generation System and Balance of Plant discussions are limited to interface requirements. This design basis builds on the extensive experience gained from the Solar Two project and includes potential design innovations that will improve reliability and lower technical risk. This design basis document is a living document and contains several areas that require trade-studies and design analysis to fully complete the design basis. Project- and site-specific conditions and requirements will also resolve open To Be Determined issues.
Telemedicine in educational settings.
Newton, Heather
The use of telemedicine to enhance patient care is well documented in the literature (Currell et al 2001); however, its use in educational settings requires further exploration. Technological advances in electronic communication have been the catalyst for enabling the transmission and storage of large volumes of data. This, in turn, has allowed still and video images to be used for clinical consultation and the advancement of healthcare professionals' knowledge and skills. This article discusses the use of telemedicine in healthcare practices and explores its value as an educational tool, particularly in the field of wound care.
Keasler, J A
2012-03-27
Vectorization is data parallelism (SIMD, SIMT, etc.) - extension of ISA enabling the same instruction to be performed on multiple data items simultaeously. Many/most CPUs support vectorization in some form. Vectorization is difficult to enable, but can yield large efficiency gains. Extra programmer effort is required because: (1) not all algorithms can be vectorized (regular algorithm structure and fine-grain parallelism must be used); (2) most CPUs have data alignment restrictions for load/store operations (obey or risk incorrect code); (3) special directives are often needed to enable vectorization; and (4) vector instructions are architecture-specific. Vectorization is the best way to optimize for power and performance due to reduced clock cycles. When data is organized properly, a vector load instruction (i.e. movaps) can replace 'normal' load instructions (i.e. movsd). Vector operations can potentially have a smaller footprint in the instruction cache when fewer instructions need to be executed. Hybrid index sets insulate users from architecture specific details. We have applied hybrid index sets to achieve optimal vectorization. We can extend this concept to handle other programming models.
Basis convergence of range-separated density-functional theory
Franck, Odile Mussard, Bastien; Luppi, Eleonora Toulouse, Julien
2015-02-21
Range-separated density-functional theory (DFT) is an alternative approach to Kohn-Sham density-functional theory. The strategy of range-separated density-functional theory consists in separating the Coulomb electron-electron interaction into long-range and short-range components and treating the long-range part by an explicit many-body wave-function method and the short-range part by a density-functional approximation. Among the advantages of using many-body methods for the long-range part of the electron-electron interaction is that they are much less sensitive to the one-electron atomic basis compared to the case of the standard Coulomb interaction. Here, we provide a detailed study of the basis convergence of range-separated density-functional theory. We study the convergence of the partial-wave expansion of the long-range wave function near the electron-electron coalescence. We show that the rate of convergence is exponential with respect to the maximal angular momentum L for the long-range wave function, whereas it is polynomial for the case of the Coulomb interaction. We also study the convergence of the long-range second-order Møller-Plesset correlation energy of four systems (He, Ne, N{sub 2}, and H{sub 2}O) with cardinal number X of the Dunning basis sets cc − p(C)V XZ and find that the error in the correlation energy is best fitted by an exponential in X. This leads us to propose a three-point complete-basis-set extrapolation scheme for range-separated density-functional theory based on an exponential formula.
Code of Federal Regulations, 2010 CFR
2010-10-01
... CENTERS FOR MEDICARE & MEDICAID SERVICES, DEPARTMENT OF HEALTH AND HUMAN SERVICES MEDICARE PROGRAM FEDERAL... Services § 405.2400 Basis. Subpart X is based on the provisions of the following sections of the Act... covered by the Medicare program....
Generalized multiscale radial basis function networks.
Billings, Stephen A; Wei, Hua-Liang; Balikhin, Michael A
2007-12-01
A novel modelling framework is proposed for constructing parsimonious and flexible multiscale radial basis function networks (RBF). Unlike a conventional standard single scale RBF network, where all the basis functions have a common kernel width, the new network structure adopts multiscale Gaussian functions as the bases, where each selected centre has multiple kernel widths, to provide more flexible representations with better generalization properties for general nonlinear dynamical systems. As a direct extension of the traditional single scale Gaussian networks, the new multiscale network is easy to implement and is quick to learn using standard learning algorithms. A k-means clustering algorithm and an improved orthogonal least squares (OLS) algorithm are used to determine the unknown parameters in the network model including the centres and widths of the basis functions, and the weights between the basis functions. It is demonstrated that the new network can lead to a parsimonious model with much better generalization property compared with the traditional single width RBF networks.
Enhancing ℓ1-minimization estimates of polynomial chaos expansions using basis selection
NASA Astrophysics Data System (ADS)
Jakeman, J. D.; Eldred, M. S.; Sargsyan, K.
2015-05-01
In this paper we present a basis selection method that can be used with ℓ1-minimization to adaptively determine the large coefficients of polynomial chaos expansions (PCE). The adaptive construction produces anisotropic basis sets that have more terms in important dimensions and limits the number of unimportant terms that increase mutual coherence and thus degrade the performance of ℓ1-minimization. The important features and the accuracy of basis selection are demonstrated with a number of numerical examples. Specifically, we show that for a given computational budget, basis selection produces a more accurate PCE than would be obtained if the basis were fixed a priori. We also demonstrate that basis selection can be applied with non-uniform random variables and can leverage gradient information.
Brown, Raymond J.
1977-01-01
The present invention relates to a tool setting device for use with numerically controlled machine tools, such as lathes and milling machines. A reference position of the machine tool relative to the workpiece along both the X and Y axes is utilized by the control circuit for driving the tool through its program. This reference position is determined for both axes by displacing a single linear variable displacement transducer (LVDT) with the machine tool through a T-shaped pivotal bar. The use of the T-shaped bar allows the cutting tool to be moved sequentially in the X or Y direction for indicating the actual position of the machine tool relative to the predetermined desired position in the numerical control circuit by using a single LVDT.
Structural Basis for Protein Phosphatase 1 Regulation and Specificity
Peti, Wolfgang; Nairn, Angus C.; Page, Rebecca
2012-01-01
The ubiquitous Ser/Thr Protein Phosphatase 1 (PP1) regulates diverse, essential cellular processes such as cell cycle progression, protein synthesis, muscle contraction, carbohydrate metabolism, transcription and neuronal signaling. However, the free catalytic subunit of PP1, while an effective enzyme, lacks substrate specificity. Instead, it depends on a diverse set of regulatory proteins (≥200) to confer specificity towards distinct substrates. Here, we discuss recent advances in structural studies of PP1 holoenzyme complexes and summarize the new insights these studies have provided into the molecular basis of PP1 regulation and specificity. PMID:22284538
Anderson, H C; Lotfi, A; Westphal, L C; Jang, J R
1998-01-01
The above paper claims that under a set of minor restrictions radial basis function networks and fuzzy inference systems are functionally equivalent. The purpose of this letter is to show that this set of restrictions is incomplete and that, when it is completed, the said functional equivalence applies only to a small range of fuzzy inference systems. In addition, a modified set of restrictions is proposed which is applicable for a much wider range of fuzzy inference systems.
