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1

Near Earth Objects Program: Orbit Diagrams  

NSDL National Science Digital Library

This page provides access to diagrams of the orbits of a very large number of objects in the asteroid belt as well as comets that cross Earth's orbit. The collection is searchable by object name or designation and users can also browse through an extensive list of potentially hazardous asteroids.

NASA JPL Near Earth Object Program

2

Definition of molecular orbitals in fragment molecular orbital method  

NASA Astrophysics Data System (ADS)

We propose an explicit definition of molecular orbitals in the fragment molecular orbital (FMO) method. We evaluated the accuracy of this method by using a conventional MO method and the FMO method to compare the calculated molecular orbitals and their orbital energies for four poly glycine molecules. These comparisons show that the molecular orbitals and their orbital energies calculated with the FMO method are within about 1% difference of those calculated with the conventional method. Therefore, the molecular orbitals calculated with the FMO method can be used for accurate calculations of chemical properties of large molecules.

Inadomi, Yuichi; Nakano, Tatsuya; Kitaura, Kazuo; Nagashima, Umpei

2002-09-01

3

ISS EPS Orbital Replacement Unit Block Diagrams  

NASA Technical Reports Server (NTRS)

The attached documents are being provided to Switching Power Magazine for information purposes. This magazine is writing a feature article on the International Space Station Electrical Power System, focusing on the switching power processors. These units include the DC-DC Converter Unit (DDCU), the Bi-directional Charge/Discharge Unit (BCDU), and the Sequential Shunt Unit (SSU). These diagrams are high-level schematics/block diagrams depicting the overall functionality of each unit.

Schmitz, Gregory V.

2001-01-01

4

Some Observations on Molecular Orbital Theory  

ERIC Educational Resources Information Center

A few flawed predictions in the context of homonuclear diatomic molecules are presented in order to introduce students to molecular orbital (MO) theory. A common misrepresentation of the relationship between the energy of an atomic orbital and the energy of the MO associated with the atomic orbital is illustrated.

Journal of Chemical Education, 2005

2005-01-01

5

Ab initio molecular crystal structures, spectra, and phase diagrams.  

PubMed

Conspectus Molecular crystals are chemists' solids in the sense that their structures and properties can be understood in terms of those of the constituent molecules merely perturbed by a crystalline environment. They form a large and important class of solids including ices of atmospheric species, drugs, explosives, and even some organic optoelectronic materials and supramolecular assemblies. Recently, surprisingly simple yet extremely efficient, versatile, easily implemented, and systematically accurate electronic structure methods for molecular crystals have been developed. The methods, collectively referred to as the embedded-fragment scheme, divide a crystal into monomers and overlapping dimers and apply modern molecular electronic structure methods and software to these fragments of the crystal that are embedded in a self-consistently determined crystalline electrostatic field. They enable facile applications of accurate but otherwise prohibitively expensive ab initio molecular orbital theories such as Møller-Plesset perturbation and coupled-cluster theories to a broad range of properties of solids such as internal energies, enthalpies, structures, equation of state, phonon dispersion curves and density of states, infrared and Raman spectra (including band intensities and sometimes anharmonic effects), inelastic neutron scattering spectra, heat capacities, Gibbs energies, and phase diagrams, while accounting for many-body electrostatic (namely, induction or polarization) effects as well as two-body exchange and dispersion interactions from first principles. They can fundamentally alter the role of computing in the studies of molecular crystals in the same way ab initio molecular orbital theories have transformed research practices in gas-phase physical chemistry and synthetic chemistry in the last half century. In this Account, after a brief summary of formalisms and algorithms, we discuss applications of these methods performed in our group as compelling illustrations of their unprecedented power in addressing some of the outstanding problems of solid-state chemistry, high-pressure chemistry, or geochemistry. They are the structure and spectra of ice Ih, in particular, the origin of two peaks in the hydrogen-bond-stretching region of its inelastic neutron scattering spectra, a solid-solid phase transition from CO2-I to elusive, metastable CO2-III, pressure tuning of Fermi resonance in solid CO2, and the structure and spectra of solid formic acid, all at the level of second-order Møller-Plesset perturbation theory or higher. PMID:24754304

Hirata, So; Gilliard, Kandis; He, Xiao; Li, Jinjin; Sode, Olaseni

2014-09-16

6

How Different Variants of Orbit Diagrams Influence Student Explanations of the Seasons  

ERIC Educational Resources Information Center

The cause of the seasons is often associated with a very particular alternative conception: That the earth's orbit around the sun is highly elongated, and the differences in distance result in variations in temperature. It has been suggested that the standard diagrams used to depict the earth's orbit may be in some way responsible for the initial…

Lee, Victor R.

2010-01-01

7

Orbiting molecular-beam laboratory  

NASA Technical Reports Server (NTRS)

The composition of the atmosphere within the planned orbital envelope of the Space Shuttle and the velocity necessary to maintain a stable orbit within that envelope provide unique conditions for forming a high-purity, moderate energy beam (about 5 eV) of atomic oxygen. At 500 km, for example, atomic oxygen comprises approximately 90% of the atmosphere. Since the mean thermal speed of the ambient atomic oxygen is substantially less than the orbital speed, a high-purity beam can be generated by sweeping through the gas with a series of beam-forming truncated conical shells. Characteristics of the beam, including energy distribution, flux, and purity variation with orbital altitude and methods for lowering the mean energy, are presented. Gas-surface interaction experiments that have been proposed for this laboratory are also discussed.

Outlaw, R. A.; Brock, F. J.

1977-01-01

8

The Molecular Orbital Theory of Chemical Valency. I. The Determination of Molecular Orbitals  

Microsoft Academic Search

In the molecular orbital theory of valency the electrons are assigned to the whole molecule rather than to atoms or to other localized parts. While the method has advantages in dealing with the properties of a molecule as a whole, such as its energy states, the extension of each orbital over the molecular framework is a disadvantage when dealing with

John Lennard-Jones

1949-01-01

9

Graph theory and molecular orbitals  

Microsoft Academic Search

A simple algorithm for the determination of the number of zeros in the molecular graphs of alternant cata-condensed conjugated hydrocarbons is derived. For non-branched hydrocarbons it is shown that, from the topological point of view, only four types of ring systems exist. The given algorithm enables the derivation of a number of general regularities relating the structural features of the

Dragoš Cvetkovi?; Ivan Gutman; Nenad Trinajsti?

1974-01-01

10

Spin–orbit interaction mediated molecular dissociation  

SciTech Connect

The effect of the spin–orbit interaction to photofragmentation is investigated in the mercury(II) bromide (HgBr{sub 2}) molecule. Changes in the fragmentation between the two spin–orbit components of Hg 5d photoionization, as well as within the molecular-field-splitted levels of these components are observed. Dissociation subsequent to photoionization is studied with synchrotron radiation and photoelectron-photoion coincidence spectroscopy. The experimental results are accompanied by relativistic ab initio analysis of the photoelectron spectrum.

Kokkonen, E., E-mail: esko.kokkonen@oulu.fi; Jänkälä, K.; Kettunen, J. A.; Heinäsmäki, S.; Karpenko, A.; Huttula, M. [Department of Physics, University of Oulu, Box 3000, 90014 Oulu (Finland)] [Department of Physics, University of Oulu, Box 3000, 90014 Oulu (Finland); Löytynoja, T. [Department of Physics, University of Oulu, Box 3000, 90014 Oulu (Finland) [Department of Physics, University of Oulu, Box 3000, 90014 Oulu (Finland); Division of Theoretical Chemistry and Biology, School of Biotechnology, Royal Institute of Technology, S-106 91 Stockholm (Sweden)

2014-05-14

11

Molecular orbital calculations of the electronic structure of borazane  

Microsoft Academic Search

An ab initio molecular orbital calculation of the addition compound of boron hydride and ammonia has been carried out. By expanding the molecular orbitals of the addition compound in terms of the molecular orbitals of boron hydride and of ammonia in a separated state, the origin of charge transfer and bond formation between these two species in the interaction has

Hiroshi Fujimoto; Shigeki Kato; Shinichi Yamabe; Kenichi Fukui

1974-01-01

12

MOPAC: A semiempirical molecular orbital program  

Microsoft Academic Search

Before we start, we need a working definition for MOPAC. The following description has been used many times to describe MOPAC: MOPAC is a general-purpose, semiempirical molecular orbital program for the study of chemical reactions involving molecules, ions, and linear polymers. It implements the semiempirical Hamiltonians MNDO, AM 1, MINDO\\/3, and MNDOPM3, and combir_es the calculations of vibrational spectra, thermodynamic

James J. P. Stewart

1990-01-01

13

Phase diagram of a generalized Hubbard model applied to orbital order in manganites  

NASA Astrophysics Data System (ADS)

The magnetic phase diagram of a two-dimensional generalized Hubbard model proposed for manganites is studied within Hartree-Fock approximation. In this model the hopping matrix includes anisotropic diagonal hopping matrix elements as well as off-diagonal elements. The antiferromagnetic (AF), ferromagnetic (F), canted (C), and paramagnetic (P) states are included in the analysis as possible phases. It is found that away from half-filling only the canted and F states may exist and AF and P states which are possible for the usual Hubbard model do not appear. This is because the F order has already developed for on-site repulsion U=0 due to the hopping matrix of the generalized model. When applied for manganites the orbital degree is described by a pseudospin. Thus our ``magnetic'' phase diagram obtained physically describes how orbital order changes with U and with doping for manganites. Part of our results are consistent with other numerical calculations and some experiments.

Yuan, Qingshan; Yamamoto, Takashi; Thalmeier, Peter

2000-11-01

14

Section 2 Simple Molecular Orbital Theory In this section, the conceptual framework of molecular orbital theory is developed.  

E-print Network

Section 2 Simple Molecular Orbital Theory In this section, the conceptual framework of molecular orbital theory is developed. Applications are presented and problems are given and solved within. Unlike most texts on molecular orbital theory and quantum mechanics, this text treats polyatomic

Simons, Jack

15

A Comparison of Molecular Vibrational Theory to Huckel Molecular Orbital Theory.  

ERIC Educational Resources Information Center

Compares the similar mathematical problems of molecular vibrational calculations (at any intermediate level of sophistication) and molecular orbital calculations (at the Huckel level). Discusses how the generalizations of Huckel treatment of molecular orbitals apply to vibrational theory. (TW)

Keeports, David

1986-01-01

16

Tomographic Imaging of Molecular Orbitals in Length and Velocity Form  

E-print Network

], to the determination of internuclear distances [7, 8]. A new application is the imaging of electronic orbitals usingTomographic Imaging of Molecular Orbitals in Length and Velocity Form Elmar V. van der ZwanGermany Abstract. Recently Itatani et al. [Nature 432, 876 (2004)] introduced the new concept of molecular orbital

Lein, Manfred

17

Fragment molecular orbital method: analytical energy gradients  

NASA Astrophysics Data System (ADS)

The fragment molecular orbital (FMO) method, which aimed to calculate large molecules such as proteins, was proposed in a previous work. The method divides a molecule into small fragments and performs MO calculations on the fragments and the fragment pairs to obtain the total energy of molecule. The method with the analytical energy gradient at the HF level of theory has been incorporated into the G AUSSIAN 94 (G94) package. Geometry optimization calculations using the energy gradients were successfully performed on a model peptide, methyl-capped glycine trimer.

Kitaura, Kazuo; Sugiki, Sin-Ichirou; Nakano, Tatsuya; Komeiji, Yuto; Uebayasi, Masami

2001-03-01

18

Molecular Orbital Animations for Organic Chemistry  

NASA Astrophysics Data System (ADS)

This paper addresses our approach to teaching organic chemistry and introduces the application of highest occupied and lowest unoccupied molecular orbitals (HOMOs and LUMOs) in animated form. This teaching approach allows students to (i) picture the reaction process in three dimensions, (ii) better understand why a reaction occurs by noting electron-rich and electron-poor centers, (iii) see steric arguments in competing reactions, (iv) observe electron flow from the nucleophile into the electrophile, (v) gain a better understanding of resonance and hyperconjugation, and (vi) gain an appreciation for semiempirical and ab initio calculations.

Fleming, Steven A.; Hart, Greg R.; Savage, Paul B.

2000-06-01

19

Rotation and Anisotropic Molecular Orbital Effect in a Single H2TPP Molecule Transistor  

NASA Astrophysics Data System (ADS)

Electron transport through a single molecule is determined not only by the intrinsic properties of the molecule but also by the configuration of the molecule with respect to the lead electrodes. Here, we show how electron transport through a single H2TPP molecule is modulated by changes in the configuration. The Coulomb stability diagram of a single H2TPP molecule transistor exhibited a few different patterns in different measurement scans. Furthermore, the sample exhibited negative differential resistance, the magnitude of which changed with the pattern in the Coulomb stability diagram. Such behavior can be explained by the rotation of the molecule with anisotropic molecular orbitals in the gap electrodes induced by electrical stress. Moreover, we find that the energy separations between molecular orbitals are also affected by the rotation, confirming that the metal-molecule interface configuration renormalizes the electronic levels in the molecule.

Sakata, Shuichi; Yoshida, Kenji; Kitagawa, Yuichi; Ishii, Kazuyuki; Hirakawa, Kazuhiko

2013-12-01

20

Molecular-orbital model for metal-sapphire interfacial strength  

NASA Technical Reports Server (NTRS)

Self-consistent-field X-Alpha scattered-wave cluster molecular-orbital models have been constructed for transition and noble metals (Fe, Ni, Cu, and Ag) in contact with a sapphire (Al2O3) surface. It is found that a chemical bond is established between the metal d-orbital electrons and the nonbonding 2p-orbital electrons of the oxygen anions on the Al2O3 surface. An increasing number of occupied metal-sapphire antibonding molecular orbitals explains qualitatively the observed decrease of contact shear strength through the series Fe, Ni, Cu, and Ag.

Johnson, K. H.; Pepper, S. V.

1982-01-01

21

Periodic orbits of the hydrogen molecular ion and their quantization  

SciTech Connect

In a classical study of the hydrogen molecular ion beyond the Born-Oppenheimer approximation (BOA), we have found that segments of trajectories resemble that of the Born-Oppenheimer approximation periodic orbits. The importance of this fact to the classical understanding of chemical bonding leads us to a systematic study of the periodic orbits of the planar hydrogen molecular ion within the BOA. Besides introducing a classification scheme for periodic orbits, we discuss the convergence properties of families of periodic orbits and their bifurcation patterns according to their types. Semiclassical calculations of the density of states based on these periodic orbits yield results in agreement with the exact quantum eigenvalues of the hydrogen molecular ion system.

Duan, Y.; Yuan, J. [Department of Physics and Atmospheric Science, Drexel University, Philadelphia, Pennsylvania 19104 (United States)] [Department of Physics and Atmospheric Science, Drexel University, Philadelphia, Pennsylvania 19104 (United States); Bao, C. [Department of Physics, Zhongshan University, Guangzhou, 510275 (China)] [Department of Physics, Zhongshan University, Guangzhou, 510275 (China)

1995-11-01

22

Orbits  

NSDL National Science Digital Library

This Topic in Depth explores the Web's offerings on Orbits. The first site is offered by Northwestern University and asks: What is an orbit? (1 ). The site answers questions such as What causes an orbit to happen?, What is a satellite?, What travels in an orbit?, and Are there orbits within orbits?. A great starting site for this subject, visitors should come away with a broad and clear description of the topic. The second site, called Orbit Diagrams (2 ) is provided by the Harvard-Smithsonian Center for Astrophysics. The diagrams are "intended to aid in the visualization of the three-dimensional nature of the orbits and how they are orientated with respect to the orbit of the earth." Next, from the University of Wisconsin-Madison Department of Astronomy comes the Moon Phases (3 ) interactive Web site. Users are able to animate the moon's orbit in various phases and views as well as learn all the names of the phases. The fourth site is another virtual visualization tool provided by NASA's Near Earth Object Program called Orbits (4 ). The site lets users enter the designation or name of any asteroid or comet and then view the three-dimensional orbit of that object. The next site, maintained by the Conservation, Astronomy, Physics and Soaring Page, is called Satellite Orbits - Gravitational Assist from Planets (5 ). The site contains information on Kepler's Laws, which apply to elliptical orbits involving two bodies, hyperbolic orbits, relative motion, and the gravitational sphere of influence. The sixth site is an educational lesson provided by Dr. Richard L. Bowman of Bridgewater College called Planetary Orbit Exercise (6 ). Students are given information on Keplar's Laws of Planetary Motion, a list of definitions, links to outside sites for additional information, and then several questions to answer. The Planetary Physical Data (7 ) page is part of the larger Smithsonian Center for Earth and Planetary Studies Web site. Visitors will find a list of planets along with various information such as their relative sidereal period of orbit, mean orbital velocity, orbital eccentricity, and much more. The last site related to orbits is an educational activity provided by the Physics Classroom called Circular Motion and Planetary Motion (8 ). Four lessons are presented including Motion Characteristics for Circular Motion, Applications of Circular Motion, Universal Gravitation, and Planetary and Satellite Motion. Each contain clear and well written descriptions along with all the necessary information for successful completion.

Brieske, Joel A.

23

Fermi-liquid computation of the phase diagram of high-Tc cuprate superconductors with an orbital antiferromagnetic pseudogap.  

PubMed

A 4-parameter Fermi-liquid calculation of the high-Tc cuprate phase diagram is reported. Simultaneously accounted for are the special doping densities of 5% and 16%, the d-wave functional form of the (orbital antiferromagnetic) pseudogap, the measured Tc, superconducting gap, pseudogap and superfluid density as a function of doping, the particle-hole doping asymmetry and the half-filling spin wave velocity. PMID:24483922

Laughlin, R B

2014-01-10

24

Exploring chemistry with the fragment molecular orbital method.  

PubMed

The fragment molecular orbital (FMO) method makes possible nearly linear scaling calculations of large molecular systems, such as water clusters, proteins and DNA. In particular, FMO has been widely used in biochemical applications involving protein-ligand binding and drug design. The method has been efficiently parallelized suitable for petascale computing. Many commonly used wave functions and solvent models have been interfaced with FMO. We review the historical background of FMO, and summarize its method development and applications. PMID:22410762

Fedorov, Dmitri G; Nagata, Takeshi; Kitaura, Kazuo

2012-06-01

25

Nonorthogonal molecular orbital method: Single-determinant theory  

NASA Astrophysics Data System (ADS)

Using the variational principle, we have derived a variant of the Adams-Gilbert equation for nonorthogonal orbitals of a single-determinant wave function, which we name the modified Adams-Gilbert equation. If we divide the molecular system into several subsystems, such as bonds, lone pairs, and residues, we can solve the equations for the subsystems one by one. Thus, this procedure has linear scaling. We have presented a practical procedure for solving the equations that is also applicable to macromolecular calculations. The numerical examples show that the procedure yields, with reasonable effort, results comparable with those of the Hartree-Fock-Roothaan method for orthogonal orbitals. To resolve the convergence difficulty in the self-consistent-field iterations, we have found that virtual molecular-orbital shifts are very effective.

Watanabe, Yoshihiro; Matsuoka, Osamu

2014-05-01

26

A Simple Demonstration of Atomic and Molecular Orbitals Using Circular Magnets  

ERIC Educational Resources Information Center

A quite simple and inexpensive technique is described here to represent the approximate shapes of atomic orbitals and the molecular orbitals formed by them following the principles of the linear combination of atomic orbitals (LCAO) method. Molecular orbitals of a few simple molecules can also be pictorially represented. Instructors can employ the…

Chakraborty, Maharudra; Mukhopadhyay, Subrata; Das, Ranendu Sekhar

2014-01-01

27

BetaVoid: molecular voids via beta-complexes and Voronoi diagrams.  

PubMed

Molecular external structure is important for molecular function, with voids on the surface and interior being one of the most important features. Hence, recognition of molecular voids and accurate computation of their geometrical properties, such as volume, area and topology, are crucial, yet most popular algorithms are based on the crude use of sampling points and thus are approximations even with a significant amount of computation. In this article, we propose an analytic approach to the problem using the Voronoi diagram of atoms and the beta-complex. The correctness and efficiency of the proposed algorithm is mathematically proved and experimentally verified. The benchmark test clearly shows the superiority of BetaVoid to two popular programs: VOIDOO and CASTp. The proposed algorithm is implemented in the BetaVoid program which is freely available at the Voronoi Diagram Research Center (http://voronoi.hanyang.ac.kr). PMID:24677176

Kim, Jae-Kwan; Cho, Youngsong; Laskowski, Roman A; Ryu, Seong Eon; Sugihara, Kokichi; Kim, Deok-Soo

2014-09-01

28

Origin of molecular conformational stability: Perspectives from molecular orbital interactions and density functional reactivity theory.  

PubMed

To have a quantitative understanding about the origin of conformation stability for molecular systems is still an unaccomplished task. Frontier orbital interactions from molecular orbital theory and energy partition schemes from density functional reactivity theory are the two approaches available in the literature that can be used for this purpose. In this work, we compare the performance of these approaches for a total of 48 simple molecules. We also conduct studies to flexibly bend bond angles for water, carbon dioxide, borane, and ammonia molecules to obtain energy profiles for these systems over a wide range of conformations. We find that results from molecular orbital interactions using frontier occupied orbitals such as the highest occupied molecular orbital and its neighbors are only qualitatively, at most semi-qualitatively, trustworthy. To obtain quantitative insights into relative stability of different conformations, the energy partition approach from density functional reactivity theory is much more reliable. We also find that the electrostatic interaction is the dominant descriptor for conformational stability, and steric and quantum effects are smaller in contribution but their contributions are indispensable. Stable molecular conformations prefer to have a strong electrostatic interaction, small molecular size, and large exchange-correlation effect. This work should shed new light towards establishing a general theoretical framework for molecular stability. PMID:25662636

Liu, Shubin; Schauer, Cynthia K

2015-02-01

29

A low Earth orbit molecular beam space simulation facility  

NASA Technical Reports Server (NTRS)

A brief synopsis of the low Earth orbit (LEO) satellite environment is presented including neutral and ionic species. Two ground based atomic and molecular beam instruments are described which are capable of simulating the interaction of spacecraft surfaces with the LEO environment and detecting the results of these interactions. The first detects mass spectrometrically low level fluxes of reactively and nonreactively surface scattered species as a function of scattering angle and velocity while the second ultrahigh velocity (UHV) molecular beam, laser induced fluorescence apparatus is capable of measuring chemiluminescence produced by either gas phase or gas-surface interactions. A number of proposed experiments are described.

Cross, J. B.

1984-01-01

30

The Interplay Between Graph Theory and Molecular Orbital Theory  

Microsoft Academic Search

\\u000a Molecular orbital (MO) theory, at various levels of approximation, is nowadays a standard tool of chemists.1,2 Similarly, chemical graph theory is also becoming a powerful device in the hands of chemists.3-5 A graph-theoretical analysis of the MO theory at the level of the Hückel approximation was carried out by a number of authors,\\u000a e.g.6-10 A pioneering work on the relationship

Nenad Trinajsti?; Zlatko Mihali?; Ante Graovac

31

On-orbit transport of molecular and particulate contaminants  

NASA Astrophysics Data System (ADS)

In an orbital environment, outgassed, offgassed, ambient, and vented molecular species can cause spacecraft performance degradation by direct impingement or by scattering with each other in the gas phase before and after reemitting from the spacecraft surfaces. This can cause detrimental conditions for the spacecraft surfaces and sensors who view through this cloud. Likewise particulates released by the spacecraft, or nearby systems, can deposit on surfaces, intercept optical lines-of-sight or recontact the vehicle later on in the mission, causing surface damage. This paper presents two models that have improved capability over previous similar models. The integrated spacecraft environments model (ISEM) can be used to predict the transport of spacecraft generated molecular species as they collisionally interact with each other and the ambient molecular environment. An ISEM analysis produces a three dimensional mapping of molecular density and velocity by molecular species, within a modeling volume defined by the user. This model is the next generation of the SPACE and Molflux contamination models and was developed through NASA funding. The orbital particulate trajectory model (OPT) can be used to predict the particulate locations of released particulates as a function of time relative to the spacecraft coordinate system as well as an Earth coordinate system. In this paper the capabilities, applications, validation, and availability of the (ISEM) and the (OPT) model are discussed.

Rantanen, Raymond; Gordon, Tim

1996-11-01

32

Polarized Molecular Orbital Model Chemistry. II. The PMO Method  

PubMed Central

We present a new semiempirical molecular orbital method based on neglect of diatomic differential overlap. This method differs from previous NDDO-based methods in that we include p orbitals on hydrogen atoms to provide a more realistic modeling of polarizability. As in AM1-D and PM3-D, we also include damped dispersion. The formalism is based on the original MNDO one, but in the process of parameterization we make some specific changes to some of the functional forms. The present article is a demonstration of the capability of the new approach, and it presents a successful parametrization for compounds composed only of hydrogen and oxygen atoms, including the important case of water clusters. PMID:23378824

Zhang, Peng; Fiedler, Luke; Leverentz, Hannah R.; Truhlar, Donald G.; Gao, Jiali

2012-01-01

33

Localization of molecular orbitals: from fragments to molecule.  

PubMed

Conspectus Localized molecular orbitals (LMO) not only serve as an important bridge between chemical intuition and molecular wave functions but also can be employed to reduce the computational cost of many-body methods for electron correlation and excitation. Therefore, how to localize the usually completely delocalized canonical molecular orbitals (CMO) into confined physical spaces has long been an important topic: It has a long history but still remains active to date. While the known LMOs can be classified into (exact) orthonormal and nonorthogonal, as well as (approximate) absolutely localized MOs, the ways for achieving these can be classified into two categories, a posteriori top-down and a priori bottom-up, depending on whether they invoke the global CMOs (or equivalently the molecular density matrix). While the top-down approaches have to face heavy tasks of minimizing or maximizing a given localization functional typically of many adjacent local extrema, the bottom-up ones have to invoke some tedious procedures for first generating a local basis composed of well-defined occupied and unoccupied subsets and then maintaining or resuming the locality when solving the Hartree-Fock/Kohn-Sham (HF/KS) optimization condition. It is shown here that the good of these kinds of approaches can be combined together to form a very efficient hybrid approach that can generate the desired LMOs for any kind of gapped molecules. Specifically, a top-down localization functional, applied to individual small subsystems only, is minimized to generate an orthonormal local basis composed of functions centered on the preset chemical fragments. The familiar notion for atomic cores, lone pairs, and chemical bonds emerges here automatically. Such a local basis is then employed in the global HF/KS calculation, after which a least action is taken toward the final orthonormal localized molecular orbitals (LMO), both occupied and virtual. This last step is very cheap, implying that, after the CMOs, the LMOs can be obtained essentially for free. Because molecular fragments are taken as the basic elements, the approach is in the spirit of "from fragments to molecule". Two representatives of highly conjugated molecules, that is, C12H2 and C60, are taken as showcases for demonstrating the success of the proposed approach. The use of the so-obtained LMOs will lead naturally to low-order scaling post-HF/KS methods for electron correlation or excitation. In addition, the underlying fragment picture allows for easy and pictorial interpretations of the correlation/excitation dynamics. PMID:25019464

Li, Zhendong; Li, Hongyang; Suo, Bingbing; Liu, Wenjian

2014-09-16

34

Control of substituent ligand over current through molecular devices: An ab initio molecular orbital theory  

Microsoft Academic Search

We explain the order of current curves of the ligand-substituent benzene-derivative devices by an ab initio molecular orbital theory on the basis of the first-principles density functional theory and the nonequilibrium Green function technique. The results of our calculation show the control of the substituent ligand over electronic transport through the molecular device. Contrary to the Hückel tight-binding result, we

H. Chen; J. Q. Lu; J. Wu; H. Mizuseki; Y. Kawazoe

2003-01-01

35

Phase diagram of 1D spin-orbit coupled Fermi gases in optical lattices  

NASA Astrophysics Data System (ADS)

We consider a one dimensional spin-orbit coupled Fermi gas in optical lattices with open boundary condition. This system belongs to the BDI symmetry class because the Hamiltonian can be made real when the Zeeman field is assumed to be along the z direction, thus the topological superfluid is characterized by Z, instead of Z2 class. In the optical lattice system, each site admits at most two fermions. The system can host plenty of phases depending on the filling factor and the Zeeman field. At finite Zeeman field we observe a strong competition between the topological superfluid phase and the Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) phase. The latter phase is more likely to be observed near the half filling. The spin-orbit coupling plays the role of enhancing the topological superfluid phase and suppressing the FFLO phase, which the Hartree shift plays an utterly opposite role. The possible observation of topological phase is also discussed in the presence of a harmonic trap.

Qu, Chunlei; Gong, Ming; Zhang, Chuanwei

2013-03-01

36

Sulfur at nickel-alumina interfaces - Molecular orbital theory  

NASA Technical Reports Server (NTRS)

Previous studies on Al-Ni alloys containing sulfur as an impurity suggest that, when S is in the interface between a metal and an oxide scale, it weakens the chemical bonding between them. This paper investigates factors responsible for this effect, using a molecular orbital theory to predict sulfur structures and electronic properties on the Ni-Al2O3 interface. It is shown that, in absence of S, the basal plane of Al2O3 will bind strongly through the Al(3+) cation surface to Ni (111). When segregated S impurity is present on the Ni surface, there are too few interfacial AlS bonds to effect good adhesion, leading to an inhibition of the oxide scale adhesion in NiCrAl alloys.

Hong, S. Y.; Anderson, Alfred B.; Smialek, James L.

1990-01-01

37

Monoclonal origin of localised orbital amyloidosis detected by molecular analysis.  

PubMed Central

AIMS: Primary localised orbital amyloidosis is a rare disease. The purpose of this study was to describe two cases of primary orbital amyloidosis and emphasise the value of molecular analysis of immunoglobulin gene rearrangement in identifying a monoclonal population of cells responsible for the amyloid production. METHODS: Charts and biopsy specimens of each case were reviewed. Conventional light microscopy, immunohistochemistry, and polymerase chain reaction (PCR) analysis for immunoglobulin gene rearrangement were performed in both cases. RESULTS: An unusual presentation of localised primary amyloidosis with bilateral and extensive enlargement of multiple extraocular muscles was seen in case 1. The presence of amyloid deposits was confirmed by biopsy in both cases. Evidence of a monoclonal population of plasma cells was shown by immunohistochemical analysis in case 2 only. The monoclonal origin of the cells responsible for the amyloid deposition was determined by PCR analysis demonstrating immunoglobulin heavy chain gene rearrangement in both cases. CONCLUSIONS: A monoclonal population of plasma cells responsible for the amyloid deposition was present in these two cases. PCR analysis is extremely helpful in determining monoclonality, a finding that may have important therapeutic and prognostic implications. Images PMID:8976732

Pasternak, S; White, V A; Gascoyne, R D; Perry, S R; Johnson, R L; Rootman, J

1996-01-01

38

THE FUELING DIAGRAM: LINKING GALAXY MOLECULAR-TO-ATOMIC GAS RATIOS TO INTERACTIONS AND ACCRETION  

SciTech Connect

To assess how external factors such as local interactions and fresh gas accretion influence the global interstellar medium of galaxies, we analyze the relationship between recent enhancements of central star formation and total molecular-to-atomic (H{sub 2}/H I) gas ratios, using a broad sample of field galaxies spanning early-to-late type morphologies, stellar masses of 10{sup 7.2}-10{sup 11.2} M{sub Sun }, and diverse stages of evolution. We find that galaxies occupy several loci in a ''fueling diagram'' that plots H{sub 2}/H I ratio versus mass-corrected blue-centeredness, a metric tracing the degree to which galaxies have bluer centers than the average galaxy at their stellar mass. Spiral galaxies of all stellar masses show a positive correlation between H{sub 2}/H I ratio and mass-corrected blue-centeredness. When combined with previous results linking mass-corrected blue-centeredness to external perturbations, this correlation suggests a systematic link between local galaxy interactions and molecular gas inflow/replenishment. Intriguingly, E/S0 galaxies show a more complex picture: some follow the same correlation, some are quenched, and a distinct population of blue-sequence E/S0 galaxies (with masses below key scales associated with transitions in gas richness) defines a separate loop in the fueling diagram. This population appears to be composed of low-mass merger remnants currently in late- or post-starburst states, in which the burst first consumes the H{sub 2} while the galaxy center keeps getting bluer, then exhausts the H{sub 2}, at which point the burst population reddens as it ages. Multiple lines of evidence suggest connected evolutionary sequences in the fueling diagram. In particular, tracking total gas-to-stellar mass ratios within the fueling diagram provides evidence of fresh gas accretion onto low-mass E/S0s emerging from their central starburst episodes. Drawing on a comprehensive literature search, we suggest that virtually all galaxies follow the same evolutionary patterns found in our broad sample.

Stark, David V.; Kannappan, Sheila J.; Eckert, Kathleen D. [Physics and Astronomy Department, University of North Carolina, Chapel Hill, NC 27516 (United States); Wei, Lisa H. [Atmospheric and Environmental Research, 131 Hartwell Avenue, Lexington, MA 02421 (United States); Baker, Andrew J. [Department of Physics and Astronomy, Rutgers, the State University of New Jersey, 136 Frelinghuysen Road, Piscataway, NJ 08854 (United States); Leroy, Adam K. [National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903 (United States); Vogel, Stuart N. [Department of Astronomy, University of Maryland, College Park, MD 20742 (United States)

2013-05-20

39

Band Formation in a Molecular Quantum Well via 2D Superatom Orbital Interactions  

SciTech Connect

By scanning tunneling microscopy and spectroscopy, we study nearly free electron band formation of the ?*lowest unoccupied molecular orbital of C?F? on a Cu(111) surface. In fractal islands, the lowest unoccupied molecular orbital energy systematically stabilizes with the number of interacting near-neighbor C?F? molecules. Density functional theory calculations reveal the origin of effective intermo- lecular orbital overlap in the previously unrecognized superatom character of the ?*orbital of ?F? molecules. The discovery of superatom orbitals in planar molecules offers a new universal principle for effective band formation, which can be exploited in designing organic semiconductors with nearly free electron properties

Dougherty, D. B.; Feng, Min; Petek, Hrvoje; Yates, John T.; Zhao, Jin

2012-12-28

40

Analyzing and Interpreting NMR Spin-Spin Coupling Constants Using Molecular Orbital Calculations  

ERIC Educational Resources Information Center

Molecular orbital plots are used to analyze and interpret NMR spin-spin coupling constants, also known as J coupling constants. Students have accepted the concept of contributions to molecular properties from individual orbitals without the requirement to provide explicit equations.

Autschbach, Jochen; Le Guennic, Boris

2007-01-01

41

Efficient Molecular Dynamics Simulations of Multiple Radical Center Systems Based on the Fragment Molecular Orbital Method  

SciTech Connect

The fully analytic energy gradient has been developed and implemented for the restricted open-shell Hartree–Fock (ROHF) method based on the fragment molecular orbital (FMO) theory for systems that have multiple open-shell molecules. The accuracy of the analytic ROHF energy gradient is compared with the corresponding numerical gradient, illustrating the accuracy of the analytic gradient. The ROHF analytic gradient is used to perform molecular dynamics simulations of an unusual open-shell system, liquid oxygen, and mixtures of oxygen and nitrogen. These molecular dynamics simulations provide some insight about how triplet oxygen molecules interact with each other. Timings reveal that the method can calculate the energy gradient for a system containing 4000 atoms in only 6 h. Therefore, it is concluded that the FMO-ROHF method will be useful for investigating systems with multiple open shells.

Nakata, Hiroya [Tokyo Institute of Technology; Schmidt, Michael W [Ames Laboratory; Fedorov, Dmitri G [National Institute of Advanced Industrial Science and Technology (AIST); Kitaura, Kazuo [Kobe University; Nakamura, Shinichiro [Nakamura Lab; Gordon, Mark S [Ames Laboratory

2014-10-16

42

Quantifying the relative molecular orbital alignment for molecular junctions with similar chemical linkage to electrodes  

NASA Astrophysics Data System (ADS)

Estimating the relative alignment between the frontier molecular orbitals (MOs) that dominates the charge transport through single-molecule junctions represents a challenge for theory. This requires approaches beyond the widely employed framework provided by the density functional theory, wherein the Kohn–Sham ‘orbitals’ are treated as if they were real MOs, which is not the case. In this paper, we report results obtained by means of quantum chemical calculations, including the equation-of-motion coupled-cluster singles and doubles, which is the state-of-the-art of quantum chemistry for medium-size molecules like those considered here. These theoretical results are validated against data on the MO energy offset relative to the electrodes’ Fermi energy extracted from experiments for junctions based on 4,4’-bipyridine and 1,4-dicyanobenzene.

Bâldea, Ioan

2014-11-01

43

Molecular structures of carotenoids as predicted by MNDO-AM1 molecular orbital calculations  

NASA Astrophysics Data System (ADS)

Semi-empirical molecular orbital calculations using AM1 Hamiltonian (MNDO-AM1 method) were performed for a number of biologically important carotenoid molecules, namely all- trans-?-carotene, all- trans-zeaxanthin, and all- trans-violaxanthin (found in higher plants and algae) together with all- trans-canthaxanthin, all- trans-astaxanthin, and all- trans-tunaxanthin in order to predict their stable structures. The molecular structures of all- trans-?-carotene, all- trans-canthaxanthin, and all- trans-astaxanthin predicted based on molecular orbital calculations were compared with those determined by X-ray crystallography. Predicted bond lengths, bond angles, and dihedral angles showed an excellent agreement with those determined experimentally, a fact that validated the present theoretical calculations. Comparison of the bond lengths, bond angles and dihedral angles of the most stable conformer among all the carotenoid molecules showed that the displacements are localized around the substituent groups and hence around the cyclohexene rings. The most stable conformers of all- trans-zeaxanthin and all- trans-violaxanthin gave rise to a torsion angle around the C6-C7 bond to be ±48.7 and -84.8°, respectively. This difference is a key factor in relation to the biological function of these two carotenoids in plants and algae (the xanthophyll cycle). Further analyses by calculating the atomic charges and using enpartment calculations (division of bond energies between component atoms) were performed to ascribe the cause of the different observed torsion angles.

Hashimoto, Hideki; Yoda, Takeshi; Kobayashi, Takayoshi; Young, Andrew J.

2002-02-01

44

Moving Beyond the Single Center--Ways to Reinforce Molecular Orbital Theory in an Inorganic Course  

ERIC Educational Resources Information Center

It is suggested that molecular theory should be taught earlier in the inorganic chemistry curriculum even in the introductory chemistry course in order to integrate molecular orbital arguments more effectively throughout the curriculum. The method of teaching relies on having access to molecular modeling software as having access to such software…

Cass, Marion E.; Hollingsworth, William E.

2004-01-01

45

Construction of Ligand Group Orbitals for Polyatomics and Transition-Metal Complexes Using an Intuitive Symmetry-Based Approach  

ERIC Educational Resources Information Center

A molecular orbital (MO) diagram, especially its frontier orbitals, explains the bonding and reactivity for a chemical compound. It is therefore important for students to learn how to construct one. The traditional methods used to derive these diagrams rely on linear algebra techniques to combine ligand orbitals into symmetry-adapted linear…

Johnson, Adam R.

2013-01-01

46

Bounds and phase diagram of efficiency at maximum power for tight-coupling molecular motors  

E-print Network

The efficiency at maximum power (EMP) for tight-coupling molecular motors is investigated based on the constitutive relation between the flux and thermodynamic force. It is found that the EMP is equal to 1/2 when the flux $J$ and thermodynamic force $F$ satisfy $J=J^\\prime F$ where $J^\\prime$ represents the derivative with respect to $F$, and that the EMP is smaller (larger) than 1/2 when $JJ^\\prime F$). The lower and upper bounds of EMP are proved to be $[1-\\mathcal{W}(\\mathrm{e}^{1-\\Delta\\mu})]/\\Delta\\mu$ and $[\\mathcal{W}(\\mathrm{e}^{1+\\Delta\\mu})-1]/\\Delta\\mu$, respectively, where $\\mathcal{W}(.)$ represents the Lambert's W function while $\\Delta \\mu$ is called the reduced chemical potential which is the ratio of the released free energy of fuel in each motor step to the energy scale of thermal motion at the physiological temperature. A phase diagram with phase boundary $\\delta= 2/{\\Delta\\mu}-1/(\\mathrm{e}^{\\Delta\\mu/2}-1)$ is constructed, which shows how $\\Delta \\mu$ and the load distribution factor $\\de...

Tu, Z C

2012-01-01

47

Mechanism of hydrogen activation by frustrated Lewis pairs: A molecular orbital approach  

NASA Astrophysics Data System (ADS)

A detailed molecular orbital treatment of the heterolytic hydrogen splitting by bulky Lewis acid-base pairs is presented. The frontier molecular orbitals of the proposed reactive intermediate are shown to be preorganized but otherwise practically identical to those of the free acid and base molecules. The concerted interaction of the Lewis centers with hydrogen leading to the polarization and, ultimately, to the cleavage of the H=H bond is examined, and the bridge role of hydrogen molecule in the electron transfer is pointed out. The formation of the new covalent bonds is monitored by bond order and natural localized molecular orbital calculations, and found to be synchronous. The stability of the product is interpreted on the basis of favorable orbital interactions. A comparison of various hydrogen activation mechanisms emphasizes the common donation/back-donation motifs and the different ways of making them feasible.

Hamza, Andrea; Stirling, András; András Rokob, Tibor; Pápai, Imre

48

Electron transport through heterocyclic molecule: ab initio molecular orbital theory  

Microsoft Academic Search

We have calculated the electron transport properties of molecule wires by an ab initio molecule orbital theory on the basis of the first-principles density functional theory (DFT) and the non-equilibrium Green function (NEGF) technique. The wires are made of heterocyclic molecule (furan, thiophene, and pyrrole, shown in first figure), in contact with the atomic scale Au electrodes. The results of

W. W. Cheng; Y. X. Liao; H. Chen; H. Mizuseki; Y. Kawazoe

2004-01-01

49

Molecular orbital model of optical centers in bismuth-doped glasses.  

PubMed

Spectroscopic properties of optical fibers with a bismuth-doped silicate glass core are explained on the basis of molecular orbital theory and a solution of the Schrödinger equation, which takes into account the exchange, the spin-orbital, and the glass field potential interactions of s, p, and d electron shells of bismuth with s(sigma), p(sigma), and p(pi) orbits of oxygen atoms. The approach can explain the IR luminescence properties of other optical centers formed by other atoms with the same structure of electron shells as the bismuth atom. The model of transitions based on intramolecular charge transfer between molecular orbital and metallic states is proposed. PMID:19448817

Kustov, E F; Bulatov, L I; Dvoyrin, V V; Mashinsky, V M

2009-05-15

50

Solution of multi-center molecular integrals of Slater-type orbitals  

NASA Technical Reports Server (NTRS)

The troublesome multi-center molecular integrals of Slater-type orbitals (STO) in molecular physics calculations can be evaluated by using the Fourier transform and proper coupling of the two center exchange integrals. A numerical integration procedure is then readily rendered to the final expression in which the integrand consists of well known special functions of arguments containing the geometrical arrangement of the nuclear centers and the exponents of the atomic orbitals. A practical procedure was devised for the calculation of a general multi-center molecular integrals coupling arbitrary Slater-type orbitals. Symmetry relations and asymptotic conditions are discussed. Explicit expressions of three-center one-electron nuclear-attraction integrals and four-center two-electron repulsion integrals for STO of principal quantum number n=2 are listed. A few numerical results are given for the purpose of comparison.

Tai, H.

1989-01-01

51

Density functional theory, molecular dynamics, and differential scanning calorimetry study of the RbF-CsF phase diagram  

NASA Astrophysics Data System (ADS)

A multiscale modeling approach is developed to compute the phase diagram of the RbF-CsF binary system. The mixing enthalpies of the (Rb,Cs)F solid and liquid solutions are evaluated using density functional theory and classical molecular dynamics calculations, respectively. For the solid solution, 18 different configurations are studied with density functional theory and the surrounded atom model is applied in order to compute the configurational partition function. We also measure the solidus and liquidus equilibria using differential scanning calorimetry. Finally the RbF-CsF phase diagram is constructed using the calculated excess free enthalpies of the solid and liquid solutions and a very good agreement with our experimental data is found.

Beneš, O.; Zeller, Ph.; Salanne, M.; Konings, R. J. M.

2009-04-01

52

Detection of Molecular Hydrogen Orbiting a ``Naked'' T Tauri Star  

NASA Astrophysics Data System (ADS)

Astronomers have established that for a few million years, newborn stars possess disks of orbiting gas and dust. Such disks, which are likely sites of planet formation, appear to disappear once these stars reach ages of (5-10)×106 yr; yet, >=107 yr is thought necessary for giant planet formation. If disks dissipate in less time than is needed for giant planet formation, such planets may be rare and those known around nearby stars would be anomalies. Here we report the discovery of H2 gas orbiting a weak-lined T Tauri star heretofore presumed nearly devoid of circumstellar material. We estimate that a significant amount of H2 persists in the gas phase, but only a tiny fraction of this mass emits in the near-infrared. We propose that this star possesses an evolved disk that has escaped detection thus far because much of the dust has coagulated into planetesimals. This discovery suggests that the theory that disks are largely absent around such stars should be reconsidered. The widespread presence of such disks would indicate that planetesimals can form quickly and giant planet formation can proceed to completion before the gas in circumstellar disks disperses.

Bary, Jeffrey S.; Weintraub, David A.; Kastner, Joel H.

2002-09-01

53

Molecular systems biology: data-flow diagram modeling of process in protein  

Microsoft Academic Search

In this paper, we introduce a new method of modeling tool for a biological process - central dogma. The data-flow diagram is used as a representation of the whole data input and output, which enables us to simulate, analyze, and manipulate (in the future) at our disposal. From DNA to protein via RNA is the one of most well-known biological

J. W. Yeol; I. Barjis; Y. S. Ryu

2005-01-01

54

High resolution NEXAFS of perylene and PTCDI: a surface science approach to molecular orbital analysis.  

PubMed

We made use of synchrotron radiation to perform near edge X-ray absorption fine structure spectroscopy, NEXAFS, at the carbon K-edge of perylene and perylene-tetracarboxylic-diimide, PTCDI. Reference spectra measured for isolated molecules in the gas phase are compared with polarization dependent NEXAFS spectra measured on highly oriented thin films in order to study the symmetry of the molecular orbitals. The molecular overlayers are grown onto the rutile TiO2(110) surface for which the large anisotropic corrugation effectively drives the molecular orientation, while its dielectric nature prevents the rehybridization of the molecular orbitals. We employed density functional theory, DFT, calculations to disentangle the contribution of specific carbon atoms to the molecular density of states. Numerical simulations correctly predict the observed NEXAFS azimuthal dichroism of the ?* resonances above the ionization threshold, from which we determine the full geometric orientation of the overlayer molecules. A discrepancy observed for the spectral contribution of the imide carbon atom to the calculated unoccupied molecular orbitals has been explained in terms of initial state effects, as determined by Hartree-Fock corrections and in full agreement with the corresponding shift of the C 1s core level measured by X-ray photoelectron spectroscopy, XPS. PMID:24924641

Fratesi, Guido; Lanzilotto, Valeria; Stranges, Stefano; Alagia, Michele; Brivio, Gian Paolo; Floreano, Luca

2014-07-28

55

Thermochemistry of Aluminum Species for Combustion Modeling from Ab Initio Molecular Orbital Calculations  

E-print Network

Thermochemistry of Aluminum Species for Combustion Modeling from Ab Initio Molecular Orbital initio methods for computational thermochemistry have been applied to aluminum compounds expected to be present during combustion of aluminum particles. The computed enthalpies of formation at 298.15 K agree

Swihart, Mark T.

56

A molecular orbital study of bond length and angle variations in framework structures  

Microsoft Academic Search

Molecular orbital calculations on a variety of silicate and aluminosilicate molecules have been used to explore the bonding forces that govern tetrahedral bond length variations, r(TO), in framework silicates and aluminosilicates. Not only do the calculations provide insight into the variety of structural types and the substitution limits of one tetrahedral atom for another, but they also provide an understanding

K. L. Geisinger; G. V. Gibbs; A. Navrotsky

1985-01-01

57

Synthesis, Structure, and Molecular Orbital Calculations of (Pyrazolato)vanadium(III) Complexes Understanding 2  

E-print Network

FULL PAPER Synthesis, Structure, and Molecular Orbital Calculations of (Pyrazolato)vanadium,[a] Mary Jane Heeg,[a] H. Bernhard Schlegel,[a] and Charles H. Winter*[a] Keywords: Vanadium / Pyrazolato ligands / Ab initio calculations / N ligands / Coordination modes Treatment of trichlorotris(tetrahydrofuran)vanadium

Schlegel, H. Bernhard

58

Molecular Orbital Studies of Titanium Nitride Chemical Vapor Deposition: Gas Phase Complex Formation,  

E-print Network

Molecular Orbital Studies of Titanium Nitride Chemical Vapor Deposition: Gas Phase Complex Received June 6, 2000 The chemical vapor deposition (CVD) of titanium nitride can be carried out with TiCl4 Titanium nitride thin films have a variety of proper- ties, such as extreme hardness, high chemical

Schlegel, H. Bernhard

59

Hydrogen Spectra, Molecular Association and Orbital Radii in the Solar System  

Microsoft Academic Search

A relationship between the average orbital radii of the planets and their satellites in the solar system and the spectra of atomic and molecular hydrogen is identified and investigated. In this model, stimulated radiative association resonances develop early on in the disk of the protosun that cause the disk to cool at only certain radii, with each radius depending on

James C. Lombardi Sr.

2003-01-01

60

The Nonlocalized Molecular Orbital Model to Analyze Infrared and Vibrational Circular Dichroism Spectra: a Database Approach  

Microsoft Academic Search

The nonlocalized molecular orbital model (NMO) of Nafie and Freedman is implemented at the ab initio level to calculate IR and VCD intensities based on contributions of fixed partial charges (FPC), charge flow along bonds (CF) and atomic polarizations (PP). It is theoretically demonstrated that NMO is equivalent to the ab initio RHF formalism for IR intensities. Using local symmetry

Felix Maurer

1993-01-01

61

Molecular Orbital Studies of Zinc Oxide Chemical Vapor Deposition: Gas-Phase Hydrolysis of Diethyl Zinc,  

E-print Network

region.1,2 Doping with indium, gallium, or aluminum improves these properties.3-5 These characteristicsMolecular Orbital Studies of Zinc Oxide Chemical Vapor Deposition: Gas-Phase Hydrolysis of Diethyl deposition of zinc oxide thin films can be carried out with diethyl zinc and water vapor. The present study

Schlegel, H. Bernhard

62

Pyrite oxidation and reduction - Molecular orbital theory considerations. [for geochemical redox processes  

NASA Technical Reports Server (NTRS)

In this paper, molecular orbital theory is used to explain a heterogeneous reaction mechanism for both pyrite oxidation and reduction. The mechanism demonstrates that the oxidation of FeS2 by Fe(3+) may occur as a result of three important criteria: (1) the presence of a suitable oxidant having a vacant orbital (in case of liquid phase) or site (solid phase) to bind to the FeS2 via sulfur; (2) the initial formation of a persulfido (disulfide) bridge between FeS2 and the oxidant, and (3) an electron transfer from a pi(asterisk) orbital in S2(2-) to a pi or pi(asterisk) orbital of the oxidant.

Luther, George W., III

1987-01-01

63

The Two Electron Molecular Bond Revisited: From Bohr Orbits to Two-Center Orbitals  

Microsoft Academic Search

In this review we first discuss extension of Bohr's 1913 molecular model and\\u000ashow that it corresponds to the large-D limit of a dimensional scaling\\u000a(D-scaling) analysis, as developed by Herschbach and coworkers.\\u000a In a separate but synergetic approach to the two-electron problem, we\\u000asummarize recent advances in constructing analytical models for describing the\\u000atwo-electron bond. The emphasis here is

Goong Chen; Siu A. Chin; Yusheng Dou; Kishore T. Kapale; Moochan Kim; Anatoly A. Svidzinsky; Kerim Urtekin; Han Xiong; Marlan O. Scully

2005-01-01

64

Measurement of Thermopower and Current-Voltage Characteristics of Molecular Junctions to Identify Orbital Alignment  

SciTech Connect

We report an experimental technique that concurrently measures the Seebeck coefficient and the current-voltage (I-V) characteristics of a molecular junction to determine the identity and the effective energetic separation of the molecular orbital closest to the electrodes’ Fermi level. Junctions created by contacting a gold-coated atomic force microscope tip with a monolayer of molecules assembled on a gold substrate were found to have a Seebeck coefficient of (+16.9±1.4) ?V/K. This positive value unambiguously shows that the highest occupied molecular orbital (HOMO) dominates charge transport. Further, by analyzing the (I-V) characteristics, the HOMO level is estimated to be ? 0.69?eV with respect to the Fermi level.

Tan, Aaron; Sadat, Seid; Reddy, Pramod

2010-01-01

65

Finite-temperature orbital-free DFT molecular dynamics: Coupling PROFESS and QUANTUM ESPRESSO  

NASA Astrophysics Data System (ADS)

Implementation of orbital-free free-energy functionals in the PROFESS code and the coupling of PROFESS with the QUANTUM ESPRESSO code are described. The combination enables orbital-free DFT to drive ab initio molecular dynamics simulations on the same footing (algorithms, thermostats, convergence parameters, etc.) as for Kohn-Sham (KS) DFT. All the non-interacting free-energy functionals implemented are single-point: the local density approximation (LDA; also known as finite-T Thomas-Fermi, ftTF), the second-order gradient approximation (SGA or finite-T gradient-corrected TF), and our recently introduced finite-T generalized gradient approximations (ftGGA). Elimination of the KS orbital bottleneck via orbital-free methodology enables high-T simulations on ordinary computers, whereas those simulations would be costly or even prohibitively time-consuming for KS molecular dynamics (MD) on very high-performance computer systems. Example MD simulations on H over a temperature range 2000 K?T?4,000,000 K are reported, with timings on small clusters (16-128 cores) and even laptops. With respect to KS-driven calculations, the orbital-free calculations are between a few times through a few hundreds of times faster.

Karasiev, Valentin V.; Sjostrom, Travis; Trickey, S. B.

2014-12-01

66

Orbital redistribution in molecular nanostructures mediated by metal-organic bonds.  

PubMed

Dicyanovinyl-quinquethiophene (DCV5T-Me2) is a prototype conjugated oligomer for highly efficient organic solar cells. This class of oligothiophenes are built up by an electron-rich donor (D) backbone and terminal electron-deficient acceptor (A) moieties. Here, we investigated its structural and electronic properties when it is adsorbed on a Au(111) surface using low temperature scanning tunneling microscopy/spectroscopy (STM/STS) and atomic force microscopy (AFM). We find that DCV5T-Me2 self-assembles in extended chains, stabilized by intercalated Au atoms. The effect of metal-ligand hybridization with Au adatoms causes an energetic downshift of the DCV5T-Me2 lowest unoccupied molecular orbital (LUMO) with respect to the uncoordinated molecules on the surface. The asymmetric coordination of a gold atom to only one molecular end group leads to an asymmetric localization of the LUMO and LUMO+1 states at opposite sides. Using model density functional theory (DFT) calculations, we explain such orbital reshaping as a consequence of linear combinations of the original LUMO and LUMO+1 orbitals, mixed by the attachment of a bridging Au adatom. Our study shows that the alignment of molecular orbitals and their distribution within individual molecules can be modified by contacting them to metal atoms in specific sites. PMID:25244124

Yang, Zechao; Corso, Martina; Robles, Roberto; Lotze, Christian; Fitzner, Roland; Mena-Osteritz, Elena; Bäuerle, Peter; Franke, Katharina J; Pascual, Jose I

2014-10-28

67

Molecular-orbital description of doubly excited atomic states generalized to arbitrary dimension  

NASA Astrophysics Data System (ADS)

The molecular-orbital description of two-electron atoms [J. M. Feagin and J. S. Briggs, Phys. Rev. A 37, 4599 (1988)], derived from H+2 by interchanging the roles of electrons and nuclei, is generalized to D dimensions. For H+2 itself there exist myriad exact interdimensional degeneracies because D-->D+2 is equivalent to m-->m+1, augmenting by unity the projection of the electronic angular momentum on the internuclear axis. When the molecular orbitals (MO's) are transcribed to treat two-electron motion, additional constraints limit the exact degeneracies to states in D=3 and 5, but many approximate degeneracies persist. Since the MO description emphasizes rotational properties of the two-electron atom, the link between dimension and orbital angular momentum is a pervasive feature. We use this link to classify groups of quasidegenerate doubly excited atomic energies and to explain striking similarities among certain pairs of hyperspherical or molecular-orbital two-electron potential curves.

Rost, J. M.; Sung, S. M.; Herschbach, D. R.; Briggs, J. S.

1992-09-01

68

The dynamical evolution of molecular clouds near the Galactic Centre - I. Orbital structure and evolutionary timeline  

NASA Astrophysics Data System (ADS)

We recently proposed that the star-forming potential of dense molecular clouds in the Central Molecular Zone (CMZ, i.e. the central few 100 pc) of the Milky Way is intimately linked to their orbital dynamics, potentially giving rise to an absolute-time sequence of star-forming clouds. In this paper, we present an orbital model for the gas stream(s) observed in the CMZ. The model is obtained by integrating orbits in the empirically constrained gravitational potential and represents a good fit (? _red^2=2.0) to the observed position-velocity distribution of dense (n > several 103 cm-3) gas, reproducing all of its key properties. The orbit is also consistent with observational constraints not included in the fitting process, such as the 3D space velocities of Sgr B2 and the Arches and Quintuplet clusters. It differs from previous, parametric models in several respects: (1) the orbit is open rather than closed due to the extended mass distribution in the CMZ, (2) its orbital velocity (100-200 km s-1) is twice as high as in previous models, and (3) Sgr A* coincides with the focus of the (eccentric) orbit rather than being offset. Our orbital solution supports the recently proposed scenario in which the dust ridge between G0.253+0.016 (`the Brick') and Sgr B2 represents an absolute-time sequence of star-forming clouds, of which the condensation was triggered by the tidal compression during their most recent pericentre passage. We position the clouds on a common timeline and find that their pericentre passages occurred 0.30-0.74 Myr ago. Given their short free-fall times (tff ˜ 0.34 Myr), the quiescent cloud G0.253+0.016 and the vigorously star-forming complex Sgr B2 are separated by a single free-fall time of evolution, implying that star formation proceeds rapidly once collapse has been initiated. We provide the complete orbital solution, as well as several quantitative predictions of our model (e.g. proper motions and the positions of star formation `hotspots'). The paper is concluded with a discussion of the assumptions and possible caveats, as well as the position of the model in the Galactic context, highlighting its relation to large-scale gas accretion, the dynamics of the bar, the x2 orbital family, and the origin of the Arches and Quintuplet clusters.

Kruijssen, J. M. Diederik; Dale, James E.; Longmore, Steven N.

2015-02-01

69

Analysis of charge transfer effects in molecular complexes based on absolutely localized molecular orbitals  

E-print Network

Analysis of charge transfer effects in molecular complexes based on absolutely localized molecular to measure the degree of intermolecular electron density delocalization charge transfer in molecular complexes. ALMO charge transfer analysis CTA enables separation of the forward and backward charge transfer

Bell, Alexis T.

70

Molecular orbital tomography for adsorbed molecules: is a correct description of the final state really unimportant?  

NASA Astrophysics Data System (ADS)

The application of the ‘orbital tomography’ technique to obtain direct images of molecular orbitals of adsorbed molecules from angle-resolved photoemission data, first proposed by Puschnig et al (2009 Science 326 702), is an extremely attractive idea, but is based on the assumption that the photoemission can be described by a plane wave final state. It is well known that this neglect of the spherical-wave nature of the initial emission and of the role of final state scattering both within the molecule and from the substrate can lead to serious errors. Despite this, in the albeit simple systems studied so far the method appears to work reasonably well. Here we provide a detailed critique of this problem, highlight situations in which the orbital tomography approach is likely to lead to major errors, and propose test experiments that could provide clear information on the extent of these problems.

Bradshaw, A. M.; Woodruff, D. P.