Telemedicine in clinical setting
Zhang, Xiao-Ying; Zhang, Peiying
2016-01-01
The telemedicine department of a hospital is an emerging branch in upcoming hospitals and may become an essential component of every hospital. It basically utilizes the information technologies along with telecommunication systems in order to provide clinical care and assistance. Furthermore, the branch of telemedicine offers significant opportunities for the process of developmental freedom from illness, early death, and preventable diseases. It advances development by providing relevant drugs and the necessary care aimed to alleviate patient suffering. It is also beneficial for patients in rural remote areas who usually do not have adequate access to advanced hospitals. Telemedicine in these remote areas allows for timely treatment of emergency cases. Thus, it contributes towards remote emergency critical care in order to save lives in crucial cases. Additionally, the emerging advances have now enabled telemedicine to transfer large amounts of clinical informatics data including images, and test reports to the specifically specialized health professionals in some serious cases. However, as in the case of many emerging technologies, organizing information and understanding the field has significant challenges. The present review article aimed to discuss important aspects of the field with regard to the better management of patients in clinical settings. PMID:27703503
Fuzzy sets applications for cancer risk assessment.
Molchanov, P A; Dudatiev, A V; Podobna, Y Y; Molchanova, O P
2002-09-01
The method of cancer risk assessment on the basis of the Fuzzy Set Theory is presented. The method is based on a multifactor risk assessment of cancer diseases. The individual risk of cancer disease is evaluated as the probability of disease multiplied by the value of an individual dose. An acupuncture method of cancer risk assessments was developed. The method is based on the analysis of changes of an electromagnetic field (biofield) of a person. The method allows to determine both cancer probability and probable location of the process.
TMD PDFs in the Laguerre polynomial basis
NASA Astrophysics Data System (ADS)
Vladimirov, A. A.
2014-08-01
We suggest the modified matching procedure for TMD PDF to the integrated PDF aimed to increase the amount of perturbative information in the TMD PDF expression. The procedure consists in the selection and usage of the non-minimal operator basis, which restricts the expansion to desired general behavior. The implication of OPE allows to systematic account of the higher order corrections. In the case of TMD PDF we assume the Gaussian behavior, which suggests Laguerre polynomial basis as the best for the convergence of OPE. We present the leading and next-to-leading expression of TMD PDF in this basis. The obtained perturbative expression for the TMD PDF is valid in the wide region of b T (we estimate this region as b T ≲ 2 - 3 GeV-1 depending on x).
Field-Line Resonances in the Current Basis
NASA Astrophysics Data System (ADS)
Ostaszewski, Katharina; Glassmeier, Karl-Heinz; Nabert, Christian
2016-04-01
The MHD theory of the field-line resonance is of great importance for the understanding of ultra low-frequency waves in the magnetosphere. Most theoretical works concerning field-line resonance use the electric field as the basis set. In an ideal MHD plasma the field-aligned component of the electrical field vanishes because of the frozen-in theorem. However, a field-aligned current flows to maintain quasi-neutrality. This field-aligned current can only be carried by the transverse MHD Alfvèn wave and is therefore a characteristic feature of these types of waves. In this study we investigate the field-line resonance phenomenon using a three dimensional current vector space as the basis set. Using the model of the box magnetosphere of Southwood (1974) we derive an equation for the field-aligned current. This equation provides a simpler and more detailed insight into the coupling process between the fast mode and the Alfvèn mode. Furthermore we investigate the effect of the Hall current on the field-aligned current by including the Hall term in Ohm's law. It is shown that in some situations the Hall current can nullify the filed-aligned current and therefore prevent the resonance.
Leadership and priority setting: the perspective of hospital CEOs.
Reeleder, David; Goel, Vivek; Singer, Peter A; Martin, Douglas K
2006-11-01
The role of leadership in health care priority setting remains largely unexplored. While the management leadership literature has grown rapidly, the growing literature on priority setting in health care has looked in other directions to improve priority setting practices--to health economics and ethical approaches. Consequently, potential for improvement in hospital priority setting practices may be overlooked. A qualitative study involving interviews with 46 Ontario hospital CEOs was done to describe the role of leadership in priority setting through the perspective of hospital leaders. For the first time, we report a framework of leadership domains including vision, alignment, relationships, values and process to facilitate priority setting practices in health services' organizations. We believe this fledgling framework forms the basis for the sharing of good leadership practices for health reform. It also provides a leadership guide for decision makers to improve the quality of their leadership, and in so doing, we believe, the fairness of their priority setting. PMID:16377023
Full Waveform Inversion with Optimal Basis Functions
NASA Astrophysics Data System (ADS)
Sun, Gang; Chang, Qianshun; Sheng, Ping
2003-03-01
Based on the approach suggested by Tarantola, and Gauthier etal., we show that the alternate use of the step (linear) function basis and the block function (quasi-δ function) basis can give accurate full waveform inversion results for the layered acoustic systems, starting from a uniform background. Our method is robust against additive white noise (up to 20% of the signal) and can resolve layers that are comparable to or smaller than a wavelength in thickness. The physical reason for the success of our approach is illustrated through a simple example.
Full waveform inversion with optimal basis functions.
Sun, Gang; Chang, Qianshun; Sheng, Ping
2003-03-14
Based on the approach suggested by Tarantola, and Gauthier et al., we show that the alternate use of the step (linear) function basis and the block function (quasi-delta function) basis can give accurate full waveform inversion results for the layered acoustic systems, starting from a uniform background. Our method is robust against additive white noise (up to 20% of the signal) and can resolve layers that are comparable to or smaller than a wavelength in thickness. The physical reason for the success of our approach is illustrated through a simple example.
The Q field, a variable quaternion basis
Efremov, A.P.
1986-06-01
The author introduces the concept of the Q field as a 2 x 2 matrix representation of the variable basis of vectors satisfying the rule of multiplication of quaternion imaginary numbers and as an element of the group of transformations of the basis preserving the invariance of this multiplication rule. The rule for projecting such matrices on a given direction is determined with the help of the characteristic functions of the matrices-vectors of the Q field. The differential structure of Q fields is studied and the theory developed is illustrated by an example of a model-topological classification of particles according to the magnitude of their spin.
A Set of Questions, A Question of Sets.