2015-01-01

71

Metastable isomorphous phase diagram of the peritectic Ni-Ru system predicted by ab initio and molecular dynamics calculations  

NASA Astrophysics Data System (ADS)

With the aid of ab initio calculation, an n -body potential of the equilibrium peritectic Ni-Ru (fcc-hcp) system is derived under the second-moment approximation of the tight-binding formalism. The derived Ni-Ru potential is proven to be relevant not only in reproducing some static properties, such as the cohesive energies and elastic constants, etc., also in reproducing some dynamic properties, such as the melting points and thermal-expansion coefficients, etc. Applying the proven realistic Ni-Ru potential, molecular dynamics simulations show that a crystalline solid solution of either fcc or hcp structure would always win while competing with its amorphous counterpart over the entire composition range, predicting that under a nonequilibrium condition, the Ni-Ru system may feature an isomorphous phase diagram, i.e., predicting a hardly glass-forming ability of the Ni-Ru system, which, however, was previously defined as a possibly glass-forming system. Interestingly, the prediction is in good agreement with the fact that no amorphous Ni-Ru alloy has so far been obtained by any glass-producing technique as well as with that deduced from the thermodynamic calculations. Besides, the present calculations demonstrate the possibility for an equilibrium fcc-hcp system to have a metastable isomorphous phase diagram, implying that a part of the previously defined possibly glass-forming systems may convert into the hardly glass-forming ones.

Li, J. H.; Guo, H. B.; Kong, L. T.; Liu, B. X.

2005-01-01

72

On-orbit free molecular flow aerodynamic characteristics of a proposal space operations center configuration  

NASA Technical Reports Server (NTRS)

A proposed configuration for a Space Operations Center is presented in its eight stages of buildup. The on orbit aerodynamic force and moment characteristics were calculated for each stage based upon free molecular flow theory. Calculation of the aerodynamic characteristics was accomplished through the use of an orbital aerodynamic computer program, and the computation method is described with respect to the free molecular theory used. The aerodynamic characteristics are presented in tabulated form for each buildup stage at angles of attack from 0 to 360 degrees and roll angles from -60 to +60 degrees. The reference altitude is 490 kilometers, however, the data should be applicable for altitudes below 490 kilometers down to approximately 185 kilometers.

Romere, P. O.

1982-01-01

73

Communication through molecular bridges: Different bridge orbital trends result in common property trends.  

PubMed

Common trends in communication through molecular bridges are ubiquitous in chemistry, such as the frequently observed exponential decay of conductance/electron transport and of exchange spin coupling with increasing bridge length, or the increased communication through a bridge upon closing a diarylethene photoswitch. For antiferromagnetically coupled diradicals in which two equivalent spin centers are connected by a closed-shell bridge, the molecular orbitals (MOs) whose energy splitting dominates the coupling strength are similar in shape to the MOs of the dithiolated bridges, which in turn can be used to rationalize conductance. Therefore, it appears reasonable to expect the observed common property trends to result from common orbital trends. We illustrate based on a set of model compounds that this assumption is not true, and that common property trends result from either different pairs of orbitals being involved, or from orbital energies not being the dominant contribution to property trends. For substituent effects, an effective modification of the ? system can make a comparison difficult. © 2014 Wiley Periodicals, Inc. PMID:25382464

Proppe, Jonny; Herrmann, Carmen

2015-02-01

74

Molecular orbital view of the electronic coupling between two metal nanoparticles  

NASA Astrophysics Data System (ADS)

The electronic coupling between metal nanoparticles is responsible for intriguing new phenomena observed when the particles are near touching contact, which is exemplified by recent investigations of nanoparticle dimers. However, little is known about the role of the molecular orbitals of the nanoparticle dimers. The expectation is that the physics and chemistry of the system must be reflected in the orbitals that control the bonding at touching contact. This expectation is borne out in the present investigation in which we present a comprehensive theoretical study based on density-functional theory of the electronic coupling between two silver nanoparticles. We explain our findings by studying the molecular orbitals of the dimers as a function of the separation and relative orientation between the nanoparticles. We show that as the nanoparticles approach each other a bond-forming step takes place, and that the strength of the hybridization is a key element to determine various properties of the system. We find that the relative orientation between the nanoparticles plays an important role in determining the strength of the coupling which can be visualized by the spatial distribution of the highest occupied molecular orbitals. Moreover, the strength of the coupling will in turn determine the ease of their transition to the nonlinear dielectric-response regime. This effect allows for the tunability of the electronic coupling and magnetic moment of the dimer. Our findings are essential for understanding and tailoring desired physical and chemical properties of closely aggregated nanoparticles relevant for applications such as surface-enhanced Raman scattering and quantum transport in molecular devices.

Troparevsky, M. Claudia; Zhao, Ke; Xiao, Di; Eguiluz, Adolfo G.; Zhang, Zhenyu

2010-07-01

75

Cluster molecular orbital description of the electronic structures of mixed-valence iron oxides and silicates  

USGS Publications Warehouse

A molecular orbital description, based on spin-unrestricted X??-scattered wave calculations, is given for the electronic structures of mixed valence iron oxides and silicates. The cluster calculations show that electron hopping and optical intervalence charge-transger result from weak FeFe bonding across shared edges of FeO6 coordination polyhedra. In agreement with Zener's double exchange model, FeFe bonding is found to stabilize ferromagnetic coupling between Fe2+ and Fe3+ cations. ?? 1986.

Sherman, D.M.

1986-01-01

76

Hydrogen Spectra, Molecular Association and Orbital Radii in the Solar System  

Microsoft Academic Search

A relationship between the average orbital radii of the planets and their\\u000asatellites in the solar system and the spectra of atomic and molecular hydrogen\\u000ais identified and investigated. In this model, stimulated radiative association\\u000aresonances develop early on in the disk of the protosun that cause the disk to\\u000acool at only certain radii, with each radius depending on

James C. Lombardi Sr.

2003-01-01

77

Density Functional Molecular Orbital Calculations on Longer DNA–DNA and PNA–DNA Double Strands  

Microsoft Academic Search

Summary. Stable structures and electronic properties of hybridized DNA–DNA and PNA–DNA double strands with common base sequences were theoretically investigated by molecular orbital calculations based on the density functional theory. The computed hybridization energy in PNA–DNA is greater than that in the DNA– DNA double strand. The origin of the larger stability of PNA–DNA double strand is ascribed to the

Takayuki Natsume; Yasuyuki Ishikawa; Kenichi Dedachi; Noriyuki Kurita

78

Spin-orbital entangled molecular jeff states in lacunar spinel compounds  

NASA Astrophysics Data System (ADS)

The entanglement of the spin and orbital degrees of freedom through the spin-orbit coupling has been actively studied in condensed matter physics. In several iridium oxide systems, the spin-orbital entangled state, identified by the effective angular momentum jeff, can host novel quantum phases. Here we show that a series of lacunar spinel compounds, GaM4X8 (M=Nb, Mo, Ta and W and X=S, Se and Te), gives rise to a molecular jeff state as a new spin-orbital composite on which the low-energy effective Hamiltonian is based. A wide range of electron correlations is accessible by tuning the bandwidth under external and/or chemical pressure, enabling us to investigate the cooperation between spin-orbit coupling and electron correlations. As illustrative examples, a two-dimensional topological insulating phase and an anisotropic spin Hamiltonian are investigated in the weak and strong coupling regimes, respectively. Our finding can provide an ideal platform for exploring jeff physics and the resulting emergent phenomena.

Kim, Heung-Sik; Im, Jino; Han, Myung Joon; Jin, Hosub

2014-06-01

79

Accurate description of phase diagram of clathrate hydrates at the molecular level.  

PubMed

In order to accurately estimate the thermodynamic properties of hydrogen clathrate hydrates, we developed a method based on the solid solution theory of van der Waals and Platteeuw. This model allows one to take into account the influence of guest molecules on the host lattice and guest-guest interactions--especially when more than one guest molecule occupies a cage. The free energies, equations of state, and chemical potentials of hydrogen and mixed propane-hydrogen clathrate hydrates of cubic structure II with different cage fillings have been estimated using this approach. Moreover, the proposed theory has been used for construction p-T phase diagrams of hydrogen hydrate and mixed hydrogen-propane hydrates in a wide range of pressures and temperatures. For the systems with well defined interactions the calculated curves of "guest gas-hydrate-ice I(h)" equilibrium agree with the available experimental data. We also believe that the present model allows one not only to calculate the hydrogen storage ability of known hydrogen hydrate but also predict this value for structures that have not yet been realized by experiment. PMID:20059082

Belosudov, Rodion V; Subbotin, Oleg S; Mizuseki, Hiroshi; Kawazoe, Yoshiyuki; Belosludov, Vladimir R

2009-12-28

80

Molecular Orbital Study of the First Excited State of the OLED Material Tris(8-hydroxyquinoline)aluminum(III)  

E-print Network

Molecular Orbital Study of the First Excited State of the OLED Material Tris(8-hydroxyquinoline)aluminum, Michigan 48202 Received February 6, 2001. Revised Manuscript Received May 16, 2001 Tris(8-hydroxyquinoline)aluminum

Schlegel, H. Bernhard

81

Constructing Periodic Phase Space Orbits from ab Initio Molecular Dynamics Trajectories to Analyze Vibrational Spectra: Case Study of  

E-print Network

Constructing Periodic Phase Space Orbits from ab Initio Molecular Dynamics Trajectories to Analyze States *S Supporting Information ABSTRACT: A method of analysis is introduced to probe the spectral comprising operations that invoke the time-domain symmetries (or periodic phase space orbits) reflected

Iyengar, Srinivasan S.

82

A polarizable force-field model for quantum-mechanical-molecular-mechanical Hamiltonian using expansion of point charges into orbitals  

Microsoft Academic Search

We present an ab initio polarizable representation of classical molecular mechanics (MM) atoms by employing an angular momentum-based expansion scheme of the point charges into partial wave orbitals. The charge density represented by these orbitals can be fully polarized, and for hybrid quantum-mechanical-molecular-mechanical (QM\\/MM) calculations, mutual polarization within the QM\\/MM Hamiltonian can be obtained. We present the mathematical formulation and

P. K. Biswas; Valentin Gogonea

2008-01-01

83

Initial elementary processes in tetrafluoroethylene plasma: An ab initio molecular orbital study  

NASA Astrophysics Data System (ADS)

Initial elementary processes in tetrafluoroethylene plasma are studied by using an ab initio molecular orbital method. The energy-surfaces at excited states are obtained by the Hartree-Fock method with a double zeta basis set, plus Rydberg orbitals. A ?-?* transition is low-lying both at singlet and triplet excited states. Vinyl-polymerization-type reactions are expected in the presence of some radical species via these transitions. The C=C bond cleaves via a triplet ?-?* transition to form CF2. The predicted elementary processes via these states are compatible with experimental results that C2F4* and CF2 are primary precursors. No excited states that bring about a C—F bond cleavage are obtained within 10 eV of the ground state. As a path for a C—F bond cleavage, a dissociative electron attachment process is found in a low energy region. This process is considered to be important for producing fluorine anions.

Sato, Kota; Komatsu, Toru; Iwabuchi, Susumu

1993-12-01

84

DETECTION OF A MOLECULAR DISK ORBITING THE NEARBY, 'OLD', CLASSICAL T TAURI STAR MP MUSCAE  

SciTech Connect

We have used the Atacama Pathfinder Experiment 12 m telescope to detect circumstellar CO emission from MP Muscae (MP Mus; K1 IVe), a nearby (D {approx} 100 pc), actively accreting, {approx}7 Myr old pre-main-sequence (pre-MS) star. The CO emission line profile measured for MP Mus is indicative of an orbiting disk with radius {approx}120 AU, assuming that the central star mass is 1.2 M {sub sun} and the disk inclination is i {approx} 30{sup 0}. The inferred disk molecular gas mass is {approx}3 M {sub +}. MP Mus thereby joins TW Hya and V4046 Sgr as the only late-type (low-mass), pre-MS star systems within {approx}100 pc of Earth that are known to retain orbiting, molecular disks. We also report the nondetection (with the Institut de Radio Astronomie Millimetrique 30 m telescope) of CO emission from another 10 nearby (D {approx_lt} 100 pc), dusty, young (age {approx}10-100 Myr) field stars of spectral type A-G. We discuss the implications of these results for the timescales for stellar and Jovian planet accretion from, and dissipation of, molecular disks around young stars.

Kastner, Joel H.; Sacco, G. G. [Center for Imaging Science, Rochester Institute of Technology, 54 Lomb Memorial Drive, Rochester, NY 14623 (United States); Hily-Blant, Pierry; Forveille, Thierry [Laboratoire d'Astrophysique de Grenoble, Universite Joseph Fourier-CNRS, BP 53, 38041 Grenoble Cedex (France); Zuckerman, B., E-mail: jhk@cis.rit.ed [Department of Physics and Astronomy, University of California, Los Angeles 90095, CA (United States)

2010-11-10

85

Envelope molecular-orbital theory of extended systems. I. Electronic states of organic quasilinear nanoheterostructures  

NASA Astrophysics Data System (ADS)

A conceptually appealing and computationally economical course-grained molecular-orbital (MO) theory for extended quasilinear molecular heterostructures is presented. The formalism, which is based on a straightforward adaptation, by including explicitly the vacuum, of the envelope-function approximation widely employed in solid-state physics leads to a mapping of the three-dimensional single-particle eigenvalue equations into simple one-dimensional hole and electron Schrödinger-like equations with piecewise-constant effective potentials and masses. The eigenfunctions of these equations are envelope MO's in which the short-wavelength oscillations present in the full MO's, associated with the atomistic details of the molecular potential, are smoothed out automatically. The approach is illustrated by calculating the envelope MO's of high-lying occupied and low-lying virtual ? states in prototypical nanometric heterostructures constituted by oligomers of polyacetylene and polydiacetylene. Comparison with atomistic electronic-structure calculations reveals that the envelope-MO energies agree very well with the energies of the ? MO's and that the envelope MO's describe precisely the long-wavelength variations of the ? MO's. This envelope MO theory, which is generalizable to extended systems of any dimensionality, is seen to provide a useful tool for the qualitative interpretation and quantitative prediction of the single-particle quantum states in mesoscopic molecular structures and the design of nanometric molecular devices with tailored energy levels and wavefunctions.

Arce, J. C.; Perdomo-Ortiz, A.; Zambrano, M. L.; Mujica-Martínez, C.

2011-03-01

86

Ab Initio Molecular Orbital Study on Acceleration Mechanism of Silane Plasma Chemical Vapor Deposition by Diborane  

NASA Astrophysics Data System (ADS)

An acceleration mechanism of silane plasma chemical vapor deposition by diborane is proposed on the basis of an ab initio molecular orbital calculation. Hydrogen abstraction from the growing surface by BH2 is calculated to be much more favorable than that by SiH3 from both the kinetic and thermodynamic viewpoint. Thus, the abstraction by BH2 is predicted to occur frequently, although the concentration of BH2 is considerably lower than that of SiH3. This process creates a dangling bond on the growing surface and then the deposition rate is increased.

Sato, Kota; Kubota, Yasuyo

2011-05-01

87

Incorporation of solvation effects into the fragment molecular orbital calculations with the Poisson-Boltzmann equation  

NASA Astrophysics Data System (ADS)

We developed FMO-PB method, which incorporates solvation effects into the Fragment Molecular Orbital calculation with the Poisson-Boltzmann equation. This method retains good accuracy in energy calculations with reduced computational time. We calculated the solvation free energies for polyalanines, Alpha-1 peptide, tryptophan cage, and complex of estrogen receptor and 17 ?-estradiol to show the applicability of this method for practical systems. From the calculated results, it has been confirmed that the FMO-PB method is useful for large biomolecules in solution. We also discussed the electric charges which are used in solving the Poisson-Boltzmann equation.

Watanabe, Hirofumi; Okiyama, Yoshio; Nakano, Tatsuya; Tanaka, Shigenori

2010-11-01

88

Counterpoise-corrected interaction energy analysis based on the fragment molecular orbital scheme  

NASA Astrophysics Data System (ADS)

Basis set superposition error (BSSE) correction with counterpoise (CP) procedure under the environmental electrostatic potential is newly introduced to interfragment interaction energy (IFIE), which is important for interaction analysis in the fragment molecular orbital method. The CP correction for IFIE is applied to a stacked dimer of base pair and a protein-ligand complex of estrogen receptor and 17?-estradiol with scaled third-order Møller-Plesset perturbation theory. The BSSEs amount to about quarter of IFIE for hydrogen-bonding and electrostatic interactions and half or even more for dispersion interactions. Estimation of IFIE with the CP correction is therefore preferred for the quantitative discussion.

Okiyama, Yoshio; Fukuzawa, Kaori; Yamada, Haruka; Mochizuki, Yuji; Nakano, Tatsuya; Tanaka, Shigenori

2011-06-01

89

An electron momentum spectroscopy study of the highest occupied molecular orbital of difluoromethane  

NASA Astrophysics Data System (ADS)

The highest occupied molecular orbital (HOMO)of difluoromethane (CH 2F 2) has been firstly studied by binary (e, 2e) electron momentum spectroscopy (EMS), at the impact energy of 1200 eV plus binding energy, and using symmetric non-coplanar kinematics. The experimental momentum profile of the HOMO is compared with Hartree-Fock (HF)and density functional theory (DFT) methods with various basis sets. The experimental measurement is well described by the HF and DFT calculations except for the low-momentum region.

Su, G. L.; Ning, C. G.; Zhang, S. F.; Ren, X. G.; Zhou, H.; Li, B.; Huang, F.; Li, G. Q.; Deng, J. K.; Wang, Y.

2004-05-01

90

A combined effective fragment potential-fragment molecular orbital method. I. The energy expression and initial applications  

Microsoft Academic Search

The effective fragment potential (EFP) method, a model potential for treating solvent effects and other intermolecular interactions, is interfaced with an electronic structure method, the fragment molecular orbital (FMO) method, that is able to retain high accuracy for ab initio calculations on large molecular systems. The accuracy of the total energies in this novel combined FMO\\/EFP method is assessed by

Takeshi Nagata; Dmitri G. Fedorov; Kazuo Kitaura; Mark S. Gordon

2009-01-01

91

A combined effective fragment potential–fragment molecular orbital method. I. The energy expression and initial applications  

Microsoft Academic Search

The effective fragment potential (EFP) method, a model potential for treating solvent effects and other intermolecular interactions, is interfaced with an electronic structure method, the fragment molecular orbital (FMO) method, that is able to retain high accuracy for ab initio calculations on large molecular systems. The accuracy of the total energies in this novel combined FMO\\/EFP method is assessed by

Takeshi Nagata; Dmitri G. Fedorov; Kazuo Kitaura; Mark S. Gordon

2009-01-01

92

Introductory Molecular Orbital Theory: An Honors General Chemistry Computational Lab as Implemented Using Three-Dimensional Modeling Software  

ERIC Educational Resources Information Center

In this study, a computational molecular orbital theory experiment was implemented in a first-semester honors general chemistry course. Students used the GAMESS (General Atomic and Molecular Electronic Structure System) quantum mechanical software (as implemented in ChemBio3D) to optimize the geometry for various small molecules. Extended Huckel…

Ruddick, Kristie R.; Parrill, Abby L.; Petersen, Richard L.

2012-01-01

93

Molecular dynamics of single-particle impacts predicts phase diagrams for large scale pattern formation.  

PubMed

Energetic particle irradiation can cause surface ultra-smoothening, self-organized nanoscale pattern formation or degradation of the structural integrity of nuclear reactor components. A fundamental understanding of the mechanisms governing the selection among these outcomes has been elusive. Here we predict the mechanism governing the transition from pattern formation to flatness using only parameter-free molecular dynamics simulations of single-ion impacts as input into a multiscale analysis, obtaining good agreement with experiment. Our results overturn the paradigm attributing these phenomena to the removal of target atoms via sputter erosion: the mechanism dominating both stability and instability is the impact-induced redistribution of target atoms that are not sputtered away, with erosive effects being essentially irrelevant. We discuss the potential implications for the formation of a mysterious nanoscale topography, leading to surface degradation, of tungsten plasma-facing fusion reactor walls. Consideration of impact-induced redistribution processes may lead to a new design criterion for stability under irradiation. PMID:21505432

Norris, Scott A; Samela, Juha; Bukonte, Laura; Backman, Marie; Djurabekova, Flyura; Nordlund, Kai; Madi, Charbel S; Brenner, Michael P; Aziz, Michael J

2011-01-01

94

Unrestricted Hartree-Fock based on the fragment molecular orbital method: energy and its analytic gradient.  

PubMed

A consideration of the surrounding environment is necessary for a meaningful analysis of the reaction activity in large molecular systems. We propose an approach to perform unrestricted Hartree-Fock (UHF) calculations within the framework of the fragment molecular orbital (FMO) method (FMO-UHF) to study large systems with unpaired electrons. Prior to an energy analysis one has to optimize geometry, which requires an accurate analytic energy gradient. We derive the FMO-UHF energy and its analytic gradient and implement them into GAMESS. The performance of FMO-UHF is evaluated for a solvated organic molecule and a solvated metal complex, as well as for the active part of a protein, in terms of energy, gradient, and geometry optimization. PMID:22852600

Nakata, Hiroya; Fedorov, Dmitri G; Nagata, Takeshi; Yokojima, Satoshi; Ogata, Koji; Kitaura, Kazuo; Nakamura, Shinichiro

2012-07-28

95

Molecular orbital predictions of the vibrational frequencies of some molecular ions  

NASA Technical Reports Server (NTRS)

The initial detections of IR vibration-rotation bands in polyatomic molecular ions by recent spectroscopic advances were guided by ab initio prediction of vibrational frequencies. The present calculations predict the vibrational frequencies of additional ions which are candidates for laboratory analysis. Neutral molecule vibrational frequencies were computed at three levels of theory and then compared with experimental data; the effect of scaling was also investigated, in order to determine how accurately vibrational frequencies could be predicted. For 92 percent of the frequencies examined, the relatively simple HF/6-31G theory's vibrational frequencies were within 100/cm of experimental values, with a mean absolute error of 49/cm. On this basis, the frequencies of 30 molecular ions (many possessing astrophysical significance) were computed.

Defrees, D. J.; Mclean, A. D.

1985-01-01

96

INVESTIGATION OF THE CORRELATION BETWEEN THE ENERGY OF THE HIGHESTOCCUPIED MOLECULAR ORBITAL (HOMO) AND THE LOGARITHM OF THE OH RATECONSTANT OF HYDROFLUOROCARBONS AND HYDROFLUOROETHERS  

EPA Science Inventory

A regression based model was developed to determine whether highest occupied molecular orbital (HOMO) energies, calculated using Kohn-Sham orbital density functional theory (DFT) could be used to estimate the OH rate constants of hydrofluorocarbons (HFCS) and hydrofluoroethers (H...

97

Dissociative electron attachment in nonplanar chlorocarbons with pi*/sigma*-coupled molecular orbitals.  

PubMed

Total absolute cross sections for the dissociative electron attachment (DEA) process are reported for a series of nonplanar ethylenic and phenylic compounds monosubstituted with (CH(2))(n)Cl groups, where n=1-4. Coupling between the local pi* molecular orbitals provided by the unsaturated moieties and the sigma* (C-Cl) orbital is thus examined as a function of the separation of these groups. In particular, the coupling is viewed from the perspective of the interacting temporary negative ions formed by short lived occupation of these orbitals and their decay into the DEA channel. A theoretical treatment of "remote" bond breaking, presented elsewhere, satisfactorily accounts for DEA in the chloroethylenic compounds presented here and emphasizes not only the delocalization of the coupled anionic wave functions but the importance of their relative phases. The dependence of the cross sections on the vertical attachment energies, measured by electron transmission spectroscopy, is also explored and compared to that found previously in chlorinated alkanes. PMID:20210397

Aflatooni, K; Gallup, G A; Burrow, P D

2010-03-01

98

Radio Emission Line Surveys of the Molecular Disks Orbiting TW Hya and V4046 Sgr  

NASA Astrophysics Data System (ADS)

We have conducted the first comprehensive mm-wave molecular emission line surveys of the evolved circumstellar disks orbiting the nearby pre-main sequence stars TW Hya (D = 54 pc) and V4046 Sgr AB (D = 73 pc). Both systems have relatively advanced ages of roughly 10 Myr; nevertheless, these disks are known to retain significant residual gaseous components, as evidenced by previous radio and infrared detections of molecular and atomic emission lines and optical/X-ray spectral signatures of ongoing stellar accretion. Our unbiased broad-band radio spectral surveys were performed with the Atacama Pathfinder Experiment (APEX) 12 meter telescope and are intended to yield a complete census of bright molecular emission lines in the 0.85-1.0 mm wavelength range. Here, we present initial results, with particular emphasis on newly detected molecular species and emission lines that are potential diagnostics of the effects of high-energy radiation from pre-main sequence stars on disk gas chemistry and physical conditions. This research is supported by National Science Foundation grant AST-1108950 to RIT.

Kastner, Joel H.; Hily-Blant, P.; Rodriguez, D.; Punzi, K.; Forveille, T.

2013-01-01

99

Equation of state of dense plasmas: Orbital-free molecular dynamics as the limit of quantum molecular dynamics for high-Z elements  

SciTech Connect

The applicability of quantum molecular dynamics to the calculation of the equation of state of a dense plasma is limited at high temperature by computational cost. Orbital-free molecular dynamics, based on a semiclassical approximation and possibly on a gradient correction, is a simulation method available at high temperature. For a high-Z element such as lutetium, we examine how orbital-free molecular dynamics applied to the equation of state of a dense plasma can be regarded as the limit of quantum molecular dynamics at high temperature. For the normal mass density and twice the normal mass density, we show that the pressures calculated with the quantum approach converge monotonically towards those calculated with the orbital-free approach; we observe a faster convergence when the orbital-free approach includes the gradient correction. We propose a method to obtain an equation of state reproducing quantum molecular dynamics results up to high temperatures where this approach cannot be directly implemented. With the results already obtained for low-Z plasmas, the present study opens the way for reproducing the quantum molecular dynamics pressure for all elements up to high temperatures.

Danel, J.-F.; Blottiau, P.; Kazandjian, L.; Piron, R.; Torrent, M. [CEA, DAM, DIF, 91297 Arpajon (France)

2014-10-15

100

Equation of state of dense plasmas: Orbital-free molecular dynamics as the limit of quantum molecular dynamics for high-Z elements  

NASA Astrophysics Data System (ADS)

The applicability of quantum molecular dynamics to the calculation of the equation of state of a dense plasma is limited at high temperature by computational cost. Orbital-free molecular dynamics, based on a semiclassical approximation and possibly on a gradient correction, is a simulation method available at high temperature. For a high-Z element such as lutetium, we examine how orbital-free molecular dynamics applied to the equation of state of a dense plasma can be regarded as the limit of quantum molecular dynamics at high temperature. For the normal mass density and twice the normal mass density, we show that the pressures calculated with the quantum approach converge monotonically towards those calculated with the orbital-free approach; we observe a faster convergence when the orbital-free approach includes the gradient correction. We propose a method to obtain an equation of state reproducing quantum molecular dynamics results up to high temperatures where this approach cannot be directly implemented. With the results already obtained for low-Z plasmas, the present study opens the way for reproducing the quantum molecular dynamics pressure for all elements up to high temperatures.

Danel, J.-F.; Blottiau, P.; Kazandjian, L.; Piron, R.; Torrent, M.

2014-10-01

101

Molecular geometry, conformational, vibrational spectroscopic, molecular orbital and Mulliken charge analysis of 2-acetoxybenzoic acid  

NASA Astrophysics Data System (ADS)

The Fourier transform infrared (FT-IR) and FT-Raman spectra of 2-acetoxybenzoic acid (2ABA), a painkiller agent were recorded in the region 4000-450 cm-1 and 5000-50 cm-1 respectively. Hartree Fock (HF) and Density functional theory (DFT) methods have been used to determine its optimized geometrical parameter, atomic charges, and vibrational wavenumbers and intensity of the vibrational bands of the title molecule. The computed vibrational wave numbers were compared with the FT-IR and FT-Raman experimental data. The computational calculations were done at HF and DFT/B3LYP level with 6-311++G(d,p) basis set. The complete vibrational assignments were performed on the basis of the potential energy distribution (PED) analysis. The Mulliken charges, UV-Visible spectral analysis and HOMO-LUMO energy gap have been calculated and reported. The B3LYP method of calculated parameters is a good complement with the experimental findings. The thermodynamic properties like entropy, heat capacity and zero vibrational energy have been calculated and discussed. The electrostatic potential (ESP) contour surface and molecular electrostatic potential (MESP) of the molecule were constructed.

Govindasamy, P.; Gunasekaran, S.; Srinivasan, S.

2014-09-01

102

IMAGING THE MOLECULAR DISK ORBITING THE TWIN YOUNG SUNS OF V4046 Sgr  

SciTech Connect

We have imaged the disk surrounding the nearby (D {approx} 73 pc), {approx}12 Myr, classical T Tauri binary system V4046 Sgr with the Submillimeter Array (SMA) at an angular resolution of {approx}2''. We detect a rotating disk in {sup 12}CO(2-1) and {sup 13}CO(2-1) emission and resolve the continuum emission at 1.3 mm. We infer disk gas and dust masses of {approx}110 and {approx}40 Earth masses, respectively. Fits to a power-law disk model indicate that the molecular disk extends to {approx}370 AU and is viewed at an inclination of between {approx}33{sup 0} and {approx}39{sup 0} for dynamical stellar masses ranging from 1.8 M {sub sun} down to 1.5 M {sub sun} (the range of the total mass previously determined for the central, 2.4 day spectroscopic binary). This range of disk inclination is consistent with that assumed in deducing the central binary mass (i.e., 35{sup 0}), suggesting that the V4046 Sgr binary system and its circumbinary, molecular disk are coplanar. In light of the system's age and binarity, the presence of an extensive molecular disk orbiting V4046 Sgr provides constraints on the timescales of processes related to Jovian planet formation and demonstrates that circumbinary Jovian planets potentially could form around close binary systems.