ERIC Educational Resources Information Center
Mathematics in School, 1985
1985-01-01
Two versions of a page of exercises using set ideas are presented, one in plain language and one in technical language. Some questions and answers about the appropriateness of set terminology and symbols are then given. (MNS)
Explicitly correlated atomic orbital basis second order Møller-Plesset theory.
Hollman, David S; Wilke, Jeremiah J; Schaefer, Henry F
2013-02-14
The scope of problems treatable by ab initio wavefunction methods has expanded greatly through the application of local approximations. In particular, atomic orbital (AO) based wavefunction methods have emerged as powerful techniques for exploiting sparsity and have been applied to biomolecules as large as 1707 atoms [S. A. Maurer, D. S. Lambrecht, D. Flaig, and C. Ochsenfeld, J. Chem. Phys. 136, 144107 (2012)]. Correlated wavefunction methods, however, converge notoriously slowly to the basis set limit and, excepting the use of large basis sets, will suffer from a severe basis set incompleteness error (BSIE). The use of larger basis sets is prohibitively expensive for AO basis methods since, for example, second-order Møller-Plesset perturbation theory (MP2) scales linearly with the number of atoms, but still scales as O(N(5)) in the number of functions per atom. Explicitly correlated F12 methods have been shown to drastically reduce BSIE for even modestly sized basis sets. In this work, we therefore explore an atomic orbital based formulation of explicitly correlated MP2-F12 theory. We present working equations for the new method, which produce results identical to the widely used molecular orbital (MO) version of MP2-F12 without resorting to a delocalized MO basis. We conclude with a discussion of several possible approaches to a priori screening of contraction terms in our method and the prospects for a linear scaling implementation of AO-MP2-F12. The discussion includes concrete examples involving noble gas dimers and linear alkane chains.
23 CFR 140.904 - Reimbursement basis.
Code of Federal Regulations, 2010 CFR
2010-04-01
... 23 Highways 1 2010-04-01 2010-04-01 false Reimbursement basis. 140.904 Section 140.904 Highways FEDERAL HIGHWAY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION PAYMENT PROCEDURES REIMBURSEMENT... program. (2) Incurred subsequent to the date of authorization by the Federal Highway Administration...
23 CFR 140.904 - Reimbursement basis.
Code of Federal Regulations, 2014 CFR
2014-04-01
... 23 Highways 1 2014-04-01 2014-04-01 false Reimbursement basis. 140.904 Section 140.904 Highways FEDERAL HIGHWAY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION PAYMENT PROCEDURES REIMBURSEMENT... program. (2) Incurred subsequent to the date of authorization by the Federal Highway Administration...
23 CFR 140.904 - Reimbursement basis.
Code of Federal Regulations, 2012 CFR
2012-04-01
... 23 Highways 1 2012-04-01 2012-04-01 false Reimbursement basis. 140.904 Section 140.904 Highways FEDERAL HIGHWAY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION PAYMENT PROCEDURES REIMBURSEMENT... program. (2) Incurred subsequent to the date of authorization by the Federal Highway Administration...
23 CFR 140.904 - Reimbursement basis.
Code of Federal Regulations, 2011 CFR
2011-04-01
... 23 Highways 1 2011-04-01 2011-04-01 false Reimbursement basis. 140.904 Section 140.904 Highways FEDERAL HIGHWAY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION PAYMENT PROCEDURES REIMBURSEMENT... program. (2) Incurred subsequent to the date of authorization by the Federal Highway Administration...
23 CFR 140.904 - Reimbursement basis.
Code of Federal Regulations, 2013 CFR
2013-04-01
... 23 Highways 1 2013-04-01 2013-04-01 false Reimbursement basis. 140.904 Section 140.904 Highways FEDERAL HIGHWAY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION PAYMENT PROCEDURES REIMBURSEMENT... program. (2) Incurred subsequent to the date of authorization by the Federal Highway Administration...
Salary basis of payment for overtime exemption.
Gilliland, J C
1994-07-01
Often employers' problems in complying with the Fair Labor Standards Act salary basis of payment rules arise from their paid time off policies. Although it is possible to write policies that apply to both exempt and nonexempt employees, such policies are complex, and agencies may need to review their compliance with these rules.
Code of Federal Regulations, 2010 CFR
2010-10-01
... 42 Public Health 2 2010-10-01 2010-10-01 false Basis. 405.500 Section 405.500 Public Health CENTERS FOR MEDICARE & MEDICAID SERVICES, DEPARTMENT OF HEALTH AND HUMAN SERVICES MEDICARE PROGRAM FEDERAL HEALTH INSURANCE FOR THE AGED AND DISABLED Criteria for Determining Reasonable Charges § 405.500...
340 waste handling facility interim safety basis
VAIL, T.S.
1999-04-01
This document presents an interim safety basis for the 340 Waste Handling Facility classifying the 340 Facility as a Hazard Category 3 facility. The hazard analysis quantifies the operating safety envelop for this facility and demonstrates that the facility can be operated without a significant threat to onsite or offsite people.
Code of Federal Regulations, 2013 CFR
2013-01-01
... Space Launch Act of 1984, and applicable treaties and international agreements to which the United... 14 Aeronautics and Space 4 2013-01-01 2013-01-01 false Basis. 400.1 Section 400.1 Aeronautics and Space COMMERCIAL SPACE TRANSPORTATION, FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF...
Code of Federal Regulations, 2012 CFR
2012-01-01
... Space Launch Act of 1984, and applicable treaties and international agreements to which the United... 14 Aeronautics and Space 4 2012-01-01 2012-01-01 false Basis. 400.1 Section 400.1 Aeronautics and Space COMMERCIAL SPACE TRANSPORTATION, FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF...
Code of Federal Regulations, 2014 CFR
2014-01-01
... Space Launch Act of 1984, and applicable treaties and international agreements to which the United... 14 Aeronautics and Space 4 2014-01-01 2014-01-01 false Basis. 400.1 Section 400.1 Aeronautics and Space COMMERCIAL SPACE TRANSPORTATION, FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF...
Code of Federal Regulations, 2011 CFR
2011-01-01
... Space Launch Act of 1984, and applicable treaties and international agreements to which the United... 14 Aeronautics and Space 4 2011-01-01 2011-01-01 false Basis. 400.1 Section 400.1 Aeronautics and Space COMMERCIAL SPACE TRANSPORTATION, FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF...
Code of Federal Regulations, 2010 CFR
2010-01-01
... Space Launch Act of 1984, and applicable treaties and international agreements to which the United... 14 Aeronautics and Space 4 2010-01-01 2010-01-01 false Basis. 400.1 Section 400.1 Aeronautics and Space COMMERCIAL SPACE TRANSPORTATION, FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF...
340 Waste handling facility interim safety basis
Stordeur, R.T.
1996-10-04
This document presents an interim safety basis for the 340 Waste Handling Facility classifying the 340 Facility as a Hazard Category 3 facility. The hazard analysis quantifies the operating safety envelop for this facility and demonstrates that the facility can be operated without a significant threat to onsite or offsite people.
The molecular basis of peanut allergy
Technology Transfer Automated Retrieval System (TEKTRAN)
Peanut allergens can trigger a potent and sometimes dangerous immune response in an increasing number of people. The molecular structures of these allergens form the basis for understanding this response. This review describes the currently known peanut allergen structures, and discusses how modif...
Code of Federal Regulations, 2010 CFR
2010-10-01
... Providers § 433.300 Basis. This subpart implements— (a) Section 1903(d)(2)(A) of the Act, which directs that quarterly Federal payments to the States under title XIX (Medicaid) of the Act are to be reduced or... made. (b) Section 1903(d)(2) (C) and (D) of the Act, which provides that a State has 60 days...
29 CFR 541.602 - Salary basis.
Code of Federal Regulations, 2011 CFR
2011-07-01
... quantity of the work performed. Subject to the exceptions provided in paragraph (b) of this section, an exempt employee must receive the full salary for any week in which the employee performs any work without... they perform no work. An employee is not paid on a salary basis if deductions from the...
Code of Federal Regulations, 2014 CFR
2014-10-01
... CENTERS FOR MEDICARE & MEDICAID SERVICES, DEPARTMENT OF HEALTH AND HUMAN SERVICES MEDICARE PROGRAM FEDERAL... Services § 405.2400 Basis. Subpart X is based on the provisions of the following sections of the Act: (a... health clinic services and Federally qualified health center services covered by the Medicare program....
Code of Federal Regulations, 2014 CFR
2014-10-01
... than 65 years; State residence requirements excluding individuals who reside in the State; and... ASSISTANCE PROGRAMS ELIGIBILITY IN GUAM, PUERTO RICO, AND THE VIRGIN ISLANDS General Provisions and Definitions § 436.2 Basis. This part implements the following sections of the Act and public laws that...
42 CFR 438.600 - Statutory basis.
Code of Federal Regulations, 2010 CFR
2010-10-01
... 42 Public Health 4 2010-10-01 2010-10-01 false Statutory basis. 438.600 Section 438.600 Public Health CENTERS FOR MEDICARE & MEDICAID SERVICES, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED.... This subpart is based on sections 1902(a)(4), 1902(a)(19), 1903(m), and 1932(d)(1) of the Act....
Code of Federal Regulations, 2010 CFR
2010-04-01
... CONSUMPTION HAZARD ANALYSIS AND CRITICAL CONTROL POINT (HACCP) SYSTEMS General Provisions § 120.9 Legal basis. Failure of a processor to have and to implement a Hazard Analysis and Critical Control Point (HACCP) system that complies with §§ 120.6, 120.7, and 120.8, or otherwise to operate in accordance with...
Code of Federal Regulations, 2011 CFR
2011-04-01
... CONSUMPTION HAZARD ANALYSIS AND CRITICAL CONTROL POINT (HACCP) SYSTEMS General Provisions § 120.9 Legal basis. Failure of a processor to have and to implement a Hazard Analysis and Critical Control Point (HACCP) system that complies with §§ 120.6, 120.7, and 120.8, or otherwise to operate in accordance with...
THE METABOLIC BASIS OF ARSENIC TOXICITY
The Metabolic Basis of Arsenic Toxicity
David J. Thomas, Experimental Toxicology Division, National Health and Environmental Effects Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, NC
Methylati...
PRELIMINARY SELECTION OF MGR DESIGN BASIS EVENTS
J.A. Kappes
1999-09-16
The purpose of this analysis is to identify the preliminary design basis events (DBEs) for consideration in the design of the Monitored Geologic Repository (MGR). For external events and natural phenomena (e.g., earthquake), the objective is to identify those initiating events that the MGR will be designed to withstand. Design criteria will ensure that radiological release scenarios resulting from these initiating events are beyond design basis (i.e., have a scenario frequency less than once per million years). For internal (i.e., human-induced and random equipment failures) events, the objective is to identify credible event sequences that result in bounding radiological releases. These sequences will be used to establish the design basis criteria for MGR structures, systems, and components (SSCs) design basis criteria in order to prevent or mitigate radiological releases. The safety strategy presented in this analysis for preventing or mitigating DBEs is based on the preclosure safety strategy outlined in ''Strategy to Mitigate Preclosure Offsite Exposure'' (CRWMS M&O 1998f). DBE analysis is necessary to provide feedback and requirements to the design process, and also to demonstrate compliance with proposed 10 CFR 63 (Dyer 1999b) requirements. DBE analysis is also required to identify and classify the SSCs that are important to safety (ITS).
The Contextualist Basis of Scientific Explanation
NASA Astrophysics Data System (ADS)
Guo, Guichun
2014-03-01
From perspectives of contextual structure, elements and features, this paper analyses the contextualist basis of scientific explanation. It is articulated that contextual analysis specifies the boundary conditions of syntactics, semantics, and pragmatics, clarifies the essence and value-orientation, constructs a conversational platform, and unveils the progress condition and historical continuity of scientific explanation.
[Neurocybernetic basis of hallucinations and related illusions].
Pfeiffer, A
1977-03-01
Present concepts of circuits of neurons involved in the development of regular perception are used as a basis for discussing possible processes proceeding in these circuits and producing hallucinations and other illusions and false perceptions in mental patients or normal subjects.
42 CFR 408.200 - Statutory basis.
Code of Federal Regulations, 2014 CFR
2014-10-01
... Health CENTERS FOR MEDICARE & MEDICAID SERVICES, DEPARTMENT OF HEALTH AND HUMAN SERVICES MEDICARE PROGRAM... § 408.200 Statutory basis. This subpart implements provisions of section 1839(e) of the Social Security Act that allow State or local government agencies to enter into an agreement with the Secretary to...
Re-Setting Music Education's "Default Settings"
ERIC Educational Resources Information Center
Regelski, Thomas A.