Rodriguez, David R. [Department of Physics and Astronomy, University of California, Los Angeles, CA 90095 (United States); Kastner, Joel H. [Center for Imaging Science, Rochester Institute of Technology, 54 Lomb Memorial Drive, Rochester, NY 14623 (United States); Wilner, David; Qi, Chunhua, E-mail: drodrigu@astro.ucla.ed, E-mail: jhk@cis.rit.ed, E-mail: dwilner@cfa.harvard.ed, E-mail: cqi@cfa.harvard.ed [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Mail Stop 42, Cambridge, MA 02138 (United States)

2010-09-10

103

Fourier transform photoelectron diffraction and its application to molecular orbitals and surface structure  

SciTech Connect

Photoemission intensities from the molecular orbitals of c(2x2)CO/Pt(111) over a wide photon energy range were measured and analyzed by the same methods developed for structural studies using core levels. The 4{sigma} orbital center of gravity is found to be concentrated between the C and O atoms, while that of the 5{sigma} orbital lies between the C atom and the Pt surface. The C 1s photoelectron diffraction was used to determine the adsorption geometry. The earlier ambiguity that multiple scattering is needed to correctly model a {chi} curve while single scattering is sufficient for understanding major peaks in the ARPEFS-FTS is clarified by studying the clean Ni(111) surface. In the normal emission case, several different combinations of scattering events have similar path length differences (PLDs), and can either cancel each other or enhance the corresponding FT peak. In the off-normal case the degeneracy is greatly reduced due to the lower degree of symmetry. In normal emission AR PEFS, up to third order multiple scattering is needed to describe fully both the {chi} curve and its FT spectrum. To improve the spectral resolution in the ARPEFS-FT analysis, several new spectral analysis methods are introduced. With both autocorrelation autoregression (ACAR) and autocorrelation eigenvector (ACE), we can produce a reliable power spectrum by following the order-closing procedure. The best spectra are usually obtained when the autocorrelation sequence is computed with lags up to half the data range. A simple way of determining surface adsorption sites is proposed as follows: First use a single scattering cluster for possible adsorption sites to construct the geometrical PLDs from the strong backscattering events; then compare these PLDs with those obtained from the ARPEFS-FT analysis of the experimental data. After the preferred adsorption site is determined, fine tune the interlayer distances according to the positional R-factor.

Zhou, Xin

1998-11-30

104

New methods for accelerating the convergence of molecular electronic integrals over exponential type orbitals  

NASA Astrophysics Data System (ADS)

This review on molecular integrals for large electronic systems (MILES) places the problem of analytical integration over exponential-type orbitals (ETOs) in a historical context. After reference to the pioneering work, particularly by Barnett, Shavitt and Yoshimine, it focuses on recent progress towards rapid and accurate analytic solutions of MILES over ETOs. Software such as the hydrogenlike wavefunction package Alchemy by Yoshimine and collaborators is described. The review focuses on convergence acceleration of these highly oscillatory integrals and in particular it highlights suitable nonlinear transformations. Work by Levin and Sidi is described and applied to MILES. A step by step description of progress in the use of nonlinear transformation methods to obtain efficient codes is provided. The recent approach developed by Safouhi is also presented. The current state of the art in this field is summarized to show that ab initio analytical work over ETOs is now a viable option.

Safouhi, Hassan; Hoggan, Philip

2003-01-01

105

Oxygen evolution on a SrFeO3 anode - Mechanistic considerations from molecular orbital theory  

NASA Technical Reports Server (NTRS)

Various pathways proposed in the literature for the evolution of O2 in electrochemical oxidations are explored using the atom superposition and electron delocalization molecular orbital (ASED-MO) theory and the cluster models of the SrFeO3 surface as a prototype material. Calculations indicate that oxygen atoms can be easily formed on the (100) surface as well as on the edge cation sites of a SrFeO3 anode by the discharge of OH(-), followed by its deprotonation and electron transfer to the electrode. The O atoms can form O2 on the edge and corner sites, where the Fe(4+) is coordinated to four and three bulk oxygen anions, respectively. The calculations strongly disfavor mechanisms involving coupling of oxygen atoms adsorbed on different cations as well as a mechanism featuring an ozone intermediate.

Mehandru, S. P.; Anderson, Alfred B.

1989-01-01

106

Satellite structure in the 2psigma molecular orbital transitions in slow heavy ion collisions  

SciTech Connect

The binding energy of the 2psigma molecular orbital formed transiently in a slow heavy ion collision shows a flat minimum at a large internuclear distance. Electronic transitions in this minimum provide a satellite structure in the 2psigma X-ray continuum, which was not found in the original search. New measurements show that the satellite is only evident at very small collision velocities, since the collision broadening is much larger for asymmetric collision systems than the theory predicts. The present theory of collision broadening takes into account only the linear term of the change in transition energy dE/dR which may not be appropriate in cases where the second term d/sup 2/E/dR/sup 2/ is likely to be dominant.

Stockli, P.

1983-04-01

107

Molecular orbital studies in oxidation: Sulfate formation and metal-metal oxide adhesion  

NASA Technical Reports Server (NTRS)

The chemical mechanisms for sulfate formation from sodium chloride and sulfur trioxide, which is a product of jet fuel combustion was determined. Molten sodium sulfate leads to hot corrosion of the protective oxide layers on turbine blades. How yttrium dopants in nidkel-aluminum alloys used in turbine blades reduce the spalling rate of protective alumina films and enhance their adhesion was also determined. Two other fulfate mechanisms were deduced and structure of carbon monoxide on a clean chronium and clean platinum-titanium alloys surfaces was determined. All studies were by use of the atom superposition and electron delocalization molecular orbital (ASED-MO) theory. Seven studies were completed. Their titles and abstracts are given.

Anderson, A. B.

1985-01-01

108

Hybrid RHF/MP2 Geometry Optimizations with the Effective Fragment Molecular Orbital Method  

PubMed Central

The frozen domain effective fragment molecular orbital method is extended to allow for the treatment of a single fragment at the MP2 level of theory. The approach is applied to the conversion of chorismate to prephenate by Chorismate Mutase, where the substrate is treated at the MP2 level of theory while the rest of the system is treated at the RHF level. MP2 geometry optimization is found to lower the barrier by up to 3.5 kcal/mol compared to RHF optimzations and ONIOM energy refinement and leads to a smoother convergence with respect to the basis set for the reaction profile. For double zeta basis sets the increase in CPU time relative to RHF is roughly a factor of two. PMID:24558430

Christensen, Anders S.; Steinmann, Casper; Fedorov, Dmitri G.; Jensen, Jan H.

2014-01-01

109

Mapping Enzymatic Catalysis Using the Effective Fragment Molecular Orbital Method: Towards all ab initio Biochemistry  

PubMed Central

We extend the Effective Fragment Molecular Orbital (EFMO) method to the frozen domain approach where only the geometry of an active part is optimized, while the many-body polarization effects are considered for the whole system. The new approach efficiently mapped out the entire reaction path of chorismate mutase in less than four days using 80 cores on 20 nodes, where the whole system containing 2398 atoms is treated in the ab initio fashion without using any force fields. The reaction path is constructed automatically with the only assumption of defining the reaction coordinate a priori. We determine the reaction barrier of chorismate mutase to be kcal mol?1 for MP2/cc-pVDZ and for MP2/cc-pVTZ in an ONIOM approach using EFMO-RHF/6-31G(d) for the high and low layers, respectively. PMID:23593259

Steinmann, Casper; Fedorov, Dmitri G.; Jensen, Jan H.

2013-01-01

110

Crystallographic and molecular-orbital studies on the geometry of antifolate drugs.  

PubMed Central

In the common dihydrofolate reductase inhibitors an amino substituent replaces the pteridine carbonyl oxygen atom of folates, with altered hydrogen-bonding properties and size. Flexibility in the amino groups could facilitate enzyme binding. Studies of cycloguanil hydrochloride by neutron diffraction show both in-plane and out-of-plane deformation of amino groups. Molecular-orbital calculations ab initio on 2,4-diamino-5-methylpyrimidinium cation confirm that the 4-amino group is readily deformable. The 2,4-diaminoquinazoline structure is reported. Atomic co-ordinates, thermal parameters, bond distances and bond angles for cycloguanil and 2,4-diaminoquinazoline have been deposited as Supplementary Publication SUP 50108 (13 pages) at the British Library Lending Division, Boston Spa. Wetherby, West Yorkshire LS23, 7BQ, U.K., from whom copies can be obtained on the terms indicated in Biochem. J. (1978) 169, 5. PMID:6893149

Hunt, W E; Schwalbe, C H; Bird, K; Mallinson, P D

1980-01-01

111

A mass spectrometric and ab initio molecular orbital characterization of thionitrosyl hydride (H-N=S)  

NASA Astrophysics Data System (ADS)

A combination of tandem mass spectrometry experiments (collisional activation and neutralization-reionization mass spectrometry) and ab initio molecular orbital calculations was used to provide evidence for the stability of thionitrosyl hydride, H-N=S, and to characterize it. Experimentally, HNS has been generated using three different precursors. The (HNS) potential energy surface has been explored in the lowest-lying singlet, triplet and doublet ionized states using (PU)MP4/6-311++G(2df,2pd) energies based on (U)MP2/6-31G(d,p) geometries. Predictions for several spectroscopic properties of NHS have been made on the basis of MO calculations and empirical corrections. These include geometry, rotational constants, vibrational wavenumbers, dipole moment, 14N nuclear quadrupole coupling constant, triplet-singlet energy gap, electron and proton affinities, ionization and ?* ? n transition energies.

Nguyen, Minh Tho; Vanquickenborne, L. G.; Plisnier, Michel; Flammang, Robert

112

Fragment molecular orbital calculations on red fluorescent protein (DsRed)  

NASA Astrophysics Data System (ADS)

We have performed the calculations of configuration interaction singles with perturbative doubles correction (CIS(D)) in conjunction with the multilayer fragment molecular orbital (MLFMO) scheme for a red fluorescent protein isolated from Discosoma coral (known as DsRed). The pigment geometry of DsRed was first examined by employing several model molecules whose spectra in gas-phase were actually observed, and an adequacy was confirmed. The excitation energy was then calculated to be 2.28 eV at the MLFMO-CIS(D)/6-31G ? level. The emission energy was also estimated to be 2.21 eV similarly. These theoretical values were in good agreement with the corresponding experimental values of 2.22 eV and 2.13 eV.

Mochizuki, Yuji; Nakano, Tatsuya; Amari, Shinji; Ishikawa, Takeshi; Tanaka, Kiyoshi; Sakurai, Minoru; Tanaka, Shigenori

2007-01-01

113

Design principle for increasing charge mobility of ?-conjugated polymers using regularly localized molecular orbitals  

PubMed Central

The feasibility of using ?-conjugated polymers as next-generation electronic materials is extensively studied; however, their charge mobilities are lower than those of inorganic materials. Here we demonstrate a new design principle for increasing the intramolecular charge mobility of ?-conjugated polymers by covering the ?-conjugated chain with macrocycles and regularly localizing ?-molecular orbitals to realize an ideal orbital alignment for charge hopping. Based on theoretical predictions, insulated wires containing meta-junctioned poly(phenylene–ethynylene) as the backbone units were designed and synthesized. The zigzag wires exhibited higher intramolecular charge mobility than the corresponding linear wires. When the length of the linear region of the zigzag wires was increased to 10 phenylene–ethynylene units, the intramolecular charge mobility increased to 8.5?cm2?V?1?s?1. Theoretical analysis confirmed that this design principle is suitable for obtaining ideal charge mobilities in ?-conjugated polymer chains and that it provides the most effective pathways for inter-site hopping processes. PMID:23575695

Terao, Jun; Wadahama, Akihisa; Matono, Akitoshi; Tada, Tomofumi; Watanabe, Satoshi; Seki, Shu; Fujihara, Tetsuaki; Tsuji, Yasushi

2013-01-01

114

Kohn-Sham orbitals and potentials from quantum Monte Carlo molecular densities  

SciTech Connect

In this work we show the possibility to extract Kohn-Sham orbitals, orbital energies, and exchange correlation potentials from accurate Quantum Monte Carlo (QMC) densities for atoms (He, Be, Ne) and molecules (H{sub 2}, Be{sub 2}, H{sub 2}O, and C{sub 2}H{sub 4}). The Variational Monte Carlo (VMC) densities based on accurate Jastrow Antisymmetrised Geminal Power wave functions are calculated through different estimators. Using these reference densities, we extract the Kohn-Sham quantities with the method developed by Zhao, Morrison, and Parr (ZMP) [Phys. Rev. A 50, 2138 (1994)]. We compare these extracted quantities with those obtained form CISD densities and with other data reported in the literature, finding a good agreement between VMC and other high-level quantum chemistry methods. Our results demonstrate the applicability of the ZMP procedure to QMC molecular densities, that can be used for the testing and development of improved functionals and for the implementation of embedding schemes based on QMC and Density Functional Theory.

Varsano, Daniele, E-mail: daniele.varsano@nano.cnr.it [Dipartimento di Fisica, Sapienza-Università di Roma, P.le Aldo Moro 5, 00185 Roma (Italy)] [Dipartimento di Fisica, Sapienza-Università di Roma, P.le Aldo Moro 5, 00185 Roma (Italy); Barborini, Matteo [Dipartimento di ingegneria e scienze dell'informazione e matematica, Università degli studi dell'Aquila, Via Vetoio, Coppito, 67100 L'Aquila (Italy) [Dipartimento di ingegneria e scienze dell'informazione e matematica, Università degli studi dell'Aquila, Via Vetoio, Coppito, 67100 L'Aquila (Italy); Dipartimento di Scienze Fisiche e Chimiche, Università degli studi dell'Aquila, Via Vetoio, Coppito, 67100 L'Aquila (Italy); Guidoni, Leonardo, E-mail: leonardo.guidoni@univaq.it [Dipartimento di Scienze Fisiche e Chimiche, Università degli studi dell'Aquila, Via Vetoio, Coppito, 67100 L'Aquila (Italy)] [Dipartimento di Scienze Fisiche e Chimiche, Università degli studi dell'Aquila, Via Vetoio, Coppito, 67100 L'Aquila (Italy)

2014-02-07

115

Derivative discontinuity, bandgap and lowest unoccupied molecular orbital in density functional theory.  

PubMed

The conventional analysis of Perdew and Levy, and Sham and Schlu?ter shows that the functional derivative discontinuity of the exchange-correlation density functional plays a critical role in the correct prediction of bandgaps, or the chemical hardness. In a recent work by the present authors, explicit expressions for bandgap prediction with all common types of exchange-correlation functionals have been derived without invoking the concept of exchange-correlation energy functional derivative discontinuity at all. We here analyze the two approaches and establish their connection and difference. The present analysis further leads to several important results: (1) The lowest unoccupied molecular orbital (LUMO) in DFT has as much meaning in describing electron addition as the highest occupied molecular orbital (HOMO) in describing electron removal. (2) Every term in the total energy functional contributes to the energy gap because of the discontinuity of the derivative of the density (or density matrix) with respect to the number of electrons, ((??(s)(r('),r))/?N)(v(s) ), at integers. (3) Consistent with the Perdew-Levy-Sham-Schlu?ter conclusion that the exact Kohn-Sham energy gap differs from the fundamental bandgap by a finite correction due to the functional derivative discontinuity of the exchange-correlation energy, we show that the exchange-correlation functional cannot be an explicit and differentiable functional of the electron density, either local or nonlocal. The last result is further strengthened when we consider Mott insulators. There, the exact exchange-correlation functional needs to have an explicitly discontinuous (nondifferentiable) dependence on the density or the density matrix. (4) We obtain exact conditions on the derivatives of total energy with respect to the spin-up and spin-down number of electrons. PMID:22667544

Yang, Weitao; Cohen, Aron J; Mori-Sánchez, Paula

2012-05-28

116

Orbital-dependent magnetic properties of molecular cluster containing high-spin Co(II) ions  

NASA Astrophysics Data System (ADS)

To shed light on magnetic properties of the magnetic exchange molecular cluster containing the constituent metal ion with unquenched orbital angular momentum, as representative examples two octahedrally coordinated high-spin Co(II)-cluster complexes were synthesized and characterized: complex (1) [Co3(Hbzp)6][ClO4]2· 2CH3OH·H2O (bzp = 2-benzoylpyridine) with a linear core Co(III)-Co(II)-Co(III) and complex (2) [Co4L(N3)4(CH3CN)4](ClO4)4·2H2O (L = Macrocyclic schiff base of tetra-2,6-pyridinedicarboxaldehyde-tetra-ethane-1,2-diamine) comprised by two nearly independent Co(II)-dimers. Following Lines' isotropic exchange approximation the magnetic interaction effective Hamiltonian was introduced, which includes the exchange interactions, the spin-orbit coupling, the low-symmetry crystal field, and the intercluster exchange interaction. On the basis of the irreducible tensor operator approach to solve Hamiltonian we have coded the software, BJMAG package, and performed the best-fit procedure for experimentally temperature variable magnetic susceptibilities for the complexes (1) and (2). The best-fit parameters were obtained as follows: ? = -126 cm-1, ? = 432 cm-1, ? = 0.96, mJ? = 2.7 cm-1 for the complex (1) and ? = -165 cm-1, ? = 960 cm-1, ? = 0.95, J? = 9 cm-1, mJ? = -0.1 cm-1 for the complex (2). To further elucidate the individual role of each interaction in the employed model, the effects of the key factors governing the magnetic properties on temperature variable magnetic susceptibilities were examined in detail. The significance of the intercluster exchange interactions at low temperatures was briefly discussed and a self-consistent molecular field to calculate the thermally average spin of the nearest neighbor in the intercluster interaction was proposed.

Wang, Fan; Zhao, Fei; Wang, Bing-Wu; Wang, Ming-Wei; Zhang, Yuan-Zhu; Wang, Wei; Gao, Song; Chen, Zhi-Da

117

Nonadiabatic ab initio molecular dynamics including spin-orbit coupling and laser fields.  

PubMed

Nonadiabatic ab initio molecular dynamics (MD) including spin-orbit coupling (SOC) and laser fields is investigated as a general tool for studies of excited-state processes. Up to now, SOCs are not included in standard ab initio MD packages. Therefore, transitions to triplet states cannot be treated in a straightforward way. Nevertheless, triplet states play an important role in a large variety of systems and can now be treated within the given framework. The laser interaction is treated on a non-perturbative level that allows nonlinear effects like strong Stark shifts to be considered. As MD allows for the handling of many atoms, the interplay between triplet and singlet states of large molecular systems will be accessible. In order to test the method, IBr is taken as a model system, where SOC plays a crucial role for the shape of the potential curves and thus the dynamics. Moreover, the influence of the nonresonant dynamic Stark effect is considered. The latter is capable of controlling reaction barriers by electric fields in time-reversible conditions, and thus a control laser using this effect acts like a photonic catalyst. In the IBr molecule, the branching ratio at an avoided crossing, which arises from SOC, can be influenced. PMID:22452086

Marquetand, Philipp; Richter, Martin; González-Vázquez, Jesús; Sola, Ignacio; González, Leticia

2011-01-01

118

Communication: Superatom molecular orbitals: new types of long-lived electronic states.  

PubMed

We present ab initio calculations of the quasiparticle decay times in a Buckminsterfullerene based on the many-body perturbation theory. A particularly lucid representation arises when the broadening of the quasiparticle states is plotted in the angular momentum (l) and energy (?) coordinates. In this representation the main spectroscopic features of the fullerene consist of two occupied nearly parabolic bands, and delocalized plane-wave-like unoccupied states with a few long-lived electronic states (the superatom molecular orbitals, SAMOs) embedded in the continuum of Fermi-liquid states. SAMOs have been recently uncovered experimentally by Feng et al. [Science 320, 359 (2008)] using scanning tunneling spectroscopy. The present calculations offer an explanation of their unusual stability and unveil their long-lived nature making them good candidates for applications in the molecular electronics. From the fundamental point of view these states illustrate a concept of the Fock-space localization [B. L. Altshuler, Y. Gefen, A. Kamenev, and L. S. Levitov, Phys. Rev. Lett. 78, 2803 (1997)] with properties drastically different from the Fermi-liquid excitations. PMID:22128920

Pavlyukh, Y; Berakdar, J

2011-11-28

119

On the energy invariance of open-shell perturbation theory with respect to unitary transformations of molecular orbitals  

E-print Network

On the energy invariance of open-shell perturbation theory with respect to unitary transformations of molecular orbitals T. Daniel Crawforda) and Henry F. Schaefer III Center for Computational Quantum Chemistry-reference open-shell perturbation theories based on a spin-restricted open-shell Hartree-Fock reference function

Crawford, T. Daniel

120

Spectroscopic mapping and selective electronic tuning of molecular orbitals in phosphorescent organometallic complexes – a new strategy for OLED materials  

PubMed Central

Summary The improvement of molecular electronic devices such as organic light-emitting diodes requires fundamental knowledge about the structural and electronic properties of the employed molecules as well as their interactions with neighboring molecules or interfaces. We show that highly resolved scanning tunneling microscopy (STM) and spectroscopy (STS) are powerful tools to correlate the electronic properties of phosphorescent complexes (i.e., triplet emitters) with their molecular structure as well as the local environment around a single molecule. We used spectroscopic mapping to visualize several occupied and unoccupied molecular frontier orbitals of Pt(II) complexes adsorbed on Au(111). The analysis showed that the molecules exhibit a peculiar localized strong hybridization that leads to partial depopulation of a dz² orbital, while the ligand orbitals are almost unchanged. We further found that substitution of functional groups at well-defined positions can alter specific molecular orbitals without influencing the others. The results open a path toward the tailored design of electronic and optical properties of triplet emitters by smart ligand substitution, which may improve the performance of future OLED devices. PMID:25551053

Ewen, Pascal R; Sanning, Jan; Koch, Tobias; Doltsinis, Nikos L

2014-01-01

121

Venn Diagrams  

NSDL National Science Digital Library

In this activity, students are given a Venn diagram with certain rules and an element. They must then determine where in the Venn diagram the element belongs. This activity allows students to practice placing elements in Venn diagrams as well as reviewing mathematical terms associated with the different rules. This activity includes supplemental materials, including background information about the topics covered, a description of how to use the application, and exploration questions for use with the java applet.

2010-01-01

122

Valence photoelectron spectroscopy of N2 and CO: recoil-induced rotational excitation, relative intensities, and atomic orbital composition of molecular orbitals.  

PubMed

Recoil-induced rotational excitation accompanying photoionization has been measured for the X, A, and B states of N(2)(+) and CO(+) over a range of photon energies from 60 to 900 eV. The mean recoil excitation increases linearly with the kinetic energy of the photoelectron, with slopes ranging from 0.73×10(-5) to 1.40×10(-5). These slopes are generally (but not completely) in accord with a simple model that treats the electrons as if they were emitted from isolated atoms. This treatment takes into account the atom from which the electron is emitted, the molecular-frame angular distribution of the electron, and the dependence of the photoelectron cross section on photon energy, on atomic identity, and on the type of atomic orbital from which the electron is ejected. These measurements thus provide a tool for investigating the atomic orbital composition of the molecular orbitals. Additional insight into this composition is obtained from the relative intensities of the various photolines in the spectrum and their variation with photon energy. Although there are some discrepancies between the predictions of the model and the observations, many of these can be understood qualitatively from a comparison of atomic and molecular wavefunctions. A quantum-mechanical treatment of recoil-induced excitation predicts an oscillatory variation with photon energy of the excitation. However, the predicted oscillations are small compared with the uncertainties in the data, and, as a result, the currently available results cannot provide confirmation of the quantum-mechanical theory. PMID:21054037

Thomas, T D; Kukk, E; Ouchi, T; Yamada, A; Fukuzawa, H; Ueda, K; Püttner, R; Higuchi, I; Tamenori, Y; Asahina, T; Kuze, N; Kato, H; Hoshino, M; Tanaka, H; Lindblad, A; Sæthre, L J

2010-11-01

123

Performance assessment of semiempirical molecular orbital methods in describing halogen bonding: quantum mechanical and quantum mechanical/molecular mechanical-molecular dynamics study.  

PubMed

The performance of semiempirical molecular-orbital methods--MNDO, MNDO-d, AM1, RM1, PM3 and PM6--in describing halogen bonding was evaluated, and the results were compared with molecular mechanical (MM) and quantum mechanical (QM) data. Three types of performance were assessed: (1) geometrical optimizations and binding energy calculations for 27 halogen-containing molecules complexed with various Lewis bases (Two of the tested methods, AM1 and RM1, gave results that agree with the QM data.); (2) charge distribution calculations for halobenzene molecules, determined by calculating the solvation free energies of the molecules relative to benzene in explicit and implicit generalized Born (GB) solvents (None of the methods gave results that agree with the experimental data.); and (3) appropriateness of the semiempirical methods in the hybrid quantum-mechanical/molecular-mechanical (QM/MM) scheme, investigated by studying the molecular inhibition of CK2 protein by eight halobenzimidazole and -benzotriazole derivatives using hybrid QM/MM molecular-dynamics (MD) simulations with the inhibitor described at the QM level by the AM1 method and the rest of the system described at the MM level. The pure MM approach with inclusion of an extra point of positive charge on the halogen atom approach gave better results than the hybrid QM/MM approach involving the AM1 method. Also, in comparison with the pure MM-GBSA (generalized Born surface area) binding energies and experimental data, the calculated QM/MM-GBSA binding energies of the inhibitors were improved by replacing the G(GB,QM/MM) solvation term with the corresponding G(GB,MM) term. PMID:21942911

Ibrahim, Mahmoud A A

2011-10-24

124

Magnetic phase diagram of a five-orbital Hubbard model in the real-space Hartree-Fock approximation varying the electronic density  

SciTech Connect

Usingthereal-spaceHartree-Fockapproximation,themagneticphasediagramofa ve-orbitalHubbardmodelfortheiron-basedsuperconductorsisstudiedvaryingtheelectronicdensitynintherangefrom vetosevenelectronspertransitionmetalatom.TheHubbardinteractionUisalsovaried,ata xedHundcouplingJ/U=0.25.Severalqualitativetrendsandavarietyofcompetingmagneticstatesareobserved.Atn=5,arobustG-typeantiferromagneticinsulatorisfound,inagreementwithexperimentalresultsforBaMn2As2.Asnincreasesawayfrom5,magneticstateswithanincreasingnumberofnearest-neighborsferromagneticlinksbecomeenergeticallystable.Thisincludesthewell-knownC-typeantiferromagneticstateatn=6,theE-phaseknowntoexistinFeTe,andalsoavarietyofnovelstatesnotfoundyetexperimentally,someoftheminvolvingblocksofferromagneticallyorientedspins.Regionsofphaseseparation,asinMnoxides,havealsobeendetected.Comparisontoprevioustheoreticalinvestigationsindicatethatthesequalitativetrendsmaybegenericcharacteristicsofphasediagramsofmulti-orbitalHubbardmodels.

Luo, Qinlong [ORNL] [ORNL; Dagotto, Elbio R [ORNL] [ORNL

2014-01-01

125

Venn Diagrams  

NSDL National Science Digital Library

This interactive problem provides an opportunity for children to become familiar with Venn diagrams, while reinforcing knowledge of number properties. Students must place the numbers from 1 to 40 into a Venn diagram of two sets with an intersection. The Teachers' Notes page offers rationale, suggestions for implementation, discussion questions, ideas for extension and support.

126

A rational reduction of CI expansions: combining localized molecular orbitals and selected charge excitations.  

PubMed

Based on localized molecular orbitals, the proposed method reduces large configuration interaction (CI) spaces while maintaining agreement with reference values. Our strategy concentrates the numerical effort on physically pertinent CI-contributions and is to be considered as a tool to tackle large systems including numerous open-shells. To show the efficiency of our method we consider two 4-electron parent systems. First, we illustrate our approach by describing the van der Waals interactions in the (H2)2 system. By systematically including local correlation, dispersion and charge transfer mechanisms, we show that 90% of the reference full CI dissociation energy of the H2 dimer is reproduced using only 3% of the full CI space. Second, the conformational cis/trans rotation barrier of the butadiene molecule is remarkably reproduced (97% of the reference value) with less than 1% of the reference space. This work paves the way to numerical strategies which afford the electronic structure determination of large open-shell systems avoiding the exponential limitation. At the same time, a physical analysis of the contents of the wave function is offered. PMID:24935105

Krah, Tim; Ben Amor, Nadia; Maynau, Daniel; Berger, J A; Robert, Vincent

2014-07-01

127

Spin-orbit interactionsand magnetic field in antiferromagnetic triangular molecular magnets  

NASA Astrophysics Data System (ADS)

Frustrated triangular molecular magnets such as Cu3 are characterized by a doubly generate S=1/2 ground-state (GS) with opposite chirality. Recently it has been proposed theoretically [1] and verified by ab-initio calculations [2] that an external electric field can efficiently couple these two chiral spin states, even in the absence of spin-orbit interaction (SOI). SOIs are nevertheless important, since they introduce a splitting in the GS manifold. In this talk we will discuss different schemes on how to evaluate within spin density functional theory the effect of the SOIs on the chiral states. The connection between SOI and the Dzyalozhinsky-Moriya interaction will be discussed. We will also present calculations of the energy dependence on an external magnetic field, whose presence is important to achieve full control of the spin-electric coupling within the manifold of the GS chiral doublets. [4pt] [1] M. Trif et. al. Phys. Rev. B 82, 045429 (2010) and M. Trif et. al. Phys. Rev. Lett. 101, 217201 (2008) [0pt] [2] F. Islam et. al. Phys. Rev. B 82, 155446 (2010)

Nossa, J. F.; Islam, M. F.; Canali, C. M.; Pederson, M. R.