2013-01-01
This paper explores the effects and problems of one highly influential default setting of the "normal style template" of music education and proposes some alternatives. These do not require abandoning all traditional templates for school music. But re-setting the default settings does depend on reconsidering the promised function of…
System Design and the Safety Basis
Ellingson, Darrel
2008-05-06
The objective of this paper is to present the Bechtel Jacobs Company, LLC (BJC) Lessons Learned for system design as it relates to safety basis documentation. BJC has had to reconcile incomplete or outdated system description information with current facility safety basis for a number of situations in recent months. This paper has relevance in multiple topical areas including documented safety analysis, decontamination & decommissioning (D&D), safety basis (SB) implementation, safety and design integration, potential inadequacy of the safety analysis (PISA), technical safety requirements (TSR), and unreviewed safety questions. BJC learned that nuclear safety compliance relies on adequate and well documented system design information. A number of PIS As and TSR violations occurred due to inadequate or erroneous system design information. As a corrective action, BJC assessed the occurrences caused by systems design-safety basis interface problems. Safety systems reviewed included the Molten Salt Reactor Experiment (MSRE) Fluorination System, K-1065 fire alarm system, and the K-25 Radiation Criticality Accident Alarm System. The conclusion was that an inadequate knowledge of system design could result in continuous non-compliance issues relating to nuclear safety. This was especially true with older facilities that lacked current as-built drawings coupled with the loss of 'historical knowledge' as personnel retired or moved on in their careers. Walkdown of systems and the updating of drawings are imperative for nuclear safety compliance. System design integration with safety basis has relevance in the Department of Energy (DOE) complex. This paper presents the BJC Lessons Learned in this area. It will be of benefit to DOE contractors that manage and operate an aging population of nuclear facilities.
Theory for long time polymer and protein dynamics: Basis functions and time correlation functions
NASA Astrophysics Data System (ADS)
Tang, Wilfred H.; Chang, Xiao-yan; Freed, Karl F.
1995-12-01
We develop methods for alleviating the major impediment in the extension to larger and more complex systems of our matrix method theory for describing the long time dynamics of flexible polymers and proteins in solution. This impediment is associated with the enormous growth in size of the required basis set with the addition of higher order mode coupling basis functions, which are needed to describe the influence on the dynamics of the ``internal friction,'' or equivalently of the memory function matrices. We use the first order eigenfunctions (the generalized Rouse modes) to construct an approximate mode coupling basis. Specific applications are made to united atom models of alkanes with a white noise structureless solvent, where the theory is compared with Brownian dynamics simulations to provide a no-parameter stringent test of the theory. Good convergence is found to the full second order treatment with the new basis set whose size scales more nearly with the size of the system rather than the cube of the system with the previous full basis. These technical improvements enable us to test the need for third order contributions to the dynamics of the longer alkanes and to compute the orientational time correlation functions probed by fluorescence depolarization and NMR experiments. Additional symmetry considerations provide further reductions in the required basis set sizes.
Student learning of basis, span and linear independence in linear algebra
NASA Astrophysics Data System (ADS)
Stewart, Sepideh; Thomas, Michael O. J.
2010-03-01
One of the earlier, more challenging concepts in linear algebra at university is that of basis. Students are often taught procedurally how to find a basis for a subspace using matrix manipulation, but may struggle with understanding the construct of basis, making further progress harder. We believe one reason for this is because students have major difficulties with concepts of span and linear independence which form the requirements for a set of vectors to form a basis. In this research we applied a theoretical framework based on Tall's three worlds of mathematics learning and action-process-object-schema (APOS) theory to the learning of the concept of basis by a group of second year university students. The results suggest that an emphasis on matrix processes may not help students understand the concept, and embodied, visual ideas that could be valuable were usually lacking.
75 FR 75896 - Basis Reporting by Securities Brokers and Basis Determination for Stock
Federal Register 2010, 2011, 2012, 2013, 2014
2010-12-07
... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF THE TREASURY Internal Revenue Service 26 CFR 1 RIN 1545-BI66 Basis Reporting by Securities Brokers and Basis Determination for Stock Correction In rule document 2010-25504 beginning on page 64072 in the issue of...
75 FR 6166 - Basis Reporting by Securities Brokers and Basis Determination for Stock
Federal Register 2010, 2011, 2012, 2013, 2014
2010-02-08
... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF THE TREASURY Internal Revenue Service 26 CFR Parts, 1, 31, and 301 RIN 1545-Bl66 Basis Reporting by Securities Brokers and Basis Determination for Stock Correction In proposed rule document E9-29855 beginning on...
Radial sets: interactive visual analysis of large overlapping sets.
Alsallakh, Bilal; Aigner, Wolfgang; Miksch, Silvia; Hauser, Helwig
2013-12-01
In many applications, data tables contain multi-valued attributes that often store the memberships of the table entities to multiple sets such as which languages a person masters, which skills an applicant documents, or which features a product comes with. With a growing number of entities, the resulting element-set membership matrix becomes very rich of information about how these sets overlap. Many analysis tasks targeted at set-typed data are concerned with these overlaps as salient features of such data. This paper presents Radial Sets, a novel visual technique to analyze set memberships for a large number of elements. Our technique uses frequency-based representations to enable quickly finding and analyzing different kinds of overlaps between the sets, and relating these overlaps to other attributes of the table entities. Furthermore, it enables various interactions to select elements of interest, find out if they are over-represented in specific sets or overlaps, and if they exhibit a different distribution for a specific attribute compared to the rest of the elements. These interactions allow formulating highly-expressive visual queries on the elements in terms of their set memberships and attribute values. As we demonstrate via two usage scenarios, Radial Sets enable revealing and analyzing a multitude of overlapping patterns between large sets, beyond the limits of state-of-the-art techniques. PMID:24051816
Safety basis academy summary of project implementation from 2007-2009
Johnston, Julie A
2009-01-01
During fiscal years 2007 through 2009, in accordance with Performance Based Incentives with DOE/NNSA Los Alamos Site Office, Los Alamos National Security (LANS) implemented and operated a Safety Basis Academy (SBA) to facilitate uniformity in technical qualifications of safety basis professionals across the nuclear weapons complex. The implementation phase of the Safety Basis Academy required development, delivery, and finalizing a set of 23 courses. The courses developed are capable of supporting qualification efforts for both federal and contractor personnel throughout the DOE/NNSA Complex. The LANS Associate Director for Nuclear and High Hazard Operations (AD-NHHO) delegated project responsibillity to the Safety Basis Division. The project was assigned to the Safety Basis Technical Services (SB-TS) Group at Los Alamos National Laboratory (LANL). The main tasks were project needs analysis, design, development, implementation of instructional delivery, and evaluation of SBA courses. DOE/NNSA responsibility for oversight of the SBA project was assigned to the Chief of Defense for Nuclear Safety, and delegated to the Authorization Basis Senior Advisor, Continuous Learning Chair (CDNS-ABSA/CLC). NNSA developed a memorandum of agreement with LANS AD-NHHO. Through a memorandum of agreement initiated by NNSA, the DOE National Training Center (NTC) will maintain the set of Safety Basis Academy courses and is able to facilitate course delivery throughout the DOE Complex.
Multi-level basis selection of wavelet packet decomposition tree for heart sound classification.