2011-03-01

128

Ionization Potential, Electron Affinity, Electronegativity, Hardness, and Electron Excitation Energy: Molecular Properties from Density Functional Theory Orbital Energies  

Microsoft Academic Search

Representative atomic and molecular systems, including various inorganic and organic molecules with covalent and ionic bonds, have been studied by using density functional theory. The calculations were done with the commonly used exchange-correlation functional B3LYP followed by a comprehensive analysis of the calculated highest-occupied and lowest-unoccupied Kohn-Sham orbital (HOMO and LUMO) energies. The basis set dependence of the DFT results

Chang-Guo Zhan; Jeffrey A. Nichols; David A. Dixon

2003-01-01

129

The tetrahedral framework in glasses and melts — inferences from molecular orbital calculations and implications for structure, thermodynamics, and physical properties  

Microsoft Academic Search

Results of ab initio molecular orbital (MO) calculations provide a basis for the interpretation of structural and thermodynamic properties of crystals, glasses, and melts containing tetrahedrally coordinated Si, Al, and B. Calculated and experimental tetrahedral atom-oxygen (TO) bond lengths are in good agreement and the observed average SiO and AlO bond lengths remain relatively constant in crystalline, glassy, and molten

A. Navrotsky; K. L. Geisinger; P. McMillan; G. V. Gibbs

1985-01-01

130

Conformational analysis, spectroscopic study (FT-IR, FT-Raman, UV, 1H and 13C NMR), molecular orbital energy and NLO properties of 5-iodosalicylic acid  

NASA Astrophysics Data System (ADS)

In this study, 5-iodosalicylic acid (5-ISA, C7H5IO3) is structurally characterized by FT-IR, FT-Raman, NMR and UV spectroscopies. There are eight conformers, Cn, n = 1-8 for this molecule therefore the molecular geometry for these eight conformers in the ground state are calculated by using the ab-initio density functional theory (DFT) B3LYP method approach with the aug-cc-pVDZ-PP basis set for iodine and the aug-cc-pVDZ basis set for the other elements. The computational results identified that the most stable conformer of 5-ISA is the C1 form. The vibrational spectra are calculated DFT method invoking the same basis sets and fundamental vibrations are assigned on the basis of the total energy distribution (TED) of the vibrational modes, calculated with scaled quantum mechanics (SQM) method with PQS program. Total density of state (TDOS) and partial density of state (PDOS) and also overlap population density of state (COOP or OPDOS) diagrams analysis for C1 conformer were calculated using the same method. The energy and oscillator strength are calculated by time-dependent density functional theory (TD-DFT) results complement with the experimental findings. Besides, charge transfer occurring in the molecule between HOMO and LUMO energies, frontier energy gap, molecular electrostatic potential (MEP) are calculated and presented. The NMR chemical shifts (1H and 13C) spectra are recorded and calculated using the gauge independent atomic orbital (GIAO) method. Mulliken atomic charges of the title molecule are also calculated, interpreted and compared with salicylic acid. The optimized bond lengths, bond angles and calculated NMR and UV, vibrational wavenumbers showed the best agreement with the experimental results.

Karaca, Caglar; Atac, Ahmet; Karabacak, Mehmet

2015-02-01

131

Using Atomic Orbitals and Kinesthetic Learning to Authentically Derive Molecular Stretching Vibrations  

ERIC Educational Resources Information Center

The stretching modes of ML[subscript "x"] complexes have the same symmetry as the atomic orbitals on M that are used to form its s bonds. In the exercise suggested here, the atomic orbitals are used to derive the form of the stretching modes without the need for formal group theory. The analogy allows students to help understand many…

Bridgeman, Adam J.; Schmidt, Timothy W.; Young, Nigel A.

2013-01-01

132

Prediction of quantum interference in molecular junctions using a parabolic diagram: Understanding the origin of Fano and anti- resonances  

NASA Astrophysics Data System (ADS)

Recently the interest in quantum interference (QI) phenomena in molecular devices (molecular junctions) has been growing due to the unique features observed in the transmission spectra. In order to design single molecular devices exploiting QI effects as desired, it is necessary to provide simple rules for predicting the appearance of QI effects such as anti-resonances or Fano line shapes and for controlling them. In this study, we derive a transmission function of a generic molecular junction with a side group (T-shaped molecular junction) using a minimal toy model. We developed a simple method to predict the appearance of quantum interference, Fano resonances or anti- resonances, and its position in the conductance spectrum by introducing a simple graphical representation (parabolic model). Using it we can easily visualize the relation between the key electronic parameters and the positions of normal resonant peaks and anti-resonant peaks induced by quantum interference in the conductance spectrum. We also demonstrate Fano and anti-resonance in T-shaped molecular junctions using a simple tight-binding model. This parabolic model enables one to infer on-site energies of T-shaped molecules and the coupling between side group and main conduction channel from transmission spectra.

Nozaki, Daijiro; Avdoshenko, Stanislav M.; Sevinçli, Hâldun; Gutierrez, Rafael; Cuniberti, Gianaurelio

2013-03-01

133

Restricted active space calculations of L-edge X-ray absorption spectra: from molecular orbitals to multiplet states.  

PubMed

The metal L-edge (2p ? 3d) X-ray absorption spectra are affected by a number of different interactions: electron-electron repulsion, spin-orbit coupling, and charge transfer between metal and ligands, which makes the simulation of spectra challenging. The core restricted active space (RAS) method is an accurate and flexible approach that can be used to calculate X-ray spectra of a wide range of medium-sized systems without any symmetry constraints. Here, the applicability of the method is tested in detail by simulating three ferric (3d(5)) model systems with well-known electronic structure, viz., atomic Fe(3+), high-spin [FeCl6](3-) with ligand donor bonding, and low-spin [Fe(CN)6](3-) that also has metal backbonding. For these systems, the performance of the core RAS method, which does not require any system-dependent parameters, is comparable to that of the commonly used semi-empirical charge-transfer multiplet model. It handles orbitally degenerate ground states, accurately describes metal-ligand interactions, and includes both single and multiple excitations. The results are sensitive to the choice of orbitals in the active space and this sensitivity can be used to assign spectral features. A method has also been developed to analyze the calculated X-ray spectra using a chemically intuitive molecular orbital picture. PMID:25273421

Pinjari, Rahul V; Delcey, Mickaël G; Guo, Meiyuan; Odelius, Michael; Lundberg, Marcus

2014-09-28

134

Magnetic exchange between metal ions with unquenched orbital angular momenta: basic concepts and relevance to molecular magnetism  

NASA Astrophysics Data System (ADS)

This review article is a first attempt to give a systematic and comprehensive description (in the framework of the unified theoretical approach) of the exchange interactions in polynuclear systems based on orbitally degenerate metal ions in the context of their relevance to the modern molecular magnetism. Interest in these systems is related to the fundamental problems of magnetism and at the same time steered by a number of impressive potential applications of molecular magnets, like high-density memory storage units, nanoscale qubits, spintronics and photoswitchable devices. In the presence of orbital degeneracy, the conventional spin Hamiltonian (Heisenberg-Dirac-van Vleck model) becomes inapplicable even as an approximation. The central component of this review article constitutes the concept of orbitally-dependent exchange interaction between metal ions possessing unquenched orbital angular momenta. We present a rigorous procedure of derivation of the kinetic exchange Hamiltonian for a pair of orbitally degenerate transition metal ions that is expressed in terms of the orbital matrices and spin operators. The microscopic background reveals the interrelations between the parameters of the Hamiltonian and the internal parameters of the system including all relevant transfer integrals and fundamental intracenter interactions. The developed formalism integrated with the irreducible tensor operator (ITO) technique makes it possible to describe the exchange coupling and all relevant interactions (crystal fields, spin-orbit (SO) and Zeeman couplings) in terms of the ITOs of the full spherical group, and in this way to develop anunified and efficient computational tool. The orbitally-dependent exchange was shown to lead to an anomalously strong magnetic anisotropy that can be considered as a main physical manifestation of the unquenched orbital angular momentum in metal clusters of orbitally-degenerate ions. The theoretical background is illustrated by the following applications. The magnetic properties of the binuclear face-shared unit [Ti2Cl9]3- in Cs3Ti2Cl9 are discussed with the emphasis on the observed magnetic anisotropy and on the non-trivial symmetry properties of the exchange Hamiltonian. The major electronic factors controlling the magnetic anisotropy in Co(II) pairs are discussed. The degree of the exchange anisotropy was shown to depend on the strength of the cubic crystal field, on the relative efficiency of the electron transfer pathways between unfilled d-shells and SO coupling. Provided strong SO coupling, the effective Hamiltonian was projected onto the subspace of low-lying Kramers doublets and similarly a pseudo-spin-1/2 Hamiltonian was derived. The described procedure allows to establish the interrelation between idem parameters of the system and the parameters of the pseudo-spin-1/2 Hamiltonian. Pseudo-spin-1/2 approach is illustrated by the study of the inelastic neutron scattering spectra and magnetic susceptibility of polyoxometalates encapsulating Co(II) clusters: Keggin derivative K8[Co2(D2O)(W11O39)] · nD2O, [Co4(H2O)2(PW9O34)2]10- and [Co3W(D2O)2(CoW9O34)2]12- clusters. In the consideration of the cyanide-bridged Mn(III)-CN-Mn(II) pair, it was demonstrated that under certain conditions the orbitally-dependent exchange is able to produce a barrier for the reversal of magnetisation. This seems to be instructive for the controlled design of cyano-based single molecule magnets with high-blocking temperatures.

Palii, Andrei; Tsukerblat, Boris; Clemente-Juan, Juan Modesto; Coronado, Eugenio

135

Venn diagrams  

NSDL National Science Digital Library

These online resources offer varied opportunities to work with Venn diagrams, one of many tools used in logic and reasoning. Their use is especially helpful in learning foundational notions of definition and set theory. One of the five Process Standards promoted by NCTM, Reasoning and Proof requires middle school students to sharpen such skills as they learn to develop mathematical argument.

National Science Digital Library (NSDL) Middle School Portal Staff

2008-03-10

136

Unrestricted absolutely localized molecular orbitals for energy decomposition analysis: Theory and applications to intermolecular interactions involving radicals  

NASA Astrophysics Data System (ADS)

Radical-closed shell and radical-radical intermolecular interactions are less well-understood than those between closed shell species. With the objective of gaining additional insight, this work reports a generalization of the absolutely localized molecular orbital (ALMO) energy decomposition analysis (EDA) to open shell fragments, described by self-consistent field methods, such as standard density functional theory. The ALMO-EDA variationally partitions an intermolecular interaction energy into three separate contributions; frozen orbital interactions, polarization, and charge transfer. The first examples involve comparison of the interactions of alkanes and alkyl radicals (methyl radical, methane, tertiary butyl radical, and isobutane) with sodium, potassium, hydronium, and ammonium cations. A second series of examples involve benzene cation interacting with a series of nucleophiles in both on-top and side-on geometries. The ALMO-EDA yields a variety of interesting insights into the relative roles of its component contributions as the interacting partners and their geometries are changed.

Horn, Paul R.; Sundstrom, Eric Jon; Baker, Thomas A.; Head-Gordon, Martin

2013-04-01

137

Orbital hemorrhage and compressive optic neuropathy in patients with midfacial fractures receiving low-molecular weight heparin therapy.  

PubMed

While the implementation of deep vein thrombosis (DVT) prophylaxis in the hospital setting is a major concern, the use of antithrombotic agents is fraught with a variety of hemorrhagic complications. Due to increasing reports of adverse reactions to unfractionated heparin (UFH), several manufacturers have initiated product recalls. As a result, the use of low-molecular weight heparins (LMWHs) such as enoxaparin has risen substantially. In this paper, 2 orbital hemorrhagic complications in patients receiving enoxaparin therapy will be presented. The incidence of DVT in the OMS patient, recent prophylactic strategies, and their effectiveness will be reviewed. PMID:19531411

Jamal, Basem T; Diecidue, Robert J; Taub, Daniel; Champion, Allen; Bilyk, Jurij R

2009-07-01

138

A third-generation density-functional-theory-based method for calculating canonical molecular orbitals of large molecules.  

PubMed

We used grid-free modified Cholesky decomposition (CD) to develop a density-functional-theory (DFT)-based method for calculating the canonical molecular orbitals (CMOs) of large molecules. Our method can be used to calculate standard CMOs, analytically compute exchange-correlation terms, and maximise the capacity of next-generation supercomputers. Cholesky vectors were first analytically downscaled using low-rank pivoted CD and CD with adaptive metric (CDAM). The obtained Cholesky vectors were distributed and stored on each computer node in a parallel computer, and the Coulomb, Fock exchange, and pure exchange-correlation terms were calculated by multiplying the Cholesky vectors without evaluating molecular integrals in self-consistent field iterations. Our method enables DFT and massively distributed memory parallel computers to be used in order to very efficiently calculate the CMOs of large molecules. PMID:24622472

Hirano, Toshiyuki; Sato, Fumitoshi

2014-07-28

139

Orbital-free molecular dynamics simulations of a warm dense mixture: Examination of the excess-pressure matching rule  

SciTech Connect

A form of the linear mixing rule involving the equality of excess pressures is tested with various mole fractions and various types of orbital-free molecular dynamics simulations. For all the cases considered, this mixing rule yields, within statistical error, the pressure of a mixture of helium and iron obtained by a direct simulation. In an attempt to interpret the robustness of the mixing rule, we show that it can be derived from thermodynamic stability if the system is regarded as a mixture of independent effective average atoms. The success of the mixing rule applied with equations of state including various degrees of approximation leads us to suggest its use in the thermodynamic domain where quantum molecular dynamics can be implemented.

Danel, J-F.; Kazandjian, L.; Zerah, G. [Centre DAM Ile-de-France, CEA, Bruyeres-le-Chatel, 91297 Arpajon Cedex (France)

2009-06-15

140

A combined effective fragment potential-fragment molecular orbital method. I. The energy expression and initial applications  

NASA Astrophysics Data System (ADS)

The effective fragment potential (EFP) method, a model potential for treating solvent effects and other intermolecular interactions, is interfaced with an electronic structure method, the fragment molecular orbital (FMO) method, that is able to retain high accuracy for ab initio calculations on large molecular systems. The accuracy of the total energies in this novel combined FMO/EFP method is assessed by comparisons with the conventional quantum mechanics (QM)/EFP method. The test cases are water clusters, a peptide, and a dianionic protein (treated with full QM and FMO) combined with water clusters (treated with EFP) at the RHF, B3LYP, and MP2 levels of theory. The basis sets employed range from minimal to augmented double zeta plus polarization. The energy differences between FMO/EFP and the conventional QM/EFP methods are within "chemical accuracy" (1 kcal/mol?4 kJ/mol).

Nagata, Takeshi; Fedorov, Dmitri G.; Kitaura, Kazuo; Gordon, Mark S.

2009-07-01

141

Analytic energy gradient for second-order Møller-Plesset perturbation theory based on the fragment molecular orbital method.  

PubMed

The first derivative of the total energy with respect to nuclear coordinates (the energy gradient) in the fragment molecular orbital (FMO) method is applied to second order Møller-Plesset perturbation theory (MP2), resulting in the analytic derivative of the correlation energy in the external self-consistent electrostatic field. The completely analytic energy gradient equations are formulated at the FMO-MP2 level. Both for molecular clusters (H(2)O)(64) and a system with fragmentation across covalent bonds, a capped alanine decamer, the analytic FMO-MP2 energy gradients with the electrostatic dimer approximation are shown to be complete and accurate by comparing them with the corresponding numeric gradients. The developed gradient is parallelized with the parallel efficiency of about 97% on 32 Pentium4 nodes connected by Gigabit Ethernet. PMID:21806093

Nagata, Takeshi; Fedorov, Dmitri G; Ishimura, Kazuya; Kitaura, Kazuo

2011-07-28

142

Molecular structure, vibrational spectroscopic, hyperpolarizability, natural bond orbital analysis, frontier molecular orbital analysis and thermodynamic properties of 2,3,4,5,6-pentafluorophenylacetic acid.  

PubMed

The FT-IR (4000-400cm(-)(1)) and FT-Raman spectra (3500-100cm(-)(1)) of 2,3,4,5,6-pentafluorophenylacetic acid (PAA) have been recorded. Density functional theory calculation with LSDA/6-31+G(d,p) and B3LYP/6-31+G(d,p) basis sets have been used to determine ground state molecular geometries (bond lengths and bond angles), harmonic vibrational frequencies, infrared intensities, Raman intensities and bonding features of the title compound. The assignments of the vibrational spectra have been carried out with the help of normal coordinate analysis (NCA) following the scaled quantum mechanical force field (SQMFF) methodology. The first order hyperpolarizability (?0) and related properties (?, ?0 and ??) of PAA are calculated using B3LYP/6-31+G(d,p) method on the finite-field approach. The calculated first hyperpolarizability shows that the molecule is an attractive molecule for future applications in non-linear optics. The stability of molecule has been analyzed by using NBO analysis. The calculated HOMO and LUMO energies show that charge transfer occurs within this molecule. Mulliken population analysis on atomic charges is also calculated. Thermodynamic properties (heat capacity, enthalpy, Gibb's free energy and entropy) of the title compound at different temperatures were calculated. PMID:24662720

Balachandran, V; Karunakaran, V

2014-06-01

143

Molecular structure, vibrational spectroscopic, hyperpolarizability, natural bond orbital analysis, frontier molecular orbital analysis and thermodynamic properties of 2,3,4,5,6-pentafluorophenylacetic acid  

NASA Astrophysics Data System (ADS)

The FT-IR (4000-400 cm-1) and FT-Raman spectra (3500-100 cm-1) of 2,3,4,5,6-pentafluorophenylacetic acid (PAA) have been recorded. Density functional theory calculation with LSDA/6-31+G(d,p) and B3LYP/6-31+G(d,p) basis sets have been used to determine ground state molecular geometries (bond lengths and bond angles), harmonic vibrational frequencies, infrared intensities, Raman intensities and bonding features of the title compound. The assignments of the vibrational spectra have been carried out with the help of normal coordinate analysis (NCA) following the scaled quantum mechanical force field (SQMFF) methodology. The first order hyperpolarizability (?0) and related properties (?, ?0 and ??) of PAA are calculated using B3LYP/6-31+G(d,p) method on the finite-field approach. The calculated first hyperpolarizability shows that the molecule is an attractive molecule for future applications in non-linear optics. The stability of molecule has been analyzed by using NBO analysis. The calculated HOMO and LUMO energies show that charge transfer occurs within this molecule. Mulliken population analysis on atomic charges is also calculated. Thermodynamic properties (heat capacity, enthalpy, Gibb's free energy and entropy) of the title compound at different temperatures were calculated.

Balachandran, V.; Karunakaran, V.

2014-06-01

144

Demystifying Introductory Chemistry. Part 2: Bonding and Molecular Geometry Without Orbitals--the Electron Domain Model.  

ERIC Educational Resources Information Center

Presents an alternative approach to bonding and geometry--the electron domain model--which avoids some of the problems with the conventional approach. Discusses difficulties with the orbital model at the introductory level, electron spin and the Pauli exclusion principle, electron pair domains, nonequivalent domains, multiple bonds, and origins…

Gillespie, Ronald J.; And Others

1996-01-01

145

Quantitative Structure-Toxicity Relationships for Chlorophenols to Bioluminescent Lux-Marked Bacteria Using Atom-Based SemiEmpirical Molecular-Orbital Descriptors  

Microsoft Academic Search

Literature data on the toxicity of chlorophenols for three luminescent bacteria (Vibrio fischeri, and the lux-marked Pseudomonas fluorescens 10586spUCD607 and Burkholderia spp. RASC c2 (Tn4431)) have been analysed in relation to a set of computed molecular physico-chemical properties. The quantitative structure-toxicity relationships of the compounds in each species showed marked differences when based upon semi-empirical molecular-orbital molecular and atom based

M. A. Warne; E. M. Boyd; A. A. Meharg; D. Osborn; K. Killham; J. C. Lindon; J. K. Nicholson

1999-01-01

146

Beyond the spin model: exchange coupling in molecular magnets with unquenched orbital angular momenta.  

PubMed

In this critical review we review the problem of exchange interactions in polynuclear metal complexes involving orbitally degenerate metal ions. The key feature of these systems is that, in general, they carry an unquenched orbital angular momentum that manifests itself in all their magnetic properties. Thus, interest in degenerate systems involves fundamental problems related to basic models in magnetism. In particular, the conventional Heisenberg-Dirac-Van Vleck model becomes inapplicable even as an approximation. In the first part we attempt to answer two key questions, namely which theoretical tools are to be used in the case of degeneracy, and how these tools can be employed. We demonstrate that the exchange interaction between orbitally degenerate metal ions can be described by the so-called orbitally-dependent exchange Hamiltonian. This approach has shown to reveal an anomalously strong magnetic anisotropy that can be considered as the main physical manifestation of the unquenched orbital angular momentum in magnetic systems. Along with the exchange coupling, a set of other interactions (such as crystal field effects, spin-orbit and Zeeman coupling), which are specific for the degenerate systems, need to be considered. All these features will be discussed in detail using a pseudo-spin-1/2 Hamiltonian approach. In the second part, the described theoretical background will be used to account for the magnetic properties of several magnetic metal clusters and low-dimensional systems: (i) the dinuclear face-sharing unit [Ti(2)Cl(9)](3-), which exhibits a large magnetic anisotropy; (ii) the rare-earth compounds Cs(3)Yb(2)Cl(9) and Cs(3)Yb(2)Br(9), which, surprisingly, exhibit a full magnetic isotropy; (iii) a zig-zag Co(II) chain exhibiting unusual combination of single-chain magnet behavior and antiferromagnetic exchange coupling; (iv) a trigonal bipyramidal Ni(3)Os(2) complex; (v) various Co(II) clusters encapsulated by polyoxometalate ligands. In the two last examples a pseudospin-1/2 Hamiltonian approach is applied to account for the presence of exchange anisotropy (150 references). PMID:21431145

Palii, Andrei; Tsukerblat, Boris; Klokishner, Sophia; Dunbar, Kim R; Clemente-Juan, Juan M; Coronado, Eugenio

2011-06-01

147

Gas-phase ultraviolet photoelectron spectroscopy and molecular orbital calculations on transition metal carbonyls and nitrosyls  

E-print Network

16 a&6 I I bq ~ll b I I bq 15bu I I au 14bu l5ac5 15 bu ~14bu u 15bu 14bul lau ~15 a 14aq 39 ~fi re 10. photoelect o ap ct a of th [00MPC0)070 o pl ea (M=Cr, Mo, W). [C p Cr (C 0)2]2 [Cp Mo(CQ)2]2 [Cp W(C0), ], I 1 I I I I I I 7 8 9... ~ )i I ' ea' Ila" Cp le "u tl / / n / / ll l5a / p rL /I // '&IOa" l4a'. -I5. 0? eV Metal MO Ligand Figure 2. Mo1ecu1ar orbita1 diagram of (n -C H )Cr(NO) C1. The energy 5 values were obtained from a Fenske-Ha11 ca1cuIa)ion. The dashed 1...

Morris-Sherwood, Betty Jeanne

2012-06-07

148

Phase diagram of Ag-Pd bimetallic nanoclusters by molecular dynamics simulations: solid-to-liquid transition and size-dependent behavior.  

PubMed

This report on the solid-to-liquid transition region of an Ag-Pd bimetallic nanocluster is based on a constant energy microcanonical ensemble molecular dynamics simulation combined with a collision method. By varying the size and composition of an Ag-Pd bimetallic cluster, we obtained a complete solid-solution type of binary phase diagram of the Ag-Pd system. Irrespective of the size and composition of the cluster, the melting temperature of Ag-Pd bimetallic clusters is lower than that of the bulk state and rises as the cluster size and the Pd composition increase. Additionally, the slope of the phase boundaries (even though not exactly linear) is lowered when the cluster size is reduced on account of the complex relations of the surface tension, the bulk melting temperature, and the heat of fusion. The melting of the cluster initially starts at the surface layer. The initiation and propagation of a five-fold icosahedron symmetry is related to the sequential melting of the cluster. PMID:19562138

Kim, Da Hye; Kim, Hyun You; Ryu, Ji Hoon; Lee, Hyuck Mo

2009-07-01

149

Growth diagram of N-face GaN (0001¯) grown at high rate by plasma-assisted molecular beam epitaxy  

NASA Astrophysics Data System (ADS)

N-face GaN was grown on free-standing GaN (0001¯) substrates at a growth rate of 1.5 ?m/h using plasma-assisted molecular beam epitaxy. Difference in growth rate between (0001¯) and (0001) oriented GaN depends on nitrogen plasma power, and the (0001¯) oriented GaN had only 70% of the growth rate of the (0001) oriented GaN at 300 W. Unintentional impurity concentrations of silicon, carbon, and oxygen were 2 × 1015, 2 × 1016, and 7 × 1016 cm-3, respectively. A growth diagram was constructed that shows the dependence of the growth modes on the difference in the Ga and active nitrogen flux, ?Ga - ?N*, and the growth temperature. At high ?Ga - ?N* (?Ga ? ?N*), two-dimensional (step-flow and layer-by-layer) growth modes were realized. High growth temperature (780 °C) expanded the growth window of the two-dimensional growth modes, achieving a surface with rms roughness of 0.48 nm without Ga droplets.

Okumura, Hironori; McSkimming, Brian M.; Huault, Thomas; Chaix, Catherine; Speck, James S.

2014-01-01

150

Growth diagram of N-face GaN (0001{sup ¯}) grown at high rate by plasma-assisted molecular beam epitaxy  

SciTech Connect

N-face GaN was grown on free-standing GaN (0001{sup ¯}) substrates at a growth rate of 1.5??m/h using plasma-assisted molecular beam epitaxy. Difference in growth rate between (0001{sup ¯}) and (0001) oriented GaN depends on nitrogen plasma power, and the (0001{sup ¯}) oriented GaN had only 70% of the growth rate of the (0001) oriented GaN at 300?W. Unintentional impurity concentrations of silicon, carbon, and oxygen were 2?×?10{sup 15}, 2?×?10{sup 16}, and 7?×?10{sup 16}?cm{sup ?3}, respectively. A growth diagram was constructed that shows the dependence of the growth modes on the difference in the Ga and active nitrogen flux, ?{sub Ga}????{sub N*}, and the growth temperature. At high ?{sub Ga}????{sub N*} (?{sub Ga}????{sub N*}), two-dimensional (step-flow and layer-by-layer) growth modes were realized. High growth temperature (780?°C) expanded the growth window of the two-dimensional growth modes, achieving a surface with rms roughness of 0.48?nm without Ga droplets.

Okumura, Hironori, E-mail: okumura@engineering.ucsb.edu; McSkimming, Brian M.; Speck, James S. [Materials Department, University of California, Santa Barbara, California 93106 (United States)] [Materials Department, University of California, Santa Barbara, California 93106 (United States); Huault, Thomas; Chaix, Catherine [RIBER S.A., 3a Rue Casimir Perier, BP 70083, 95873 Bezons Cedex (France)] [RIBER S.A., 3a Rue Casimir Perier, BP 70083, 95873 Bezons Cedex (France)

2014-01-06

151

Molecular orbital calculations on transition metal dimers containing a linear dinitrogen bridge  

E-print Network

is also the order of decreasing bond length as determined by x-ray crystallography. Our calculations suggest that more electrons are donated into the u-N }v system in the Nb, Zr and Re-Mo cases because of the presence 2 g of unoccupied dv orbitals... strengths are enhanced by synergetic o donation in the Nb dimer. DEDI GATI OI'I To my parents, Dr. and Mrs. John M. Barton&and to Greg and 8ethany ACKNOWLEDGMENTS I wish to thank Professor Michael B. Hall for his guidance and encouragement during my...

Powell, Mary Cynthia

1984-01-01

152

Theory of molecular-orbital and compound-nucleus x-ray emission in heavy-ion-atom collisions with nuclear sticking  

Microsoft Academic Search

Calculations are made of x-ray emission in head-on 200-MeV (lab) Ni+Ni and 860-MeV (lab) Yb+Yb collisions for various values of the compound nucleus lifetime?. TheK x-ray emission probability is obtained by coherently summing the amplitude for a molecular-orbital x-ray transition from the 2p?, 2p?, 3p?, or 3p? to the 1s? molecular orbital with the amplitude for a compound-nucleus x-ray transition

R. Anholt

1979-01-01

153

Theoretical investigation of EPR and molecular orbital coefficient parameters for [Cu(hsm) 2(sac) 2] complex  

NASA Astrophysics Data System (ADS)

In this study, the molecular orbital coefficients and the spin Hamiltonian parameters of bis(histamine-saccharinate) copper(II) complex, [Cu(hsm) 2(sac) 2], are calculated theoretically. Two d- d transition spectra and four EPR parameters g?,g?,A?,A? for the Cu(II) complex are calculated by using crystal-field theory. The calculated values are in good agreement with the experimental values. The g and A parameters have indicated that the paramagnetic centre is axially symmetric. Having the relations of g?>g?>ge and A?>A? for Cu 2+ ions, it can be concluded that Cu 2+ ions are located in distorted octahedral sites (D 4h) elongated along the z-axis and that the ground state of the paramagnetic electron is d ( 2B1g state).

Kalfao?lu, Emel; Karabulut, Bünyamin

2011-03-01

154

Efficient implementation of the three-dimensional reference interaction site model method in the fragment molecular orbital method  

SciTech Connect

The three-dimensional reference interaction site model (3D-RISM) method was efficiently implemented in the fragment molecular orbital (FMO) method. The method is referred to as the FMO/3D-RISM method, and allows us to treat electronic structure of the whole of a macromolecule, such as a protein, as well as the solvent distribution around a solute macromolecule. The formalism of the FMO/3D-RISM method, for the computationally available form and variational expressions, are proposed in detail. A major concern leading to the implementation of the method was decreasing the computational costs involved in calculating the electrostatic potential, because the electrostatic potential is calculated on numerous grid points in three-dimensional real space in the 3D-RISM method. In this article, we propose a procedure for decreasing the computational costs involved in calculating the electrostatic potential in the FMO method framework. The strategy involved in this procedure is to evaluate the electrostatic potential and the solvated Fock matrix in different manners, depending on the distance between the solute and the solvent. The electrostatic potential is evaluated directly in the vicinity of the solute molecule by integrating the molecular orbitals of monomer fragments of the solute molecule, whereas the electrostatic potential is described as the sum of multipole interactions when an analog of the fast multipole method is used. The efficiency of our method was demonstrated by applying it to a water trimer system and three biomolecular systems. The FMO/3D-RISM calculation can be performed within a reasonable computational time, retaining the accuracy of some physical properties.