Safara, Fatemeh; Doraisamy, Shyamala; Azman, Azreen; Jantan, Azrul; Abdullah Ramaiah, Asri Ranga
2013-10-01
Wavelet packet transform decomposes a signal into a set of orthonormal bases (nodes) and provides opportunities to select an appropriate set of these bases for feature extraction. In this paper, multi-level basis selection (MLBS) is proposed to preserve the most informative bases of a wavelet packet decomposition tree through removing less informative bases by applying three exclusion criteria: frequency range, noise frequency, and energy threshold. MLBS achieved an accuracy of 97.56% for classifying normal heart sound, aortic stenosis, mitral regurgitation, and aortic regurgitation. MLBS is a promising basis selection to be suggested for signals with a small range of frequencies.
MOTIVATION: Goals and Goal Setting
ERIC Educational Resources Information Center
Stratton, Richard K.
2005-01-01
Goal setting has great impact on a team's performance. Goals enable a team to synchronize their efforts to achieve success. In this article, the author talks about goals and goal setting. This articles complements Domain 5--Teaching and Communication (p.14) and discusses one of the benchmarks listed therein: "Teach the goal setting process and…
Motivating Athletes Through Goal Setting.
ERIC Educational Resources Information Center
Weinberg, Robert S.
1982-01-01
This article provides some guidelines for coaches and athletes for goal setting strategies: (1) set realistic goals; (2) write down goals, so that they are remembered and understood by all persons involved; (3) set measurable objective goals; and (4) have coach act as facilitator. (CJ)
Fuzzy Sets and Mathematical Education.
ERIC Educational Resources Information Center
Alsina, C.; Trillas, E.
1991-01-01
Presents the concept of "Fuzzy Sets" and gives some ideas for its potential interest in mathematics education. Defines what a Fuzzy Set is, describes why we need to teach fuzziness, gives some examples of fuzzy questions, and offers some examples of activities related to fuzzy sets. (MDH)
42 CFR 409.1 - Statutory basis.
Code of Federal Regulations, 2010 CFR
2010-10-01
... part is based on the identified provisions of the following sections of the Social Security Act: (a... sets forth the rules for individuals who have end-stage renal disease (ESRD), for organ donors, and...
The biochemical basis of hereditary fructose intolerance.
Bouteldja, Nadia; Timson, David J
2010-04-01
Hereditary fructose intolerance is a rare, but potentially lethal, inherited disorder of fructose metabolism, caused by mutation of the aldolase B gene. Treatment currently relies solely on dietary restriction of problematic sugars. Biochemical study of defective aldolase B enzymes is key to revealing the molecular basis of the disease and providing a stronger basis for improved treatment and diagnosis. Such studies have revealed changes in enzyme activity, stability and oligomerisation. However, linking these changes to disease phenotypes has not always been straightforward. This review gives a general overview of the features of hereditary fructose intolerance, then concentrates on the biochemistry of the AP variant (Ala149Pro variant of aldolase B) and molecular pathological consequences of mutation of the aldolase B gene.
Radioactive Waste Management BasisApril 2006
Perkins, B K
2011-08-31
This Radioactive Waste Management Basis (RWMB) documents radioactive waste management practices adopted at Lawrence Livermore National Laboratory (LLNL) pursuant to Department of Energy (DOE) Order 435.1, Radioactive Waste Management. The purpose of this Radioactive Waste Management Basis is to describe the systematic approach for planning, executing, and evaluating the management of radioactive waste at LLNL. The implementation of this document will ensure that waste management activities at LLNL are conducted in compliance with the requirements of DOE Order 435.1, Radioactive Waste Management, and the Implementation Guide for DOE Manual 435.1-1, Radioactive Waste Management Manual. Technical justification is provided where methods for meeting the requirements of DOE Order 435.1 deviate from the DOE Manual 435.1-1 and Implementation Guide.
Genetic basis of human brain evolution
Vallender, Eric J.; Mekel-Bobrov, Nitzan; Lahn, Bruce T.
2009-01-01
Human evolution is characterized by a rapid increase in brain size and complexity. Decades of research have made important strides in identifying anatomical and physiological substrates underlying the unique features of the human brain. By contrast, it has become possible only very recently to examine the genetic basis of human brain evolution. Through comparative genomics, tantalizing insights regarding human brain evolution have emerged. The genetic changes that potentially underlie human brain evolution span a wide range from single nucleotide substitutions to large-scale structural alterations of the genome. Similarly, the functional consequences of these genetic changes vary greatly, including protein-sequence alterations, cis-regulatory changes and even the emergence of new genes and the extinction of existing ones. Here, we provide a general review of recent findings into the genetic basis of human brain evolution, highlight the most notable trends that have emerged and caution against overinterpretation of current data. PMID:18848363
TECHNICAL BASIS DOCUMENT FOR NATURAL EVENT HAZARDS
KRIPPS, L.J.
2006-07-31
This technical basis document was developed to support the documented safety analysis (DSA) and describes the risk binning process and the technical basis for assigning risk bins for natural event hazard (NEH)-initiated accidents. The purpose of the risk binning process is to determine the need for safety-significant structures, systems, and components (SSC) and technical safety requirement (TSR)-level controls for a given representative accident or represented hazardous conditions based on an evaluation of the frequency and consequence. Note that the risk binning process is not applied to facility workers, because all facility worker hazardous conditions are considered for safety-significant SSCs and/or TSR-level controls.
High Scores at BASIS Charter Schools
ERIC Educational Resources Information Center
Kronholz, June
2014-01-01
While U.S. schools struggled to reach even an average score on a key international exam for 15-year-olds in 2012, BASIS Tucson North, an economically modest, ethnically diverse charter school in Arizona, outperformed every country in the world, and left even Shanghai, China's academic gem in the dust. With the U.S. frantic about its place in…
Minimal Basis for Gauge Theory Amplitudes
Bjerrum-Bohr, N. E. J.; Damgaard, Poul H.; Vanhove, Pierre
2009-10-16
Identities based on monodromy for integrations in string theory are used to derive relations between different color-ordered tree-level amplitudes in both bosonic and supersymmetric string theory. These relations imply that the color-ordered tree-level n-point gauge theory amplitudes can be expanded in a minimal basis of (n-3)exclamation amplitudes. This result holds for any choice of polarizations of the external states and in any number of dimensions.
A Genetic Basis for Motivated Exercise.
Good, Deborah J; Li, Mengjiao; Deater-Deckard, Kirby
2015-10-01
Prior research has demonstrated a genetic basis for motivated exercise, with evidence of a role for nescient helix-loop-helix-2 (NHLH2/Nhlh2). Nhlh2 transcriptionally regulates the monoamine oxidase A (MAO-A) gene. This article examines the evidence for the hypothesis that polymorphisms in NHLH2 or MAO-A contribute to differences in the human motivation for exercise and physical activity. The genetic pathways that link exercise and motivation are discussed. PMID:26196864
The basis spline method and associated techniques
Bottcher, C.; Strayer, M.R.