Yoshida, Norio, E-mail: noriwo@chem.kyushu-univ.jp [Department of Chemistry, Graduate School of Sciences, Kyushu University, 6-10-1, Hakozaki, Higashi-ku, Fukuoka 812-8581 (Japan)

2014-06-07

155

Length-dependence of intramolecular electron transfer in ?-bonded rigid molecular rods: an ab initio molecular orbital study  

NASA Astrophysics Data System (ADS)

The dependence of electron transfer (ET) coupling element, VAB, on the length of rigid-rod-like systems consisting of bicyclo[1.1.1]pentane (BCP), cubane (CUB), and bicyclo[2.2.2]octane (BCO) monomers, has been investigated with the use of ab initio Hartree-Fock (HF) method employing Marcus-Hush two-state (TS) model. The value of VAB decreases exponentially with increase in the number of the cage units of the ?-bonded molecules. The calculated decay constant, ?, shows good agreement with previously reported data. For molecular length?15 Å, the value of VAB becomes negligibly small, suggesting complete suppression of the through bond direct tunneling contribution to ET process.

Pati, Ranjit; Karna, Shashi P.

2002-01-01

156

An orbital-free self-consistent field approach for molecular clusters and liquids  

E-print Network

We present an ``orbital'' free density functional theory for computing the quantum ground state of atomic clusters and liquids. Our approach combines the Bohm hydrodynamical description of quantum mechanics with an information theoretical approach to determine an optimal quantum density function in terms of density approximates to a statistical sample. The ideas of Bayesian statistical analysis and an expectation-maximization procedure are combined to develop approximations to the quantum density and thus find the approximate quantum force. The quantum force is then combined with a Lennard-Jones force to simulate clusters of Argon atoms and to obtain the ground state configurations and energies. As demonstration of the utility and flexibility of the approach, we compute the lowest energy structures for small rare-glass clusters. Extensions to many atom systems is straightforward.

Sean W. Derrickson; Eric R. Bittner

2005-10-31

157

Controlling the Interference of Multiple Molecular Orbitals in High-Harmonic Generation  

SciTech Connect

We demonstrate a new method to investigate the origin of spectral structures in high-harmonic generation. We report detailed measurements of high-harmonic spectra in aligned nitrogen and carbon dioxide molecules. Varying the wavelength and intensity of the generating laser field, we show that the minimum in aligned N{sub 2} molecules is nearly unaffected, whereas the minimum in aligned CO{sub 2} molecules shifts over more than 15 eV. Our quantitative analysis shows that both the interference of multiple orbitals and their structural characteristics affect the position of the minimum. Our method provides a simple approach to the investigation of the high-harmonic generation process in more complex molecules.

Woerner, H. J.; Bertrand, J. B.; Hockett, P.; Corkum, P. B.; Villeneuve, D. M. [Joint Laboratory for Attosecond Science, National Research Council of Canada and University of Ottawa, 100 Sussex Drive, Ottawa, Ontario, K1A 0R6 (Canada)

2010-06-11

158

Communication: Localized molecular orbital analysis of the effect of electron correlation on the anomalous isotope effect in the NMR spin-spin coupling constant in methane  

NASA Astrophysics Data System (ADS)

We discuss the effect of electron correlation on the unexpected differential sensitivity (UDS) in the 1J(C-H) coupling constant of CH4 using a decomposition into contributions from localized molecular orbitals and compare with the 1J(N-H) coupling constant in NH3. In particular, we discuss the well known fact that uncorrelated coupled Hartree-Fock (CHF) calculations are not able to reproduce the UDS in methane. For this purpose we have implemented for the first time a localized molecular orbital analysis for the second order polarization propagator approximation with coupled cluster singles and doubles amplitudes—SOPPA(CCSD) in the DALTON program. Comparing the changes in the localized orbital contributions at the correlated SOPPA and SOPPA(CCSD) levels and at the uncorrelated CHF level, we find that the latter overestimates the effect of stretching the bond between the coupled atoms on the contribution to the coupling from the localized bonding orbital between these atoms. This disturbs the subtle balance between the molecular orbital contributions, which lead to the UDS in methane.

Zarycz, M. Natalia C.; Sauer, Stephan P. A.; Provasi, Patricio F.

2014-10-01

159

Theoretical study of intramolecular interaction energies during dynamics simulations of oligopeptides by the fragment molecular orbital-Hamiltonian algorithm method  

NASA Astrophysics Data System (ADS)

We analyzed the interaction energies between residues (fragments) in an oligopeptide occurring during dynamic simulations by using the fragment molecular orbital-Hamiltonian algorithm (FMO-HA) method, an ab initio MO-molecular dynamics technique. The FMO method enables not only calculation of large molecules based on ab initio MO but also easy evaluation of interfragment interaction energies. The glycine pentamer [(Gly)5] and decamer [(Gly)10] were divided into five and ten fragments, respectively. ?-helix structures of (Gly)5 and (Gly)10 were stabilized by attractive interaction energies owing to intramolecular hydrogen bonds between fragments n and n +3 (and n +4), and ?-strand structures were characterized by repulsive interaction energies between fragments n and n +2. We analyzed interfragment interaction energies during dynamics simulations as the peptides' geometries changed from ? helix to ? strand. Intramolecular hydrogen bonds between fragments 2-4 and 2-5 control the geometrical preference of (Gly)5 for the ?-strand structure. The pitch of one turn of the ? helix of (Gly)10 elongated and thus weakened during dynamics due to a shifting of the intramolecular hydrogen bonds, and enabled the ?-strand structure to form. Changes in interaction energies due to the intramolecular hydrogen bonds controlled the tendency toward ?-helix or ?-strand structure of (Gly)5 and (Gly)10. Evaluation of interfragment interaction energies during dynamics simulations thus enabled detailed analysis of the process of the geometrical changes occurring in oligopeptides.

Ishimoto, Takayoshi; Tokiwa, Hiroaki; Teramae, Hiroyuki; Nagashima, Umpei

2005-03-01

160

The Spin-orbit force, recoil corrections and possible $B \\bar{B}^{*}$ and $D \\bar{D}^{*}$ molecular states  

E-print Network

In the framework of the one boson exchange model, we have calculated the effective potentials between two heavy mesons $B \\bar{B}^{*}$ and $D \\bar{D}^{*}$ from the t- and u-channel $\\pi$, $\\eta$, $\\rho$, $\\omega$ and $\\sigma$ meson exchange with four kinds of quantum number: $I=0$, $J^{PC}=1^{++}$; $I=0$, $J^{PC}=1^{+-}$; $I=1$, $J^{PC}=1^{++}$; $I=1$, $J^{PC}=1^{+-}$. We keep the recoil corrections to the $B \\bar{B}^{*}$ and $D \\bar{D}^{*}$ system up to $O(\\frac{1}{M^2})$. The spin orbit force appears at $O(\\frac{1}{M})$, which turns out to be important for the very loosely bound molecular states. Our numerical results show that the momentum-related corrections are unfavorable to the formation of the molecular states in the $I=0$, $J^{PC}=1^{++}$ and $I=1$, $J^{PC}=1^{+-}$ channels in the $D \\bar{D}^{*}$ systems.

Lu Zhao; Li Ma; Shi-Lin Zhu

2014-03-19

161

Density functional and spin-orbit ab initio study of CF3Br: molecular properties and electronic curve crossing.  

PubMed

Quantum chemical calculations of CF(3)Br and the CF(3) radical are performed using density functional theory (DFT) and time-dependent DFT (TDDFT). Molecular structures, vibrational frequencies, dipole moment, bond dissociation energy, and vertical excitation energies of CF(3)Br are calculated and compared with available experimental results. The performance of six hybrid and five hybrid meta functionals in DFT and TDDFT calculations are evaluated. The ?B97X, B3PW91, and M05-2X functionals give very good results for molecular structures, vibrational frequencies, and vertical excitation energies, respectively. The ?B97X functional calculates well the dipole moment of CF(3)Br. B3LYP, one of the most widely used functionals, does not perform well for calculations of the C-Br bond length, bond dissociation energy, and vertical excitation energies. Potential energy curves of the low-lying excited states of CF(3)Br are obtained using the multiconfigurational spin-orbit ab initio method. The crossing point between 2A(1) and 3E states is located near the C-Br bond length of 2.45 Å. Comparison with CH(3)Br shows that fluorination does not alter the location of the crossing point. The relation between the calculated potential energy curves and recent experimental result is briefly discussed. PMID:21271728

Kim, Joonghan; Kim, Tae Kyu; Ihee, Hyotcherl

2011-02-24

162

A new hierarchical parallelization scheme: generalized distributed data interface (GDDI), and an application to the fragment molecular orbital method (FMO).  

PubMed

A two-level hierarchical scheme, generalized distributed data interface (GDDI), implemented into GAMESS is presented. Parallelization is accomplished first at the upper level by assigning computational tasks to groups. Then each group does parallelization at the lower level, by dividing its task into smaller work loads. The types of computations that can be used with this scheme are limited to those for which nearly independent tasks and subtasks can be assigned. Typical examples implemented, tested, and analyzed in this work are numeric derivatives and the fragment molecular orbital method (FMO) that is used to compute large molecules quantum mechanically by dividing them into fragments. Numeric derivatives can be used for algorithms based on them, such as geometry optimizations, saddle-point searches, frequency analyses, etc. This new hierarchical scheme is found to be a flexible tool easily utilizing network topology and delivering excellent performance even on slow networks. In one of the typical tests, on 16 nodes the scalability of GDDI is 1.7 times better than that of the standard parallelization scheme DDI and on 128 nodes GDDI is 93 times faster than DDI (on a multihub Fast Ethernet network). FMO delivered scalability of 80-90% on 128 nodes, depending on the molecular system (water clusters and a protein). A numerical gradient calculation for a water cluster achieved a scalability of 70% on 128 nodes. It is expected that GDDI will become a preferred tool on massively parallel computers for appropriate computational tasks. PMID:15011259

Fedorov, Dmitri G; Olson, Ryan M; Kitaura, Kazuo; Gordon, Mark S; Koseki, Shiro

2004-04-30

163

Comparison of the local structural stabilities of mammalian prion protein (PrP) by fragment molecular orbital calculations  

PubMed Central

Bovine spongiform encephalopathy (BSE), a member of the prion diseases, is a fatal neurodegenerative disorder suspected to be caused by a malfunction of prion protein (PrP). Although BSE prions have been reported to be transmitted to a wide range of animal species, dogs and hamsters are known to be BSE-resistant animals. Analysis of canine and hamster PrP could elucidate the molecular mechanisms supporting the species barriers to BSE prion transmission. The structural stability of 6 mammalian PrPs, including human, cattle, mouse, hamster, dog and cat, was analyzed. We then evaluated intramolecular interactions in PrP by fragment molecular orbital (FMO) calculations. Despite similar backbone structures, the PrP side-chain orientations differed among the animal species examined. The pair interaction energies between secondary structural elements in the PrPs varied considerably, indicating that the local structural stabilities of PrP varied among the different animal species. Principal component analysis (PCA) demonstrated that different local structural stability exists in bovine PrP compared with the PrP of other animal species examined. The results of the present study suggest that differences in local structural stabilities between canine and bovine PrP link diversity in susceptibility to BSE prion infection. PMID:23232497

Hasegawa, Koji; Mohri, Shirou; Yokoyama, Takashi

2013-01-01

164

Protein-specific force field derived from the fragment molecular orbital method can improve protein-ligand binding interactions.  

PubMed

Accurate computational estimate of the protein-ligand binding affinity is of central importance in rational drug design. To improve accuracy of the molecular mechanics (MM) force field (FF) for protein-ligand simulations, we use a protein-specific FF derived by the fragment molecular orbital (FMO) method and by the restrained electrostatic potential (RESP) method. Applying this FMO-RESP method to two proteins, dodecin, and lysozyme, we found that protein-specific partial charges tend to differ more significantly from the standard AMBER charges for isolated charged atoms. We did not see the dependence of partial charges on the secondary structure. Computing the binding affinities of dodecin with five ligands by MM PBSA protocol with the FMO-RESP charge set as well as with the standard AMBER charges, we found that the former gives better correlation with experimental affinities than the latter. While, for lysozyme with five ligands, both charge sets gave similar and relatively accurate estimates of binding affinities. PMID:23420697

Chang, Le; Ishikawa, Takeshi; Kuwata, Kazuo; Takada, Shoji

2013-05-30

165

Molecular structure, vibrational spectra, natural bond orbital and thermodynamic analysis of 3,6-dichloro-4-methylpyridazine and 3,6-dichloropyridazine-4-carboxylic acid by dft approach  

NASA Astrophysics Data System (ADS)

Vibrational spectral analysis of the molecules 3,6-dichloro-4-methylpyridazine (DMP) and 3,6-dichloropyridazine-4-carboxylic acid (DPC) was carried out using FT-IR and FT-Raman spectroscopic techniques. The molecular structure and vibrational spectra of DMP and DPC were obtained by the density functional theory (DFT) method, using B3LYP functional, with 6-311++G(d,p) basis set. A detailed interpretation of the Infrared and Raman spectra of the two molecules were reported based on potential energy distribution (PED). The theoretically predicted FTIR and FT-Raman spectra of the titled molecules have been simulated and were compared with the experimental spectra. Determination of electric dipole moment (?) and hyperpolarizability ?0 helps to study the non-linear optical (NLO) behavior of DMP and DPC. Stability of the molecules arising from hyperconjugative interactions, charge delocalization have been analyzed using natural bond orbital (NBO) analysis. 13C and 1H NMR spectra were recorded and 13C and 1H NMR chemical shifts of the molecules were calculated using the gauge independent atomic orbital (GIAO) method. UV-visible spectrum of the compounds was also recorded in the region 200-1100 nm and electronic properties, HOMO (Highest Occupied Molecular Orbitals) and LUMO (Lowest Unoccupied Molecular Orbitals) energies were measured by time-dependent TD-DFT approach. Charge density distribution and site of chemical reactivity of the molecule have been studied by mapping electron density isosurface with molecular electrostatic potential (MESP).

Prabavathi, N.; Senthil Nayaki, N.; Venkatram Reddy, B.

2015-02-01

166

A New Class of Mixed-Valence Systems with Orbitally Degenerate Organic Redox Centers. Examples Based on Hexa-Rhenium Molecular Prisms  

E-print Network

Based on Hexa-Rhenium Molecular Prisms Peter H. Dinolfo,, Veaceslav Coropceanu,§ Jean-Luc Bre.2 Here, we report the MV properties of two supramolecular com- plexes: triangular prisms of the form by direct overlap of donor and acceptor orbitals.3 Surprisingly, the prisms display significant differences

167

QSPR modeling of the enthalpy of formation from elements by means of correlation weighting of local invariants of atomic orbital molecular graphs  

Microsoft Academic Search

A quantitative structure–property modeling of the enthalpy of formation from elements by means of correlation weighting of local invariants of atomic orbital molecular graphs (AOMGs) is presented. The method is applied to a set comprising 51 hydrocarbon molecules and results are quite good, with lower average deviations than experimental uncertainties. Some possible applications and further extensions of the calculation procedure

Andrés Mercader; Eduardo A. Castro; Andrey A. Toropov

2000-01-01

168

Synthesis, Structure, and Molecular Orbital Studies of Yttrium, Erbium, and Lutetium Complexes Bearing 2-Pyrazolato Ligands: Development of a New Class of Precursors for  

E-print Network

Synthesis, Structure, and Molecular Orbital Studies of Yttrium, Erbium, and Lutetium Complexes procedure, the reaction of erbium metal with 3,5-dialkylpyrazole (alkyl ) methyl or tert-butyl), bis-tert-butylpyrazole) yielded tris(3,5-di-tert-butylpyrazolato)bis(4-tert-butylpy- ridine)erbium(III) (63%), tris(3,5-di-tert-butylpyrazolato)bis(pyridine)erbium

Schlegel, H. Bernhard

169

Molecular structure, vibrational spectra, natural bond orbital and thermodynamic analysis of 3,6-dichloro-4-methylpyridazine and 3,6-dichloropyridazine-4-carboxylic acid by dft approach.  

PubMed

Vibrational spectral analysis of the molecules 3,6-dichloro-4-methylpyridazine (DMP) and 3,6-dichloropyridazine-4-carboxylic acid (DPC) was carried out using FT-IR and FT-Raman spectroscopic techniques. The molecular structure and vibrational spectra of DMP and DPC were obtained by the density functional theory (DFT) method, using B3LYP functional, with 6-311++G(d,p) basis set. A detailed interpretation of the Infrared and Raman spectra of the two molecules were reported based on potential energy distribution (PED). The theoretically predicted FTIR and FT-Raman spectra of the titled molecules have been simulated and were compared with the experimental spectra. Determination of electric dipole moment (?) and hyperpolarizability ?0 helps to study the non-linear optical (NLO) behavior of DMP and DPC. Stability of the molecules arising from hyperconjugative interactions, charge delocalization have been analyzed using natural bond orbital (NBO) analysis. (13)C and (1)H NMR spectra were recorded and (13)C and (1)H NMR chemical shifts of the molecules were calculated using the gauge independent atomic orbital (GIAO) method. UV-visible spectrum of the compounds was also recorded in the region 200-1100nm and electronic properties, HOMO (Highest Occupied Molecular Orbitals) and LUMO (Lowest Unoccupied Molecular Orbitals) energies were measured by time-dependent TD-DFT approach. Charge density distribution and site of chemical reactivity of the molecule have been studied by mapping electron density isosurface with molecular electrostatic potential (MESP). PMID:25459510

Prabavathi, N; Senthil Nayaki, N; Venkatram Reddy, B

2015-02-01

170

Molecular-orbital decomposition of the ionization continuum for a diatomic molecule by angle-and energy-resolved photoelectron spectroscopy.  

E-print Network

the NO A 2 0 state to each partial wave in the ionization continuum that yields the NO X 1 0 ion, provideMolecular-orbital decomposition of the ionization continuum for a diatomic molecule by angle distributions PADs from the direct photoionization of a diatomic molecule in which both the ionizing state

Zare, Richard N.

171

Studies of the molecular geometry, vibrational spectra, frontier molecular orbital, nonlinear optical and thermodynamics properties of aceclofenac by quantum chemical calculations.  

PubMed

The solid phase FT-IR and FT-Raman spectra of 2-[2-[2-[(2,6-dichlorophenyl)amino]phenyl]acetyl] oxyacetic acid (Aceclofenac) have been recorded in the region 4000-400 and 4000-100 cm(-1) respectively. The optimized molecular geometry and fundamental vibrational frequencies are interpreted with the aid of structure optimizations and normal coordinate force field calculations based on density functional theory (DFT) method and a comparative study between Hartree Fork (HF) method 6-311++G(d,p) level basis set. The calculated harmonic vibrational frequencies were scaled and have been compared with experimental by obtained FT-IR and FT-Raman spectra. A detailed interpretation of the vibrational spectra of this compound has been made on the basis of the calculated potential energy distribution (PED). The time dependent DFT method employed to study its absorption energy and oscillator strength. The linear polarizability (?) and the first order hyper polarizability (?) values of the investigated molecule have been computed. The electronic properties, such as HOMO and LUMO energies, molecular electrostatic potential (MESP) were also performed. Stability of the molecule arising from hyper conjugative interaction, charge delocalization has been analyzed using natural bond orbital (NBO) analysis. PMID:24556133

Suresh, S; Gunasekaran, S; Srinivasan, S

2014-05-01

172

Studies of the molecular geometry, vibrational spectra, Frontier molecular orbital, nonlinear optical and thermodynamics properties of Aceclofenac by quantum chemical calculations  

NASA Astrophysics Data System (ADS)

The solid phase FT-IR and FT-Raman spectra of 2-[2-[2-[(2,6-dichlorophenyl)amino]phenyl]acetyl] oxyacetic acid (Aceclofenac) have been recorded in the region 4000-400 and 4000-100 cm-1 respectively. The optimized molecular geometry and fundamental vibrational frequencies are interpreted with the aid of structure optimizations and normal coordinate force field calculations based on density functional theory (DFT) method and a comparative study between Hartree Fork (HF) method 6-311++G(d,p) level basis set. The calculated harmonic vibrational frequencies were scaled and have been compared with experimental by obtained FT-IR and FT-Raman spectra. A detailed interpretation of the vibrational spectra of this compound has been made on the basis of the calculated potential energy distribution (PED). The time dependent DFT method employed to study its absorption energy and oscillator strength. The linear polarizability (?) and the first order hyper polarizability (?) values of the investigated molecule have been computed. The electronic properties, such as HOMO and LUMO energies, molecular electrostatic potential (MESP) were also performed. Stability of the molecule arising from hyper conjugative interaction, charge delocalization has been analyzed using natural bond orbital (NBO) analysis.

Suresh, S.; Gunasekaran, S.; Srinivasan, S.

173

Molecular orbital analysis of the inverse halogen dependence of nuclear magnetic shielding in LaX?, X = F, Cl, Br, I.  

PubMed

The NMR nuclear shielding tensors for the series LaX(3), with X = F, Cl, Br and I, have been computed using two-component relativistic density functional theory based on the zeroth-order regular approximation (ZORA). A detailed analysis of the inverse halogen dependence (IHD) of the La shielding was performed via decomposition of the shielding tensor elements into contributions from localized and delocalized molecular orbitals. Both spin-orbit and paramagnetic shielding terms are important, with the paramagnetic terms being dominant. Major contributions to the IHD can be attributed to the La-X bonding orbitals, as well as to trends associated with the La core and halogen lone pair orbitals, the latter being related to X-La ? donation. An 'orbital rotation' model for the in-plane ? acceptor f orbital of La helps to rationalize the significant magnitude of deshielding associated with the in-plane ? donation. The IHD goes along with a large increase in the shielding tensor anisotropy as X becomes heavier, which can be associated with trends for the covalency of the La-X bonds, with a particularly effective transfer of spin-orbit coupling induced spin density from iodine to La in LaI(3). PMID:20586110

Moncho, Salvador; Autschbach, Jochen

2010-12-01

174

Stereochemical diversity of {MNO}(10) complexes: molecular orbital analyses of nickel and copper nitrosyls.  

PubMed

The great majority of {NiNO}(10) complexes are characterized by short Ni-N(O) distances of 1.60-1.65 Å and linear NO units. Against this backdrop, the {CuNO}(10) unit in the recently reported [Cu(CH3NO2)5(NO)](2+) cation (1) has a CuNO angle of about 120° and a very long 1.96 Å Cu-N(O) bond. According to DFT calculations, metal-NO bonding in 1 consists of a single Cu(dz(2))-NO(?*) ?-interaction and essentially no metal(d?)-NO(?*) ?-bonding, which explains both the bent CuNO geometry and the long, weak Cu-N(O) bond. This ?-interaction is strongly favored by a ligand trans to the NO; indeed such a trans ligand may be critical for the existence and stability of a {CuNO}(10) unit. By contrast, {NiNO}(10) complexes exhibit a strong avoidance of such trans ligands. Thus, a five-coordinate {NiNO}(10) complex appears to favor a trigonal-bipyramidal structure with the NO in an equatorial position, as in the case of [Ni(bipy)2(NO)](+) (6). An unusual set of Ni(d)-NO(?*) orbital interactions accounts for the strongly bent NiNO geometry for this complex. PMID:24796643

Conradie, Jeanet; Ghosh, Abhik

2014-05-19

175

Spectroscopic studies, potential energy surface and molecular orbital calculations of pramipexole.  

PubMed

A systematic vibrational spectroscopic assignment and analysis of pramipexole [(S)-N(6)-propyl-4,5,6,7-tetrahydro-1,3-benzothiazole-2,6-diamine] has been carried out using FT-IR and FT-Raman spectral data. The vibrational analysis was aided by an electronic structure calculation based on the hybrid density functional method B3LYP using a 6-311G(d, p) and cc-pVTZ basis sets. Molecular equilibrium geometries, electronic energies, IR and Raman intensities, harmonic vibrational frequencies have been computed. The assignments are based on the experimental IR and Raman spectra, and a complete assignment of the observed spectra has been proposed. The UV-visible spectrum of the compound was recorded and the electronic properties, such as HOMO and LUMO energies and the maximum absorption ?max were determined by time-dependent DFT (TD-DFT) method. The geometrical parameters, vibrational frequencies and absorption wavelengths were compared with the experimental data. The complete vibrational assignments are performed on the basis of the potential energy distributions (PEDs) of the vibrational modes in terms of natural internal coordinates. The simulated FT-IR, FT-Raman, and UV spectra of the title compound have been constructed. In addition, the potential energy surface, HOMO and LUMO energies, the molecular electrostatic potential and the first-order hyperpolarizability have been computed. The magnitude of the first-order hyperpolarizability is 5 times larger than that of urea and the title compound may be a potential applicant for the development of NLO materials. PMID:23831980

Muthu, S; Uma Maheswari, J; Srinivasan, S; Isac paulraj, E

2013-11-01

176

Spin-orbit effects calculated by a configuration interaction method using determinants of two-component molecular spinors: test calculations on Rn and T1H  

NASA Astrophysics Data System (ADS)

We are developing a relativistic configuration interaction (RCI) method for polyatomic molecules using relativistic effective core potentials (REP). The present RCI method incorporates spin-orbit interactions from the HF step through the use of two-component molecular spinors confirming Kramers' degeneracy. Test calculations for the low-lying excited states of the Rn atom and the ground state of T1H demonstrate that the present RCI method has some advantages over the conventional RCI methods using the same REP but introducing spin-orbit terms only at the CI steps.

Kim, Myeong Cheol; Lee, Sang Yeon; Lee, Yoon Sup

1996-05-01

177

A QSAR study on the inhibition mechanism of matrix metalloproteinase-12 by arylsulfone analogs based on molecular orbital calculations.  

PubMed

A binding mechanism between human matrix metalloproteinase-12 (MMP-12) and eight arylsulfone analogs having two types of carboxylic and hydroxamic acids as the most representative zinc binding group is investigated using a quantitative structure-activity relationship (QSAR) analysis based on a linear expression by representative energy terms (LERE). The LERE-QSAR analysis quantitatively reveals that the variation in the observed (experimental) inhibitory potency among the arylsulfone analogs is decisively governed by those in the intrinsic binding and dispersion interaction energies. The results show that the LERE-QSAR analysis not only can excellently reproduce the observed overall free-energy change but also can determine the contributions of representative free-energy changes. An inter-fragment interaction energy difference (IFIED) analysis based on the fragment molecular orbital (FMO) method (FMO-IFIED) leads to the identification of key residues governing the variation in the inhibitory potency as well as to the understanding of the difference between the interactions of the carboxylic and hydroxamic acid zinc binding groups. The current results that have led to the optimization of the inhibitory potency of arylsulfone analogs toward MMP-12 to be used in the treatment of chronic obstructive pulmonary disease may be useful for the development of a new potent MMP-12 inhibitor. PMID:25406681

Hitaoka, Seiji; Chuman, Hiroshi; Yoshizawa, Kazunari

2015-01-21

178

An ab initio molecular orbital study on adsorption at the MgO surface. III. Cooperativity of ionic adsorbates  

NASA Astrophysics Data System (ADS)

The cooperativity between coadsorbed molecules on the MgO surface was investigated with the ab initio molecular orbital (MO) method using (MgO)4 and (MgO)6 clusters as models of the catalytic surface. On the pair of three-coordinate sites, the H2, NH3, or H2O molecule is chemisorbed heterolytically, like H--Mg-O-H+, H2N--Mg-O-H+, or HO--Mg-O-H+. When the two adsorbate molecules are cochemisorbed on the adjacent set of four three-coordinate sites, the total chemisorption energy is much larger than the sum of chemisorption energies of each molecule. The extra stability, i.e., the energy cooperativity, is almost the same, around 20 kcal/mol, regardless of the adsorbed species, as far as both of them are heterolytically chemisorbed. The H2-CO coadsorbed system, in which CO is adsorbed nondissociatively, shows no cooperativity. The cooperativity above is partly due to the electrostatic attraction between the coadsorbed ionic species and partly due to the enhanced charge transfer (CT) interaction. Based on these results, it is suggested that higher coordination sites, inactive for chemisorption by themselves, may be activated by preadsorption at the neighboring pair of three-coordinate sites and may actually be ``the active catalytic site'' on the MgO surface.

Sawabe, Kyoichi; Morokuma, Keiji; Iwasawa, Yasuhiro

1994-10-01

179

Exciton analysis of many-body wave functions: Bridging the gap between the quasiparticle and molecular orbital pictures  

NASA Astrophysics Data System (ADS)

Exciton sizes and electron-hole binding energies, which are central properties of excited states in extended systems and crucial to the design of modern electronic devices, are readily defined within a quasiparticle framework but are quite challenging to understand in the molecular-orbital picture. The intent of this work is to bridge this gap by providing a general way of extracting the exciton wave function out of a many-body wave function obtained by a quantum chemical excited-state computation. This methodology, which is based on the one-particle transition density matrix, is implemented within the ab initio algebraic diagrammatic construction scheme for the polarization propagator and specifically the evaluation of exciton sizes, i.e., dynamic charge separation distances, is considered. A number of examples are presented. For stacked dimers it is shown that the exciton size for charge separated states corresponds to the intermolecular separation, while it only depends on the monomer size for locally excited states or Frenkel excitons. In the case of conjugated organic polymers, the tool is applied to analyze exciton structure and dynamic charge separation. Furthermore, it is discussed how the methodology may be used for the construction of a charge-transfer diagnostic for time-dependent density-functional theory.

Bäppler, Stefanie A.; Plasser, Felix; Wormit, Michael; Dreuw, Andreas

2014-11-01

180

Molecular orbital calculations of proton transfer involving amines as models for the clastic binding of opiates with their receptor  

SciTech Connect

Semi-empirical (CNDO) molecular orbital calculations, based on a previously reported ammonia-amine model system, were performed on an extended series of methyl-, ethyl-, and propylamines as models for the analgesic receptor. Methyl-, dimethyl-, and trimethylamines were chosen to represent the opiate molecules. Interatomic distances were varied within normally expected biological values. The results for the larger systems are similar to more elaborate calculations previously reported using smaller molecules. At internuclear distances of greater than 0.275 nm, the potential energy curves had two minima. At 0.2731 nm, the optimized N-N distance, the depth of the minima in the potential energy curve were not as great. Energy differences as well as population differences suggest deviation from the currently stated clastic binding theories mechanism for the analgesic response of the tertiary amines. The dimethylamine energy profile and population data indicate that the hypothesis of N-demethylated opiate as the active molecule needs further consideration and investigation. Investigation of larger systems is also indicated to develop increasingly realistic models for the analgesic response.