1989-01-01
We outline the Basis Spline and Collocation methods for the solution of Partial Differential Equations. Particular attention is paid to the theory of errors, and the handling of non-self-adjoint problems which are generated by the collocation method. We discuss applications to Poisson's equation, the Dirac equation, and the calculation of bound and continuum states of atomic and nuclear systems. 12 refs., 6 figs.
The molecular basis for novel therapies.
Hu, Jethro; Kesari, Santosh
2012-01-01
The era of targeted therapy for glioblastoma has arrived, but results have been modest thus far. This review highlights the challenges inherent to treating glioblastoma with targeted therapy and delves into the complex signaling networks that form the molecular basis of novel therapies. Past failures, current challenges, and future possibilities are discussed in the context of the classic "oncogenic" signaling network, as well as the "nononcogenic" stress response network.
A Genetic Basis for Motivated Exercise.
Good, Deborah J; Li, Mengjiao; Deater-Deckard, Kirby
2015-10-01
Prior research has demonstrated a genetic basis for motivated exercise, with evidence of a role for nescient helix-loop-helix-2 (NHLH2/Nhlh2). Nhlh2 transcriptionally regulates the monoamine oxidase A (MAO-A) gene. This article examines the evidence for the hypothesis that polymorphisms in NHLH2 or MAO-A contribute to differences in the human motivation for exercise and physical activity. The genetic pathways that link exercise and motivation are discussed.
Neurons with radial basis like rate functions.
Kovács, Zsolt László
2005-01-01
Artificial neural networks constructed with "locally tuned processing units" and more generally referred to as "radial basis function networks" have been proposed by a number of workers. In this communication, I submit a conjecture, based on indirect experimental and direct computational evidence of the Hodgkin-Huxley model, that there may be biological neurons in nervous systems for which the rate function is locally tuned. If proved to be valid, this conjecture may simplify neurodynamic models of some functions of nervous systems.
Observation Instrument of Play Behaviour in a Classroom Setting
ERIC Educational Resources Information Center
Berkhout, Louise; Hoekman, Joop; Goorhuis-Brouwer, Sieneke M.
2012-01-01
The objective of this study was to develop an instrument to observe the play behaviour of a whole group of children from four to six years of age in a classroom setting on the basis of video recording. The instrument was developed in collaboration with experienced teachers and experts on play. Categories of play were derived from the literature…
Object Representations Maintain Attentional Control Settings across Space and Time
ERIC Educational Resources Information Center
Schreij, Daniel; Olivers, Christian N. L.
2009-01-01
Previous research has revealed that we create and maintain mental representations for perceived objects on the basis of their spatiotemporal continuity. An important question is what type of information can be maintained within these so-called object files. We provide evidence that object files retain specific attentional control settings for…
Dissociating Stimulus-Set and Response-Set in the Context of Task-Set Switching
ERIC Educational Resources Information Center
Kieffaber, Paul D.; Kruschke, John K.; Cho, Raymond Y.; Walker, Philip M.; Hetrick, William P.
2013-01-01
The primary aim of the present research was to determine how "stimulus-set" and "response-set" components of task-set contribute to switch costs and conflict processing. Three experiments are described wherein participants completed an explicitly cued task-switching procedure. Experiment 1 established that task switches requiring a reconfiguration…
Cross Validation of Job Families Using an Expanded Data Set. USES Test Research Report No. 53.
ERIC Educational Resources Information Center
Swarthout, David
The analyses of J. E. Hunter (1983) were replicated with an expanded data set. The Hunter study, the basis of the Validity Generalization system used by the United States Employment Service, contained 515 General Aptitude Test Battery validation studies. The data set in this study included these and additional studies to bring the data set to 755…
40 CFR 791.40 - Basis for the proposed order.
Code of Federal Regulations, 2010 CFR
2010-07-01
... CONTROL ACT (CONTINUED) DATA REIMBURSEMENT Basis for Proposed Order § 791.40 Basis for the proposed order... other basis for allocation if necessary. Additional factors that may be taken into account include,...
The genetic basis of laboratory adaptation in Caulobacter crescentus.
Marks, Melissa E; Castro-Rojas, Cyd Marie; Teiling, Clotilde; Du, Lei; Kapatral, Vinayak; Walunas, Theresa L; Crosson, Sean
2010-07-01
The dimorphic bacterium Caulobacter crescentus has evolved marked phenotypic changes during its 50-year history of culture in the laboratory environment, providing an excellent system for the study of natural selection and phenotypic microevolution in prokaryotes. Combining whole-genome sequencing with classical molecular genetic tools, we have comprehensively mapped a set of polymorphisms underlying multiple derived phenotypes, several of which arose independently in separate strain lineages. The genetic basis of phenotypic differences in growth rate, mucoidy, adhesion, sedimentation, phage susceptibility, and stationary-phase survival between C. crescentus strain CB15 and its derivative NA1000 is determined by coding, regulatory, and insertion/deletion polymorphisms at five chromosomal loci. This study evidences multiple genetic mechanisms of bacterial evolution as driven by selection for growth and survival in a new selective environment and identifies a common polymorphic locus, zwf, between lab-adapted C. crescentus and clinical isolates of Pseudomonas aeruginosa that have adapted to a human host during chronic infection.
Basis for selecting optimum antibiotic regimens for secondary peritonitis.
Maseda, Emilio; Gimenez, Maria-Jose; Gilsanz, Fernando; Aguilar, Lorenzo
2016-01-01
Adequate management of severely ill patients with secondary peritonitis requires supportive therapy of organ dysfunction, source control of infection and antimicrobial therapy. Since secondary peritonitis is polymicrobial, appropriate empiric therapy requires combination therapy in order to achieve the needed coverage for both common and more unusual organisms. This article reviews etiological agents, resistance mechanisms and their prevalence, how and when to cover them and guidelines for treatment in the literature. Local surveillances are the basis for the selection of compounds in antibiotic regimens, which should be further adapted to the increasing number of patients with risk factors for resistance (clinical setting, comorbidities, previous antibiotic treatments, previous colonization, severity…). Inadequate antimicrobial regimens are strongly associated with unfavorable outcomes. Awareness of resistance epidemiology and of clinical consequences of inadequate therapy against resistant bacteria is crucial for clinicians treating secondary peritonitis, with delicate balance between optimization of empirical therapy (improving outcomes) and antimicrobial overuse (increasing resistance emergence).
An incremental design of radial basis function networks.