Bennett, L.K.; Beamer, R.L.

1986-08-01

181

Automatic Diagrams Analysis  

Microsoft Academic Search

This paper presents fully automatic approach analysis for information extraction from digitized grey level images of scanned diagrams in the field of graphics recognition. The proposed algorithms were tested on Telecom Egypt diagrams and some randomly selected diagrams. The analysis involves three distinct stages: the location of starting pixels in the diagrams; followed by a model based line-following to separate

M. A. Berbar

2006-01-01

182

Quantitative Structure-Cytotoxicity Relationship of Bioactive Heterocycles by the Semi-empirical Molecular Orbital Method with the Concept of Absolute Hardness  

NASA Astrophysics Data System (ADS)

The relationship between the cytotoxicity of N-heterocycles (13 4-trifluoromethylimidazole, 15 phenoxazine and 12 5-trifluoromethyloxazole derivatives), O-heterocycles (11 3-formylchromone and 20 coumarin derivatives) and seven vitamin K2 derivatives against eight tumor cell lines (HSC-2, HSC-3, HSC-4, T98G, HSG, HepG2, HL-60, MT-4) and a maximum of 15 chemical descriptors was investigated using CAChe Worksystem 4.9 project reader. After determination of the conformation of these compounds and approximation to the molecular form present in vivo (biomimetic) by CONFLEX5, the most stable structure was determined by CAChe Worksystem 4.9 MOPAC (PM3). The present study demonstrates the best relationship between the cytotoxic activity and molecular shape or molecular weight of these compounds. Their biological activities can be estimated by hardness and softness, and by using ?-? activity diagrams.

Ishihara, Mariko; Sakagami, Hiroshi; Kawase, Masami; Motohashi, Noboru

183

Theoretical investigation on the non-linear optical properties, vibrational spectroscopy and frontier molecular orbital of (E)-2-cyano-3-(3-hydroxyphenyl)acrylamide molecule  

NASA Astrophysics Data System (ADS)

The vibrational frequencies of (E)-2-cyano-3-(3-hydroxyphenyl)acrylamide (HB-CA) in the ground state have been calculated using density functional method (B3LYP) with B3LYP/6-311++G(d,p) basis set. The analysis of natural bond orbital was also performed. The IR spectra were obtained and interpreted by means of potential energies distributions (PEDs) using MOLVIB program. In addition, the results show that there exists Csbnd H⋯O hydrogen bond in the title compound, which is confirmed by the natural bond orbital analysis. The predicted NLO properties show that the title compound is a good candidate as nonlinear optical material. The analysis of frontier molecular orbitals shows that HB-CA has high excitation energies, good stability and high chemical hardness. The analysis of MEP map shows the negative and the positive potential sites.

Xiao-Hong, Li; Hong-Ling, Cui; Rui-Zhou, Zhang; Xian-Zhou, Zhang

2015-02-01

184

Theoretical investigation on the non-linear optical properties, vibrational spectroscopy and frontier molecular orbital of (E)-2-cyano-3-(3-hydroxyphenyl)acrylamide molecule.  

PubMed

The vibrational frequencies of (E)-2-cyano-3-(3-hydroxyphenyl)acrylamide (HB-CA) in the ground state have been calculated using density functional method (B3LYP) with B3LYP/6-311++G(d,p) basis set. The analysis of natural bond orbital was also performed. The IR spectra were obtained and interpreted by means of potential energies distributions (PEDs) using MOLVIB program. In addition, the results show that there exists CH?O hydrogen bond in the title compound, which is confirmed by the natural bond orbital analysis. The predicted NLO properties show that the title compound is a good candidate as nonlinear optical material. The analysis of frontier molecular orbitals shows that HB-CA has high excitation energies, good stability and high chemical hardness. The analysis of MEP map shows the negative and the positive potential sites. PMID:25228040

Xiao-Hong, Li; Hong-Ling, Cui; Rui-Zhou, Zhang; Xian-Zhou, Zhang

2015-02-25

185

Photoelectron spectra and molecular orbital calculations of dicarbonyl- and dinitrosyl-bridged cobalt, rhodium and iridium cyclopentadienyl dimers and of disulfido- and diselenido-nonacarbonyltriosmium  

E-print Network

PHOTOELECTRON SPECTRA AND MOLECULAR ORBITAL CALCULATIONS OF DICARBONYL- AND DINITROSYL-BRIDGED COBALT, RHODIUM AND IRIDIUM CYCLOPENTADIENYL DIMERS AND OF DISULFIDO- AND DISELENIDO-NONACARBONYLTRIOSMIUM. A Thesis by GREG LEWIS GRIEWE Submitted...-BRIDGED COBALT, RHODIUM AND IRIDIUM CYCLOPENTADIENYL DIMERS AND OF DISULFIDO- AND DISELENIDO-NONACARBONYLTRIOSMIUM. A Thesis by GREG LEWIS GRIEWE Approved as to style and content by: Michael B. Hall (Chairman) M rcetta arensbo rg (Member) James R. Wild...

Griewe, Greg Lewis

1987-01-01

186

A molecular orbital study of a model of the Mg2+ coordination complex of the self splicing reaction of ribosomal RNA  

NASA Technical Reports Server (NTRS)

Recent discoveries have established the fact that RNA is capable of acting as an enzyme. In this study two different types of molecular orbital calculations, INDO and ab initio, were used in an attempt to assess the structural/functional role of the Mg2+ hydrated complex in ribozyme reactions. Preliminary studies indicate that the reaction is multistep and that the Mg2+ complex exerts a stabilizing effect on the intermediate or midpoint of the reaction.

McCourt, M.; Shibata, M.; McIver, J. W.; Rein, R.

1988-01-01

187

Gravity and Orbits: Orbits  

NSDL National Science Digital Library

This Science Object is the third of three Science Objects in the Gravity and Orbits SciPack. It provides an understanding of how gravitational forces influence the motion of an object in orbit. When a force acts toward a single center, an object's forward motion and its motion toward that center can combine to create a curved path around the center. Gravity governs the motion of all objects in the solar system. The Sun's gravitational pull holds the Earth and other planets in their orbits, just as the planets' gravitational pull keeps their moons in orbit around them. Learning Outcomes:? Describe the conditions that would lead an object into orbital motion in terms of the effects of gravitational force.? Explain how an object orbits a planet in terms of trajectories and free fall.? Identify gravity as the force that keeps the planets in their orbits around the Sun and the moons in their orbits around the planets.

National Science Teachers Association (NSTA)

2006-11-01

188

On the separability of the extended molecule: Constructing the best localized molecular orbitals for an organic molecule bridging two model electrodes.  

PubMed

Based on a quantum chemical valence formalism that allows the rigorous construction of best-localized molecular orbitals on specific parts of an extended system, we examined the separability of individual components of model systems relevant to the description of electron transport in molecular devices. We started by examining how to construct the maximally localized electronic density at the tip of a realistic model of a gold electrode. By varying the number of gold atoms included in the local region where to project the total electronic density, we quantitatively assess how many molecular orbitals are entirely localized in that region. We then considered a 1,4-benzene-di-thiol molecule connected to two model gold electrodes and examined how to localize the electronic density of the total system in the extended molecule, a fractional entity comprising the organic molecule plus an increasing number of the closest metal atoms. We were able to identify in a rigorous manner the existence of three physically different electronic populations, each one corresponding to a distinct set of molecular orbitals. First, there are those entirely localized in the extended molecule, then there is a second group of those completely distributed in the gold atoms external to that region, and, finally, there are those delocalized over the entire system. This latter group can be associated to the shared electronic population between the extended molecule and the rest of the system. We suggest that the treatment here presented could be useful in the theoretical analysis of the electronic transport in nanodevices whenever the use of localized molecular states are required by the physics of the specific problem, such as in cases of weak coupling and super-exchange limits. PMID:25273466

Moreira, Rodrigo A; de Melo, Celso P

2014-09-28

189

On the separability of the extended molecule: Constructing the best localized molecular orbitals for an organic molecule bridging two model electrodes  

NASA Astrophysics Data System (ADS)

Based on a quantum chemical valence formalism that allows the rigorous construction of best-localized molecular orbitals on specific parts of an extended system, we examined the separability of individual components of model systems relevant to the description of electron transport in molecular devices. We started by examining how to construct the maximally localized electronic density at the tip of a realistic model of a gold electrode. By varying the number of gold atoms included in the local region where to project the total electronic density, we quantitatively assess how many molecular orbitals are entirely localized in that region. We then considered a 1,4-benzene-di-thiol molecule connected to two model gold electrodes and examined how to localize the electronic density of the total system in the extended molecule, a fractional entity comprising the organic molecule plus an increasing number of the closest metal atoms. We were able to identify in a rigorous manner the existence of three physically different electronic populations, each one corresponding to a distinct set of molecular orbitals. First, there are those entirely localized in the extended molecule, then there is a second group of those completely distributed in the gold atoms external to that region, and, finally, there are those delocalized over the entire system. This latter group can be associated to the shared electronic population between the extended molecule and the rest of the system. We suggest that the treatment here presented could be useful in the theoretical analysis of the electronic transport in nanodevices whenever the use of localized molecular states are required by the physics of the specific problem, such as in cases of weak coupling and super-exchange limits.

Moreira, Rodrigo A.; de Melo, Celso P.

2014-09-01

190

Tree Diagrams and Probability  

NSDL National Science Digital Library

This lesson is designed to develop students' ability to create tree diagrams and figure probabilities of events based on those diagrams. This lesson provides links to discussions and activities related to tree diagrams as well as suggested ways to work them into the lesson. Finally, the lesson provides links to follow-up lessons designed for use in succession with the current one.

2011-01-20

191

Phase Equilibria Diagrams Database  

National Institute of Standards and Technology Data Gateway

SRD 31 NIST/ACerS Phase Equilibria Diagrams Database (PC database for purchase)   The Phase Equilibria Diagrams Database contains commentaries and more than 21,000 diagrams for non-organic systems, including those published in all 21 hard-copy volumes produced as part of the ACerS-NIST Phase Equilibria Diagrams Program (formerly titled Phase Diagrams for Ceramists): Volumes I through XIV (blue books); Annuals 91, 92, 93; High Tc Superconductors I & II; Zirconium & Zirconia Systems; and Electronic Ceramics I. Materials covered include oxides as well as non-oxide systems such as chalcogenides and pnictides, phosphates, salt systems, and mixed systems of these classes.

192

Equation of state of a dense plasma by orbital-free and quantum molecular dynamics: Examination of two isothermal-isobaric mixing rules  

NASA Astrophysics Data System (ADS)

We test two isothermal-isobaric mixing rules, respectively based on excess-pressure and total-pressure equilibration, applied to the equation of state of a dense plasma. While the equation of state is generally known for pure species, that of arbitrary mixtures is not available so that the validation of accurate mixing rules, that implies resorting to first-principles simulations, is very useful. Here we consider the case of a plastic with composition C2H3 and we implement two complementary ab initio approaches adapted to the dense plasma domain: quantum molecular dynamics, limited to low temperature by its computational cost, and orbital-free molecular dynamics, that can be implemented at high temperature. The temperature and density range considered is 1-10 eV and 0.6-10 g/cm 3 for quantum molecular dynamics, and 5-1000 eV and 1-10 g/cm 3 for orbital-free molecular dynamics. Simulations for the full C2H3 mixture are the benchmark against which to assess the mixing rules, and both pressure and internal energy are compared. We find that the mixing rule based on excess-pressure equilibration is overall more accurate than that based on total-pressure equilibration; except for quantum molecular dynamics and a thermodynamic domain characterized by very low or negative excess pressures, it gives pressures which are generally within statistical error or within 1% of the exact ones. Besides, its superiority is amplified in the calculation of a principal Hugoniot.

Danel, J.-F.; Kazandjian, L.

2015-01-01

193

Symmetry and broken-symmetry in molecular orbital descriptions of unstable molecules. 3. The nature of chemical bonds of spin frustrated systems.  

PubMed

Symmetry and broken symmetry in the molecular orbital description of spin frustration systems have been investigated in relation to the resonating valence bond (RVB) theory of the spin liquid state and non-BCS superconductivity. Broken symmetry (BS) and resonating BS (RBS) molecular orbital (MO) methods have been employed to obtain resonating valence bond (RVB)-type explanations of spin frustrated systems. RBS MO solutions are expanded using the localized molecular orbitals (LMO) to elucidate a universal MO-VB description. The BS and RBS MO descriptions of triangular spin frustrated systems corresponding to transition structures for exchange-forbidden radical insertions were investigated in comparison with the RVB-type explanations of such systems. The BS and RBS calculations by the use of three different axial (SDW) solutions or three noncollinear GSO (helical SDW) solutions of a triangular hydrogen cluster were performed to obtain potential curves with and without resonance (quantum) effects. The resonating GSO (noncollinear) state responsible for short-range correlation was found to be the most stable for the system. The reliability of the approximate spin projection (AP) procedure to eliminate the high-spin component was also elucidated, comparing with the AP BS and RBS potential curves. The BS GSO (GHF) computations of several triangular systems, N(CH(2))(3), (CH(2))(3), and Mn(II)(3)O(4), were performed to obtain total energies and total spin angular momentums and effective exchange integrals (J) between local spins, which are crucial for construction of effective spin Hamiltonian models. The exact diagonalization of the Heisenberg models was also performed to depict the energy levels and magnetic susceptibility curves for triangular and kagome lattices to elucidate spin frustration effects and related quantum spin behaviors. Implications of the computational results have been discussed in relation to magnetic properties of several triangular and kagome systems synthesized recently and the superconductivity of triangular systems discovered recently. PMID:19908878

Kawakami, T; Takeda, R; Nishihara, S; Saito, T; Shoji, M; Yamada, S; Yamanaka, S; Kitagawa, Y; Okumura, M; Yamaguchi, K

2009-12-31

194

A THIRD LOOK AT WEIGHT DIAGRAMS Nikolai Vavilov  

E-print Network

at the Isaac Newton Institute for Mathematical Sciences. Typeset by A M S­T E X 1 #12; 2 nikolai vavilov of root subgroups and of the extended Weyl group, multilinear invariants, equations defining the orbit diagrams, crystal graphs, signs of structure constants, unipotent root elements, multilinear forms, orbit

Bielefeld, University of

195

Energetic Studies and Phase Diagram of Thioxanthene  

NASA Astrophysics Data System (ADS)

The molecular stability of thioxanthene, a key species from which very important compounds with industrial relevance are derived, has been studied by a combination of several experimental techniques and computational approaches. The standard (p° = 0.1 MPa) molar enthalpy of formation of crystalline thioxanthene (117.4 ± 4.1 kJ·mol-1) was determined from the experimental standard molar energy of combustion, in oxygen, measured by rotating-bomb combustion calorimetry at T = 298.15 K. The enthalpy of sublimation was determined by a direct method, using the vacuum drop microcalorimetric technique, and also by an indirect method, using a static apparatus, where the vapor pressures at different temperatures were measured. The latter technique was used for both crystalline and undercooled liquid samples, and the phase diagram of thioxanthene near the triple point was obtained (triple point coordinates T = 402.71 K and p = 144.7 Pa). From the two methods, a mean value for the standard (p° = 0.1 MPa) molar enthalpy of sublimation, at T = 298.15 K (101.3 ± 0.8 kJ·mol-1), was derived. From the latter value and from the enthalpy of formation of the solid, the standard (p° = 0.1 MPa) enthalpy of formation of gaseous thioxanthene was calculated as 218.7 ± 4.2 kJ·mol-1. Standard ab initio molecular orbital calculations were performed using the G3(MP2)//B3LYP composite procedure and several homodesmotic reactions in order to derive the standard molar enthalpy of formation of thioxanthene. The ab initio results are in excellent agreement with the experimental data.

Freitas, Vera L. S.; Monte, Manuel J. S.; Santos, Luís M. N. B. F.; Gomes, José R. B.; Ribeiro da Silva, Maria D. M. C.

2009-10-01

196

Unrestricted density functional theory based on the fragment molecular orbital method for the ground and excited state calculations of large systems  

SciTech Connect

We extended the fragment molecular orbital (FMO) method interfaced with density functional theory (DFT) into spin unrestricted formalism (UDFT) and developed energy gradients for the ground state and single point excited state energies based on time-dependent DFT. The accuracy of FMO is evaluated in comparison to the full calculations without fragmentation. Electronic excitations in solvated organic radicals and in the blue copper protein, plastocyanin (PDB code: 1BXV), are reported. The contributions of solvent molecules to the electronic excitations are analyzed in terms of the fragment polarization and quantum effects such as interfragment charge transfer.

Nakata, Hiroya, E-mail: nakata.h.ab@m.titech.ac.jp [Center for Biological Resources and Informatics, Tokyo Institute of Technology, B-62 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8501 (Japan) [Center for Biological Resources and Informatics, Tokyo Institute of Technology, B-62 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8501 (Japan); RIKEN, Research Cluster for Innovation, Nakamura Lab, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Fedorov, Dmitri G. [NRI, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568 (Japan)] [NRI, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568 (Japan); Yokojima, Satoshi [RIKEN, Research Cluster for Innovation, Nakamura Lab, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan) [RIKEN, Research Cluster for Innovation, Nakamura Lab, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Tokyo University of Pharmacy and Life Sciences, 1423-1 Horinouchi, Hachioji-shi, Tokyo 192-0392 (Japan); Kitaura, Kazuo [Graduate School of System Informatics, Kobe University, 1-1 Rokkodai-cho, Nada-ku, Kobe 657-8501 (Japan)] [Graduate School of System Informatics, Kobe University, 1-1 Rokkodai-cho, Nada-ku, Kobe 657-8501 (Japan); Sakurai, Minoru [Center for Biological Resources and Informatics, Tokyo Institute of Technology, B-62 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8501 (Japan)] [Center for Biological Resources and Informatics, Tokyo Institute of Technology, B-62 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8501 (Japan); Nakamura, Shinichiro [RIKEN, Research Cluster for Innovation, Nakamura Lab, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan)] [RIKEN, Research Cluster for Innovation, Nakamura Lab, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan)

2014-04-14

197

Building Venn Diagrams  

NSDL National Science Digital Library

In this lesson plan students watch a video clip of Bianca as she uses Venn diagrams to try to satisfy three people's preferences in pizza toppings. Students practice using Venn diagrams to represent the pizza topping preferences. Learners are then introduced to prime numbers, prime factorization, and the use of Venn diagrams to determine least common multiple and greatest common factor. Support materials are included: Handout: Gleamers and Glow Power, Assessment: Levels A and B and answer keys are provided.

2007-01-01

198

16O + 16O + valence neutrons in molecular orbitals structures of positive- and negative-parity superdeformed bands in 34S  

NASA Astrophysics Data System (ADS)

The structures of superdeformed (SD) states in 34S are investigated using the antisymmetrized molecular dynamics and generator coordinate method (GCM). The GCM basis wave functions are calculated via energy variation with a constraint on the quadrupole deformation parameter ?. By applying the GCM after parity and angular momentum projections, the coexistence of two positive- and one negative-parity SD bands are predicted, and low-lying states and other deformed bands are obtained. The SD bands have structures of 16O + 16O + two valence neutrons in molecular orbitals around the two 16O cores in a cluster picture. The configurations of the two valence neutrons are ?2 and ?2 for the positive-parity SD bands and ?1?1 for the negative-parity SD band.

Taniguchi, Yasutaka

2014-12-01

199

Mass Transport Properties of LiD-U Mixtures from Orbital Free Molecular Dynamics Simulations and a Pressure-Matching Mixing Rule  

SciTech Connect

Mass transport properties for LiD-U mixtures were calculated using a pressure matching mixture rule for the mixing of LiD and of U properties simulated with Orbital Free Molecular Dynamics (OFMD). The mixing rule was checked against benchmark OFMD simulations for the fully interacting three-component (Li, D, U) system. To obtain transport coefficients for LiD-U mixtures of different (LiD){sub x}U{sub (1-x)} compositions as functions of temperature and mixture density is a tedious task. Quantum molecular dynamics (MD) simulations can be employed, as in the case LiD or U. However, due to the presence of the heavy constituent U, such simulations proceed so slowly that only a limited number of numerical data points in the (x, {rho}, T) phase space can be obtained. To finesse this difficulty, transport coefficients for a mixture can be obtained using a pressure-matching mixing rule discussed. For both LiD and U, the corresponding transport coefficients were obtained earlier from quantum molecular dynamics simulations. In these simulations, the quantum behavior of the electrons was represented using an orbital free (OF) version of density functional theory, and ions were advanced in time using classical molecular dynamics. The total pressure of the system, P = nk{sub B}T/V + P{sub e}, is the sum of the ideal gas pressure of the ions plus the electron pressure. The mass self-diffusion coefficient for species {alpha}, D{sub {alpha}}, the mutual diffusion coefficient for species {alpha} and {beta}, D{alpha}{beta}, and the shear viscosity, {eta}, are computed from the appropriate autocorrelation function. The details of similar QMD calculations on LiH are described in Ref. [1] for 0.5 eV < T < 3 eV, and in Ref. [2] for 2 eV < T < 6 eV.

Burakovsky, Leonid [Los Alamos National Laboratory; Kress, Joel D. [Los Alamos National Laboratory; Collins, Lee A. [Los Alamos National Laboratory

2012-05-31

200

On the accuracy limits of orbital expansion methods: Explicit effects of k-functions on atomic and molecular energies  

E-print Network

On the accuracy limits of orbital expansion methods: Explicit effects of k-functions on atomic species to probe the accuracy limits of the conventional MP2 method vis-a`-vis explicitly correlated MP2-R of subchemical accuracy (0.1 kcal mol 1 ). © 2003 American Institute of Physics. DOI: 10.1063/1.1566744 I

Sherrill, David

201

Nickel(II) in chelate N2O2 environment. DFT approach and in-depth molecular orbital and configurational analysis.  

PubMed

The O-N-N-O-type tetradentate ligands H2S,S-eddp (H2S,S-eddp stands for S,S-ethylenediamine-N,N'-di-2-propionic acid) and H2edap (H2edap stands for ethylenediamine-N-acetic-N'-3-propionic acid) and the corresponding novel octahedral nickel(II) complexes have been prepared and characterized. N2O2 ligands coordinate to the nickel(II) ion via four donor atoms (two deprotonated carboxylate atoms and two amine nitrogens) affording octahedral geometry in the case of all investigated Ni(II) complexes. A six coordinate, octahedral geometry has been verified crystallographically for the s-cis-[Ni(S,S-eddp)(H2O)2] complex. Structural data correlating similarly chelated Ni(II) complexes have been used to carry out an extensive configuration analysis. Molecular mechanics and Density Functional Theory (DFT) have been used to model the most stable geometric isomer, yielding, at the same time, significant structural and spectroscopic (TDDFT) data. The results from density functional studies have been compared to X-ray data. Natural Bond Orbital (NBO) and Natural Energetic Decomposition Analysis (NEDA) have been done for the [Ni(edda-type)(H2O)(2-n)] and nH2O fragments. Molecular orbital analysis (MPA) is given as well. The infra-red and electronic absorption spectra of the complexes are discussed in comparison to the related complexes of known geometries. PMID:23884426

Trifunovi?, Sre?ko R; Mileti?, Vesna D; Jevti?, Verica V; Meetsma, Auke; Matovi?, Zoran D

2013-10-01

202

Untangling Euler Diagrams  

Microsoft Academic Search

In many common data analysis scenarios the data elements are logically grouped into sets. Venn and Euler style diagrams are a common visual representation of such set membership where the data elements are represented by labels or glyphs and sets are indicated by boundaries surrounding their members. Generating such diagrams automatically such that set regions do not intersect unless the

Nathalie Henry Riche; Tim Dwyer

2010-01-01

203

Algorithmic phase diagrams  

NASA Technical Reports Server (NTRS)

Algorithmic phase diagrams are a neat and compact representation of the results of comparing the execution time of several algorithms for the solution of the same problem. As an example, the recent results are shown of Gannon and Van Rosendale on the solution of multiple tridiagonal systems of equations in the form of such diagrams. The act of preparing these diagrams has revealed an unexpectedly complex relationship between the best algorithm and the number and size of the tridiagonal systems, which was not evident from the algebraic formulae in the original paper. Even so, for a particular computer, one diagram suffices to predict the best algorithm for all problems that are likely to be encountered the prediction being read directly from the diagram without complex calculation.

Hockney, Roger

1987-01-01

204

How to Interpret Circuit Diagrams  

NSDL National Science Digital Library

This site presents an explanation of how to interpret circuit diagrams. Two diagrams show the difference between a "short hand" circuit diagram and a more detailed one. The detailed circuit diagram is useful for those first learning circuits in an effort to eventually understand the "short hand" diagram without difficulty.

Lesurf, Jim

205

Vibrational spectra (FT-IR, FT-Raman), frontier molecular orbital, first hyperpolarizability, NBO analysis and thermodynamics properties of Piroxicam by HF and DFT methods.  

PubMed

The solid phase FT-IR and FT-Raman spectra of 4-Hydroxy-2-methyl-N-(2-pyridinyl)-2H-1,2-benzothiazine-3-carboxamide-1,1-dioxide (Piroxicam) have been recorded in the region 4000-400 and 4000-100cm(-1) respectively. The molecular geometry, harmonic vibrational frequencies and bonding features of piroxicam in the ground state have been calculated by Hartree-Fock (HF) and density functional theory (DFT) methods using 6-311++G(d,p) basis set. The calculated harmonic vibrational frequencies are scaled and they are compared with experimental obtained by FT-IR and FT-Raman spectra. A detailed interpretation of the vibrational spectra of the title compound has been made on the basis of the calculated potential energy distribution (PED). The electronic properties, such as HOMO and LUMO energies, molecular electrostatic potential (MESP) are also performed. The linear polarizability (?) and the first order hyper polarizability (?) values of the title compound have been computed. The molecular stability arising from hyper conjugative interaction, charge delocalization has been analyzed using natural bond orbital (NBO) analysis. PMID:25523048

Suresh, S; Gunasekaran, S; Srinivasan, S

2015-03-01

206

Molecular orbital (SCF-X??-SW) theory of Fe2+-Mn3+, Fe 3+-Mn 2+, and Fe3+-Mn3+ charge transfer and magnetic exchange in oxides and silicates  

USGS Publications Warehouse

Metal-metal charge-transfer and magnetic exchange interactions have important effects on the optical spectra, crystal chemistry, and physics of minerals. Previous molecular orbital calculations have provided insight on the nature of Fe2+-Fe3+ and Fe2+-Ti4+ charge-transfer transitions in oxides and silicates. In this work, spin-unrestricted molecular orbital calculations on (FeMnO10) clusters are used to study the nature of magnetic exchange and electron delocalization (charge transfer) associated with Fe3+-Mn2+, Fe3+-Mn3+, and Fe2+-Mn3+ interactions in oxides and silicates. -from Author

Sherman, D.M.

1990-01-01

207

Diagram of Computer Keyboard  

NSDL National Science Digital Library

This is a line drawing of a Windows PC keyboard complete with labels for each key. This diagram is used on tests where students are asked to circle the keys that would be used to perform various functions.

Ward, Charles

2011-01-21

208

Pioneer Venus orbiter  

NASA Technical Reports Server (NTRS)

The orbiter mission of the Pioneer Venus probe is discussed. In accordance with the low-cost Pioneer Venus concept, NASA intends to use the same basic spacecraft, known as the bus, for the execution of the two missions. The bus will be equipped with all of the subsystems common to the probe and orbiter missions (for example, thermal control, solar cells and power supply, attitude measurement and control, telemetry and communication electronics, and auxiliary propulsion unit). For the 1977 mission, the bus will be equipped with the large and small probes and a special antenna system. For the orbiter mission, the bus will be equipped with a retro-propulsion motor and a high-gain antenna. A diagram of the system envisaged is shown.

1974-01-01

209

Fragment molecular orbital calculations reveal that the E200K mutation markedly alters local structural stability in the human prion protein  

PubMed Central

The E200K mutation of the human prion protein (PrP) is known to cause familial Creutzfeldt-Jakob disease. In order to elucidate the effects of the mutation on the local structural stability of PrP, we performed ab initio fragment molecular orbital calculations for the wild-type human PrP and the E200K variant modeled under neutral and mild acidic conditions. The calculations revealed that this substitution markedly altered the intramolecular interactions in the PrP, suggesting that the local structural instabilities induced by the E200K mutation might cause initial denaturation of the PrP and its subsequent conversion to a pathogenic form. This work presents a new approach for quantitatively elucidating structural instabilities in proteins that cause misfolding diseases. PMID:20139714

Mohri, Shirou

2010-01-01

210

Analysis of solute-solvent interactions in the fragment molecular orbital method interfaced with effective fragment potentials: theory and application to a solvated griffithsin-carbohydrate complex.  

PubMed

Based on the proposed new expression of the polarization energy for the fragment molecular orbital (FMO) method interfaced with effective fragment potentials (EFPs), we develop an analysis of the solute(FMO)-solvent(EFP) interactions by defining individual fragment contributions for both solute and solvent. The obtained components are compared to all-electron calculations where water is treated as FMO fragments in the pair interaction energy decomposition analysis. The new energy expression is shown to be accurate, and the developed energy analysis is applied to the solvated griffithsin-carbohydrate complex. The details of the ligand recognition are revealed in the context with their interplay with the solvent effects. Tyr residue fragments are shown to reduce the desolvation penalty for Asp, which strongly binds the ligand. PMID:22894829

Nagata, Takeshi; Fedorov, Dmitri G; Sawada, Toshihiko; Kitaura, Kazuo

2012-09-13

211

Using simple molecular orbital calculations to predict disease: fast DFT methods applied to enzymes implicated in PKU, Parkinson's disease and Obsessive Compulsive Disorder  

NASA Astrophysics Data System (ADS)

Many diseases can be traced to point mutations in the DNA coding for specific enzymes. These point mutations result in the change of one amino acid residue in the enzyme. We have developed a model using simple molecular orbital calculations which can be used to quantitatively determine the change in interaction between the enzyme's active site and necessary ligands upon mutation. We have applied this model to three hydroxylase proteins: phenylalanine hydroxylase, tyrosine hydroxylase, and tryptophan hydroxylase, and we have obtained excellent correlation between our results and observed disease symptoms. Furthermore, we are able to use this agreement as a baseline to screen other mutations which may also cause onset of disease symptoms. Our focus is on systems where the binding is due largely to dispersion, which is much more difficult to model inexpensively than pure electrostatic interactions. Our calculations are run in parallel on a sixteen processor cluster of 64-bit Athlon processors.