Yu, Hao; Reiner, Philip D; Xie, Tiantian; Bartczak, Tomasz; Wilamowski, Bogdan M
2014-10-01
This paper proposes an offline algorithm for incrementally constructing and training radial basis function (RBF) networks. In each iteration of the error correction (ErrCor) algorithm, one RBF unit is added to fit and then eliminate the highest peak (or lowest valley) in the error surface. This process is repeated until a desired error level is reached. Experimental results on real world data sets show that the ErrCor algorithm designs very compact RBF networks compared with the other investigated algorithms. Several benchmark tests such as the duplicate patterns test and the two spiral problem were applied to show the robustness of the ErrCor algorithm. The proposed ErrCor algorithm generates very compact networks. This compactness leads to greatly reduced computation times of trained networks.
Molecular basis for chromatin binding and regulation of MLL5.
Ali, Muzaffar; Rincón-Arano, Héctor; Zhao, Wei; Rothbart, Scott B; Tong, Qiong; Parkhurst, Susan M; Strahl, Brian D; Deng, Lih-Wen; Groudine, Mark; Kutateladze, Tatiana G
2013-07-01
The human mixed-lineage leukemia 5 (MLL5) protein mediates hematopoietic cell homeostasis, cell cycle, and survival; however, the molecular basis underlying MLL5 activities remains unknown. Here, we show that MLL5 is recruited to gene-rich euchromatic regions via the interaction of its plant homeodomain finger with the histone mark H3K4me3. The 1.48-Å resolution crystal structure of MLL5 plant homeodomain in complex with the H3K4me3 peptide reveals a noncanonical binding mechanism, whereby K4me3 is recognized through a single aromatic residue and an aspartate. The binding induces a unique His-Asp swapping rearrangement mediated by a C-terminal α-helix. Phosphorylation of H3T3 and H3T6 abrogates the association with H3K4me3 in vitro and in vivo, releasing MLL5 from chromatin in mitosis. This regulatory switch is conserved in the Drosophila ortholog of MLL5, UpSET, and suggests the developmental control for targeting of H3K4me3. Together, our findings provide first insights into the molecular basis for the recruitment, exclusion, and regulation of MLL5 at chromatin. PMID:23798402
Molecular basis for chromatin binding and regulation of MLL5
Ali, Muzaffar; Rincón-Arano, Héctor; Zhao, Wei; Rothbart, Scott B.; Tong, Qiong; Parkhurst, Susan M.; Strahl, Brian D.; Deng, Lih-Wen; Groudine, Mark; Kutateladze, Tatiana G.
2013-01-01
The human mixed-lineage leukemia 5 (MLL5) protein mediates hematopoietic cell homeostasis, cell cycle, and survival; however, the molecular basis underlying MLL5 activities remains unknown. Here, we show that MLL5 is recruited to gene-rich euchromatic regions via the interaction of its plant homeodomain finger with the histone mark H3K4me3. The 1.48-Å resolution crystal structure of MLL5 plant homeodomain in complex with the H3K4me3 peptide reveals a noncanonical binding mechanism, whereby K4me3 is recognized through a single aromatic residue and an aspartate. The binding induces a unique His–Asp swapping rearrangement mediated by a C-terminal α-helix. Phosphorylation of H3T3 and H3T6 abrogates the association with H3K4me3 in vitro and in vivo, releasing MLL5 from chromatin in mitosis. This regulatory switch is conserved in the Drosophila ortholog of MLL5, UpSET, and suggests the developmental control for targeting of H3K4me3. Together, our findings provide first insights into the molecular basis for the recruitment, exclusion, and regulation of MLL5 at chromatin. PMID:23798402
PUMP SETS NO. 5 AND NO. 4. Each pump set ...
PUMP SETS NO. 5 AND NO. 4. Each pump set consists of a Worthington Pump and a General Electric motor - Edwards Air Force Base, Air Force Rocket Propulsion Laboratory, Flame Deflector Water System, Test Area 1-120, north end of Jupiter Boulevard, Boron, Kern County, CA
Neurobiological Basis of Language Learning Difficulties.
Krishnan, Saloni; Watkins, Kate E; Bishop, Dorothy V M
2016-09-01
In this paper we highlight why there is a need to examine subcortical learning systems in children with language impairment and dyslexia, rather than focusing solely on cortical areas relevant for language. First, behavioural studies find that children with these neurodevelopmental disorders perform less well than peers on procedural learning tasks that depend on corticostriatal learning circuits. Second, fMRI studies in neurotypical adults implicate corticostriatal and hippocampal systems in language learning. Finally, structural and functional abnormalities are seen in the striatum in children with language disorders. Studying corticostriatal networks in developmental language disorders could offer us insights into their neurobiological basis and elucidate possible modes of compensation for intervention. PMID:27422443
Anatomical basis for Wilms tumor surgery
Tröbs, R. B.
2009-01-01
Wilms tumor surgery requires meticulous planning and sophisticated surgical technique. Detailed anatomical knowledge can facilitate the uneventful performance of tumor nephrectomy and cannot be replaced by advanced and sophisticated imaging techniques. We can define two main goals for surgery: (1) exact staging as well as (2) safe and complete resection of tumor without spillage. This review aims to review the anatomical basis for Wilms tumor surgery. It focuses on the surgical anatomy of retroperitoneal space, aorta, vena cava and their large branches with lymphatics. Types and management of vascular injuries are discussed. PMID:20671845
Chopped random-basis quantum optimization
Caneva, Tommaso; Calarco, Tommaso; Montangero, Simone
2011-08-15
In this work, we describe in detail the chopped random basis (CRAB) optimal control technique recently introduced to optimize time-dependent density matrix renormalization group simulations [P. Doria, T. Calarco, and S. Montangero, Phys. Rev. Lett. 106, 190501 (2011)]. Here, we study the efficiency of this control technique in optimizing different quantum processes and we show that in the considered cases we obtain results equivalent to those obtained via different optimal control methods while using less resources. We propose the CRAB optimization as a general and versatile optimal control technique.
The Cellular Basis of a Corollary Discharge
NASA Astrophysics Data System (ADS)
Poulet, James F. A.; Hedwig, Berthold
2006-01-01
How do animals discriminate self-generated from external stimuli during behavior and prevent desensitization of their sensory pathways? A fundamental concept in neuroscience states that neural signals, termed corollary discharges or efference copies, are forwarded from motor to sensory areas. Neurons mediating these signals have proved difficult to identify. We show that a single, multisegmental interneuron is responsible for the pre- and postsynaptic inhibition of auditory neurons in singing crickets (Gryllus bimaculatus). Therefore, this neuron represents a corollary discharge interneuron that provides a neuronal basis for the central control of sensory responses.