Hofto, Laura; Hofto, Meghan; Cross, Jessica; Cafiero, Mauricio

2007-09-01

212

Vibrational spectra, molecular structure, natural bond orbital, first order hyperpolarizability, thermodynamic analysis and normal coordinate analysis of Salicylaldehyde p-methylphenylthiosemicarbazone by density functional method  

NASA Astrophysics Data System (ADS)

The thiosemicarbazone compound, Salicylaldehyde p-methylphenylthiosemicarbazone (abbreviated as SMPTSC) was synthesized and characterized by FTIR, FT-Raman and UV. Density functional (DFT) calculations have been carried out for the title compound by performing DFT level of theory using B3LYP/6-31++G(d,p) basis set. The molecular geometry and vibrational frequencies were calculated and compared with the experimental data. The detailed interpretation of the vibrational spectra has been carried out with aid of normal coordinate analysis (NCA) following the scaled quantum mechanical force field methodology. The electronic dipole moment (?D) and the first hyperpolarizability (?tot) values of the investigated molecule were computed using density functional theory (DFT/B3LYP) with 6-311++G(d,p) basis set. The stability and charge delocalization of the molecule was studied by natural bond orbital (NBO) analysis. Thearomaticities of the phenyl rings were studied using the standard harmonic oscillator model of aromaticity (HOMA) index. Mulliken population analysis on atomic charges is also calculated. The molecule orbital contributions are studied by density of energy states (DOSs).

Porchelvi, E. Elamurugu; Muthu, S.

2015-01-01

213

Molecular structure, Normal Coordinate Analysis, harmonic vibrational frequencies, Natural Bond Orbital, TD-DFT calculations and biological activity analysis of antioxidant drug 7-hydroxycoumarin  

NASA Astrophysics Data System (ADS)

In this work, we report harmonic vibrational frequencies, molecular structure, NBO and HOMO, LUMO analysis of Umbelliferone also known as 7-hydroxycoumarin (7HC). The optimized geometric bond lengths and bond angles obtained by computation (monomer and dimmer) shows good agreement with experimental XRD data. Harmonic frequencies of 7HC were determined and analyzed by DFT utilizing 6-311+G(d,p) as basis set. The assignments of the vibrational spectra have been carried out with the help of Normal Coordinate Analysis (NCA) following the Scaled Quantum Mechanical Force Field Methodology (SQMFF). The change in electron density (ED) in the ?* and ?* antibonding orbitals and stabilization energies E(2) have been calculated by Natural Bond Orbital (NBO) analysis to give clear evidence of stabilization originating in the hyperconjugation of hydrogen-bonded interaction. The energy and oscillator strength calculated by Time-Dependent Density Functional Theory (TD-DFT) complements with the experimental findings. The simulated spectra satisfactorily coincides with the experimental spectra. Microbial activity of studied compounds was tested against Staphylococcus aureus, Streptococcus pyogenes, Bacillus subtilis, Escherichia coli, Psuedomonas aeruginosa, Klebsiella pneumoniae, Proteus mirabilis, Shigella flexneri, Salmonella typhi and Enterococcus faecalis.

Sebastian, S.; Sylvestre, S.; Jayarajan, D.; Amalanathan, M.; Oudayakumar, K.; Gnanapoongothai, T.; Jayavarthanan, T.

2013-01-01

214

Molecular structure, Normal Coordinate Analysis, harmonic vibrational frequencies, Natural Bond Orbital, TD-DFT calculations and biological activity analysis of antioxidant drug 7-hydroxycoumarin.  

PubMed

In this work, we report harmonic vibrational frequencies, molecular structure, NBO and HOMO, LUMO analysis of Umbelliferone also known as 7-hydroxycoumarin (7HC). The optimized geometric bond lengths and bond angles obtained by computation (monomer and dimmer) shows good agreement with experimental XRD data. Harmonic frequencies of 7HC were determined and analyzed by DFT utilizing 6-311+G(d,p) as basis set. The assignments of the vibrational spectra have been carried out with the help of Normal Coordinate Analysis (NCA) following the Scaled Quantum Mechanical Force Field Methodology (SQMFF). The change in electron density (ED) in the ?* and ?* antibonding orbitals and stabilization energies E(2) have been calculated by Natural Bond Orbital (NBO) analysis to give clear evidence of stabilization originating in the hyperconjugation of hydrogen-bonded interaction. The energy and oscillator strength calculated by Time-Dependent Density Functional Theory (TD-DFT) complements with the experimental findings. The simulated spectra satisfactorily coincides with the experimental spectra. Microbial activity of studied compounds was tested against Staphylococcus aureus, Streptococcus pyogenes, Bacillus subtilis, Escherichia coli, Psuedomonas aeruginosa, Klebsiella pneumoniae, Proteus mirabilis, Shigella flexneri, Salmonella typhi and Enterococcus faecalis. PMID:23123244

Sebastian, S; Sylvestre, S; Jayarajan, D; Amalanathan, M; Oudayakumar, K; Gnanapoongothai, T; Jayavarthanan, T

2013-01-15

215

Weyl Card Diagrams  

E-print Network

To capture important physical properties of a spacetime we construct a new diagram, the card diagram, which accurately draws generalized Weyl spacetimes in arbitrary dimensions by encoding their global spacetime structure, singularities, horizons, and some aspects of causal structure including null infinity. Card diagrams draw only non-trivial directions providing a clearer picture of the geometric features of spacetimes as compared to Penrose diagrams, and can change continuously as a function of the geometric parameters. One of our main results is to describe how Weyl rods are traversable horizons and the entirety of the spacetime can be mapped out. We review Weyl techniques and as examples we systematically discuss properties of a variety of solutions including Kerr-Newman black holes, black rings, expanding bubbles, and recent spacelike-brane solutions. Families of solutions will share qualitatively similar cards. In addition we show how card diagrams not only capture information about a geometry but also its analytic continuations by providing a geometric picture of analytic continuation. Weyl techniques are generalized to higher dimensional charged solutions and applied to generate perturbations of bubble and S-brane solutions by Israel-Khan rods. This paper is a condensed and simplified presentation of the card diagrams in hep-th/0409070.

Gregory C. Jones; John E. Wang

2005-06-02

216

Gradient of molecular Hartree–Fock–Bogoliubov energy with a linear combination of atomic orbital quasiparticle wave functions  

SciTech Connect

The analytical gradient for the atomic-orbital-based Hartree–Fock–Bogoliubov (HFB) energy functional, the modified form of which was proposed by Staroverov and Scuseria to account for the static electron correlation [J. Chem. Phys. 117, 11107 (2002)], is derived. Interestingly, the Pulay force for the HFB energy is expressed with the same formula as that for the Hartree–Fock method. The efficiency of the present HFB energy gradient is demonstrated in the geometry optimizations of conjugated and biradical systems. The geometries optimized by using the HFB method with the appropriate factor ?, which controls the degree of static correlation included, are found to show good agreement with those obtained by using a complete active-space self-consistent field method, although they are significantly dependent on ?.

Kobayashi, Masato, E-mail: kobayashi@suou.waseda.jp [Waseda Institute for Advanced Study, Waseda University, Tokyo 169-8050 (Japan)] [Waseda Institute for Advanced Study, Waseda University, Tokyo 169-8050 (Japan)

2014-02-28

217

Quantitative Structure-Toxicity Relationships for Halobenzenes in Two Species of Bioluminescent Bacteria, Pseudomonas fluorescens and Vibrio fischeri, Using an Atom-Centered SemiEmpirical Molecular-Orbital Based Model  

Microsoft Academic Search

Literature data on the toxicity of substituted benzenes for two bioluminescent bacteria, Pseudomonas fluorescens and Vibrio fischeri have been compared and analysed in relation to a set of computed molecular physico–chemical properties using a quantitative structure-activity approach. The quantitative structure-toxicity relationships of the compounds in each species showed marked differences when based upon semi-empirical molecular-orbital whole molecule and atom based

M. A. Warne; E. M. Boyd; A. A. Meharg; D. Osborn; K. Killham; J. C. Lindon; J. K. Nicholson

1999-01-01

218

On-Orbit Propulsion OMS/RCS  

NASA Technical Reports Server (NTRS)

This slide presentation reviews the Space Shuttle's On-Orbit Propulsion systems: the Orbital Maneuvering System (OMS) and the Reaction Control System (RCS). The functions of each of the systems is described, and the diagrams of the systems are presented. The OMS/RCS thruster is detailed and a trade study comparison of non-toxic propellants is presented.

Hurlbert, Eric A.

2001-01-01

219

Development of a Silicon Carbide Molecular Beam Nozzle for Simulation Planetary Flybys and Low-Earth Orbit  

NASA Technical Reports Server (NTRS)

From commercial origins as a molybdenum molecular beam nozzle, a ceramic nozzle of silicon carbide (SiC) was developed for space environment simulation. The nozzle is mechanically stable under extreme conditions of temperature and pressure. A heated, continuous, supersonically-expanded hydrogen beam with a 1% argon seed produced an argon beam component of nearly 4 km/s, with an argon flux exceeding 1x1014 /cm2.s. This nozzle was part of a molecular beam machine used in the Atmospheric Experiments Branch at NASA Goddard Space Flight Center to characterize the performance of the University of Texas at Dallas Ram Wind Sensor (RWS) aboard the Air Force Communications/Navigation Outage Forecasting System (C/NOFS) launched in the Spring of 2008.

Patrick, E. L.; Earle, G. D.; Kasprzak, W. T.; Mahaffy, Paul R.

2008-01-01

220

Weyl card diagrams  

SciTech Connect

To capture important physical properties of a spacetime we construct a new diagram, the card diagram, which accurately draws generalized Weyl spacetimes in arbitrary dimensions by encoding their global spacetime structure, singularities, horizons, and some aspects of causal structure including null infinity. Card diagrams draw only nontrivial directions providing a clearer picture of the geometric features of spacetimes as compared to Penrose diagrams, and can change continuously as a function of the geometric parameters. One of our main results is to describe how Weyl rods are traversable horizons and the entirety of the spacetime can be mapped out. We review Weyl techniques and as examples we systematically discuss properties of a variety of solutions including Kerr-Newman black holes, black rings, expanding bubbles, and recent spacelike-brane solutions. Families of solutions will share qualitatively similar cards. In addition we show how card diagrams not only capture information about a geometry but also its analytic continuations by providing a geometric picture of analytic continuation. Weyl techniques are generalized to higher dimensional charged solutions and applied to generate perturbations of bubble and S-brane solutions by Israel-Khan rods.

Jones, Gregory [Department of Physics, Harvard University, Cambridge, Massachusetts 02138 (United States); Wang, John E. [Department of Physics, Harvard University, Cambridge, Massachusetts 02138 (United States); Department of Physics, National Taiwan University, Taipei 106, Taiwan (China); National Center for Theoretical Sciences, Taiwan, National Taiwan University, Taipei 10617, Taiwan (China)

2005-06-15

221

Minkowski Diagram Model  

NSDL National Science Digital Library

The Minkowski Diagram model displays the spacetime diagrams for two inertial observers. One or two events may be displayed and moved with the mouse. Optionally, the corresponding light cones may be shown, as well as the simultaneity lines in both reference frames. The spacetime interval is automatically computed. The simulation may be used to discuss simultaneity and causality in special relativity. You can modify this simulation if you have Ejs installed by right-clicking within the plot and selecting "Open Ejs Model" from the pop-up menu item. The Minkowski Diagram model was created using the Easy Java Simulations (Ejs) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_ehu_special_relativity_minkowski.jar file will run the program if Java is installed. Please note that this resource requires at least version 1.5 of Java (JRE).

Aguirregabiria, Juan

2011-09-09

222

Diblock copolymer phase diagram  

NSDL National Science Digital Library

Adaptation of the Matsen and Bates BCP phase diagram predicted using Mean-field Theory. * Matsen MW, Bates FS, ''http://pubs3.acs.org/acs/journals/doilookup?in_doi=10.1021/ma951138i Unifying weak- and strong-segregation block copolymer theories. Diblock copolymer phase diagram as calculated using Mean-field Theory by Matsen and Bates, where fA is the Block fraction, Ï is the Flory-Huggins Chi Parameter, and N is the length of the block.

Iacovella, Christopher R.

2006-11-20

223

Homoclinic bifurcation properties near eight-gure homoclinic orbit  

E-print Network

Homoclinic bifurcation properties near eight-#12;gure homoclinic orbit Yong-Kui Zou #3; Department investigate the homoclinic bifurcation properties near a co-dimension two eight-#12;gure homoclinic orbit computation. Keywords: Eight #12;gure homoclinic orbit, bifurcation diagram. AMS Classi#12;cation: Primary 65L

Bielefeld, Universität

224

Carbon Cycle Diagram  

NSDL National Science Digital Library

This diagram illustrates some of the most abundant stores of carbon and identifies some of the pathways in the carbon cycle along which carbon is transferred from one form to another. Long-term sinks of carbon are labelled in black; shorter-term fluxes are labelled in purple. Amounts are in billions of tons.

225

Reading Diagrams. Pipefitter.  

ERIC Educational Resources Information Center

Developed by the ABCs of Construction National Workplace Literacy Project, these curriculum materials for the occupational area of pipefitting contain a lesson that deals with reading diagrams. The lesson consists of an objective, instruction, and 10 exercises. Three types of problems are provided in each exercise: "try it,""apply it," and "go…

Greater Baton Rouge Chamber of Commerce, LA.

226

Venn Diagrams and Logic  

NSDL National Science Digital Library

This math lesson from Illuminations uses Venn diagrams to illustrate direct, indirect and transitive reasoning. Students will learn the definitions of direct, indirect and transitive reasoning and give examples of each. Several student activity sheets are included. The material is intended for grades 9-12 and should require 2 and a half class periods to complete.

2011-01-04

227

Impulse-Momentum Diagrams  

ERIC Educational Resources Information Center

Multiple representations are a valuable tool to help students learn and understand physics concepts. Furthermore, representations help students learn how to think and act like real scientists. These representations include: pictures, free-body diagrams, energy bar charts, electrical circuits, and, more recently, computer simulations and…

Rosengrant, David

2011-01-01

228

Simultaneity Spacetime Diagram Model  

NSDL National Science Digital Library

The Simultaneity Spacetime Diagram model uses light-trajectories to show the effect of relative motion when observing (recording) events in special relativity. In the default scenario, an explosion (an event) at the center of a right-moving stick occurs at t=0 and the arrival of the explosion light signal at each end is recorded. The arrival event at the left end occurs before the arrival event at the right end because the stick is moving. How do the location and time of these events change if they are observed in a reference frame (the Other Frame) in which the stick is stationary?   The Simultaneity Spacetime Diagram model was written for the study of special relativity the Lorentz transformation using spacetime diagrams and is a supplemental simulation for an article by Sebastien Cromier and Richard Steinberg "The Twin Twin Paradox: Exploring Student Approaches to Understanding Relativistic Concepts" in the The Physics Teacher 48 (9), 598-601 (2010). Initial conditions, such as the locations of the explosion and the detectors, can be adjusted by dragging before the simulation is run. The slider can be used to change the speed of the stick. A third view shows the stick and the wavefront in space. More importantly, a checkbox allows users to compare the predictions of Galilean and special relativity in order to observe how the assumption of a constant speed of light leads to the relativity of simultaneity.   The Simultaneity Spacetime Diagram model was created using the Easy Java Simulations (EJS) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_sr_SimultaneitySpacetimeDiagram.jar file will run the program if Java is installed.

Christian, Wolfgang

2010-10-07

229

Yukawa Monte Carlo (YMC) and Orbital Free Molecular Dynamics (OFMD) approaches for the eos of warm dense iron plasma  

NASA Astrophysics Data System (ADS)

Yukawa Monte Carlo and Molecular Dynamics simulations are powerful techniques extensively used to compute plasma properties such as EOS or transport coefficients, but are limited to applications where the linear electronic screening assumption is valid (1). Recently we have shown that a modified scheme using density functional theory with a Thomas-Fermi kinetic energy functional for the electrons (OFMD) may be well suited to perform MD simulations at high densities and temperature, without any assumption on the electronic screening (2). For selected iron plasma conditions representative of warm and dense matter, we shall compare pressure results calculated using YMC and OFMD codes and QEOS (3) and Sesame EOS models (4) and discuss the influence of keys parameters, like ionization in Yukawa theory. References: [1] D. Gilles, O. Peyrusse, JQSRT 53, 6, 1995. ;Caillol J-M, Gilles D., J. Stat Phys. 100, N5/6, 905-947, 2000; Caillol J-M, Gilles D., J. Phys. A 36, 6243, (2003) ; A. Potekhin, G. Chabrier, Gilles, PRE 65, 036412, 2002. [2] D. Gilles, F. Lambert, J. Cl'erouin, S. Mazevet, Gwena"el Salin, HEDP 3, 95-98, 2007; F. Lambert, J. Cl'erouin, S. Mazevet, D. Gilles, Plama Physics, 47,4-5, 272-280(2007). [3] R.M. More, Lawrence Livermore Laboratory Report, UCRL-84991, (1981). [4] G.I. Kerley, User's Manual for PANDA : A computer Code for calculating Equation of State, Los Alamos National Laboratory, 1981 (LA8833).

Gilles, Dominique; Lambert, Flavien; Clerouin, Jean

2008-04-01

230

Structure investigation of three hydrazones Schiff's bases by spectroscopic, thermal and molecular orbital calculations and their biological activities.  

PubMed

Three Schiff's bases AI (2(1-hydrazonoethyl)phenol), AII (2, 4-dibromo 6-(hydrazonomethyl)phenol) and AIII (2(hydrazonomethyl)phenol) were prepared as new hydrazone compounds via condensation reactions with molar ratio (1:1) of reactants. Firstly by reaction of 2-hydroxy acetophenone solution and hydrazine hydrate; it gives AI. Secondly condensation between 3,5-dibromo-salicylaldehyde and hydrazine hydrate gives AII. Thirdly condensation between salicylaldehyde and hydrazine hydrate gives AIII. The structures of AI-AIII were characterized by elemental analysis (EA), mass (MS), FT-IR and (1)H NMR spectra, and thermal analyses (TG, DTG, and DTA). The activation thermodynamic parameters, such as, ?E(?), ?H(?), ?S(?) and ?G(?) were calculated from the TG curves using Coats-Redfern method. It is important to investigate their molecular structures to know the active groups and weak bond responsible for their biological activities. Consequently in the present work, the obtained thermal (TA) and mass (MS) practical results are confirmed by semi-empirical MO-calculations (MOCS) using PM3 procedure. Their biological activities have been tested in vitro against Escherichia coli, Proteus vulgaris, Bacillissubtilies and Staphylococcus aurous bacteria in order to assess their anti-microbial potential. PMID:25437844

Belal, Arafa A M; Zayed, M A; El-Desawy, M; Rakha, Sh M A H

2015-03-01

231

Ab initio molecular dynamics: Propagating the density matrix with Gaussian orbitals. III. Comparison with Born-Oppenheimer dynamics  

NASA Astrophysics Data System (ADS)

In a recently developed approach to ab initio molecular dynamics (ADMP), we used an extended Lagrangian to propagate the density matrix in a basis of atom centered Gaussian functions. Results of trajectory calculations obtained by this method are compared with the Born-Oppenheimer approach (BO), in which the density is converged at each step rather than propagated. For NaCl, the vibrational frequency with ADMP is found to be independent of the fictitious electronic mass and to be equal to the BO trajectory result. For the photodissociation of formaldehyde, H2CO[right arrow]H2+CO, and the three body dissociation of glyoxal, C2H2O2[right arrow]H2+2CO, very good agreement is found between the Born-Oppenheimer trajectories and the extended Lagrangian approach in terms of the rotational and vibrational energy distributions of the products. A 1.2 ps simulation of the dynamics of chloride ion in a cluster of 25 water molecules was used as a third test case. The Fourier transform of the velocity-velocity autocorrelation function showed the expected features in the vibrational spectrum corresponding to strong hydrogen bonding in the cluster. A redshift of approximately 200 cm-1 was observed in the hydroxyl stretch due to the presence of the chloride ion. Energy conservation and adiabaticity were maintained very well in all of the test cases.

Schlegel, H. Bernhard; Iyengar, Srinivasan S.; Li, Xiaosong; Millam, John M.; Voth, Gregory A.; Scuseria, Gustavo E.; Frisch, Michael J.

2002-11-01

232

Structure investigation of three hydrazones Schiff's bases by spectroscopic, thermal and molecular orbital calculations and their biological activities  

NASA Astrophysics Data System (ADS)

Three Schiff's bases AI (2(1-hydrazonoethyl)phenol), AII (2, 4-dibromo 6-(hydrazonomethyl)phenol) and AIII (2(hydrazonomethyl)phenol) were prepared as new hydrazone compounds via condensation reactions with molar ratio (1:1) of reactants. Firstly by reaction of 2-hydroxy acetophenone solution and hydrazine hydrate; it gives AI. Secondly condensation between 3,5-dibromo-salicylaldehyde and hydrazine hydrate gives AII. Thirdly condensation between salicylaldehyde and hydrazine hydrate gives AIII. The structures of AI-AIII were characterized by elemental analysis (EA), mass (MS), FT-IR and 1H NMR spectra, and thermal analyses (TG, DTG, and DTA). The activation thermodynamic parameters, such as, ?E?, ?H?, ?S? and ?G? were calculated from the TG curves using Coats-Redfern method. It is important to investigate their molecular structures to know the active groups and weak bond responsible for their biological activities. Consequently in the present work, the obtained thermal (TA) and mass (MS) practical results are confirmed by semi-empirical MO-calculations (MOCS) using PM3 procedure. Their biological activities have been tested in vitro against Escherichia coli, Proteus vulgaris, Bacillissubtilies and Staphylococcus aurous bacteria in order to assess their anti-microbial potential.

Belal, Arafa A. M.; Zayed, M. A.; El-Desawy, M.; Rakha, Sh. M. A. H.

2015-03-01

233

Localized orbital corrections applied to thermochemical errors in density functional theory: The role of basis set and application to molecular reactions  

PubMed Central

This paper is a logical continuation of the 22 parameter, localized orbital correction (LOC) methodology that we developed in previous papers [R. A. Friesner , 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. PMID:19063542

Goldfeld, Dahlia A.; Bochevarov, Arteum D.; Friesner, Richard A.

2008-01-01

234

Quantum mechanical calculations and spectroscopic (FT-IR, FT-Raman and UV) investigations, molecular orbital, NLO, NBO, NLMO and MESP analysis of 4-[5-(4-methylphenyl)-3-(trifluoromethyl)-1H-pyrazol-1-yl] benzene-1-sulfonamide  

NASA Astrophysics Data System (ADS)

The molecular structural parameters and vibrational frequencies of the fundamental modes of 4-[5-(4-methylphenyl)-3-(trifluoromethyl)-1H-pyrazol-1-yl] benzene-1-sulfonamide(abbreviated as 4MPTFM1HPB1SA) have been obtained using Density functional theory (DFT) technique in the B3LYP approximation with 6-311G(d,p) and 6-311++G(d,p) basis sets. Detailed vibrational assignments of the observed FT-IR and FT-Raman bands have been proposed on the basis of potential energy distribution (PED). The difference between the observed and the calculated wavenumbers values are very small. The theoretically predicted FT-IR and FT-Raman spectra of the title molecule have been constructed. The molecular electrostatic potential has been mapped primarily for predicting sites and relative reactivities toward electrophilic and nucleophilic attack. The intramolecular contacts have been interpreted using Natural Bond Orbital (NBO) and Natural Localized Molecular Orbital (NLMO) analysis. Important non-linear properties such as electric dipolemoment and first hyperpolarizability of 4MPTFM1HPB1SA have been computed using B3LYP quantum chemical calculation. The absorption wavelength, energy and oscillator's strength are calculated by TD-DFT and 4MPTFM1HPB1SA is approach complement with the experimental findings. The temperature dependence of thermodynamic properties has been analyzed. The Natural charges, Frontier molecular orbitals (FMOs), chemical hardness (?), chemical potential (?), Electro negativity (?) and electrophilicity values (?) are calculated and reported.

Govindasamy, P.; Gunasekaran, S.

2015-02-01

235

A combined effective fragment potential-fragment molecular orbital method. II. Analytic gradient and application to the geometry optimization of solvated tetraglycine and chignolin.  

PubMed

The gradient for the fragment molecular orbital (FMO) method interfaced with effective fragment potentials (EFP), denoted by FMO?EFP, was developed and applied to polypeptides solvated in water. The structures of neutral and zwitterionic tetraglycine immersed in water layers of 2.0, 2.5, 3.0, 3.5, 4.0, and 4.5 A? are investigated by performing FMO?EFP geometry optimizations at the RHF?cc-pVDZ level of theory for the solutes. The geometries optimized with FMO-RHF?EFP are compared to those from the conventional RHF?EFP and are found to be in very close agreement. Using the optimized geometries, the stability of the hydrated zwitterionic and neutral structures is discussed structurally and in terms of energetics at the second-order Møller-Plesset theory (MP2)?cc-pVDZ level. To demonstrate the potential of the method for proteins, the geometry of hydrated chignolin (protein data bank ID: 1UAO) was optimized, and the importance of the inclusion of water was examined by comparing the solvated and gas phase structures of chignolin with the experimental NMR structure. PMID:21261333

Nagata, Takeshi; Fedorov, Dmitri G; Sawada, Toshihiko; Kitaura, Kazuo; Gordon, Mark S

2011-01-21

236

Structure, electronic and magnetic properties of hexagonal boron nitride sheets doped by 5d transition metal atoms: First-principles calculations and molecular orbital analysis  

NASA Astrophysics Data System (ADS)

A first-principles calculation based on density functional theory is carried out to reveal the geometry, electronic structures and magnetic properties of hexagonal boron nitride sheets (h-BNSs) doped by 5d transitional mental atoms (Lu, Hf, Ta, W, Re, Os, Ir, Pt, Au and Hg) at boron-site (B5d) and nitrogen-site (N5d). Results of pure h-BNS, h-BNS with B vacancy (VB) and N vacancy (VN) are also given for comparison. It is shown that all the h-BNSs doped with 5d atoms possess a C3v local symmetry except for NLu and NHg which have a clear deviation. For the same 5d dopant, the binding energy of B5d is larger than that of N5d, which indicates the substitution of a 5d atom for B is preferred. The total densities of states are presented, where impurity energy levels exist. Besides, the total magnetic moments (TMMs) change regularly with the increment of the 5d atomic number. Theoretical analyses by molecular orbital under C3v symmetry explain the impurity energy levels and TMMs.

Zhang, Zhaofu; Geng, Zhaohui; Cai, Danyun; Pan, Tongxi; Chen, Yixin; Dong, Liyuan; Zhou, Tiege

2015-01-01

237

A combined effective fragment potential-fragment molecular orbital method. II. Analytic gradient and application to the geometry optimization of solvated tetraglycine and chignolin  

NASA Astrophysics Data System (ADS)

The gradient for the fragment molecular orbital (FMO) method interfaced with effective fragment potentials (EFP), denoted by FMO/EFP, was developed and applied to polypeptides solvated in water. The structures of neutral and zwitterionic tetraglycine immersed in water layers of 2.0, 2.5, 3.0, 3.5, 4.0, and 4.5 Å are investigated by performing FMO/EFP geometry optimizations at the RHF/cc-pVDZ level of theory for the solutes. The geometries optimized with FMO-RHF/EFP are compared to those from the conventional RHF/EFP and are found to be in very close agreement. Using the optimized geometries, the stability of the hydrated zwitterionic and neutral structures is discussed structurally and in terms of energetics at the second-order Møller-Plesset theory (MP2)/cc-pVDZ level. To demonstrate the potential of the method for proteins, the geometry of hydrated chignolin (protein data bank ID: 1UAO) was optimized, and the importance of the inclusion of water was examined by comparing the solvated and gas phase structures of chignolin with the experimental NMR structure.

Nagata, Takeshi; Fedorov, Dmitri G.; Sawada, Toshihiko; Kitaura, Kazuo; Gordon, Mark S.

2011-01-01

238

Analytic gradient for second order Møller-Plesset perturbation theory with the polarizable continuum model based on the fragment molecular orbital method.  

PubMed

A new energy expression is proposed for the fragment molecular orbital method interfaced with the polarizable continuum model (FMO/PCM). The solvation free energy is shown to be more accurate on a set of representative polypeptides with neutral and charged residues, in comparison to the original formulation at the same level of the many-body expansion of the electrostatic potential determining the apparent surface charges. The analytic first derivative of the energy with respect to nuclear coordinates is formulated at the second-order Møller-Plesset (MP2) perturbation theory level combined with PCM, for which we derived coupled perturbed Hartree-Fock equations. The accuracy of the analytic gradient is demonstrated on test calculations in comparison to numeric gradient. Geometry optimization of the small Trp-cage protein (PDB: 1L2Y) is performed with FMO/PCM/6-31(+)G(d) at the MP2 and restricted Hartree-Fock with empirical dispersion (RHF/D). The root mean square deviations between the FMO optimized and NMR experimental structure are found to be 0.414 and 0.426 A? for RHF/D and MP2, respectively. The details of the hydrogen bond network in the Trp-cage protein are revealed. PMID:22667545

Nagata, Takeshi; Fedorov, Dmitri G; Li, Hui; Kitaura, Kazuo

2012-05-28

239

Quaternary ammonium room-temperature ionic liquid including an oxygen atom in side chain/lithium salt binary electrolytes: ab initio molecular orbital calculations of interactions between ions.  

PubMed

Interactions of the lithium bis(trifluoromethylsulfonyl)amide (LiTFSA) complex with N, N-diethyl-N-methyl-N-(2-methoxyethyl) ammonium (DEME), 1-ethyl-3-methylimidazolium (EMIM) cations, neutral diethylether (DEE), and the DEMETFSA complex were studied by ab initio molecular orbital calculations. An interaction energy potential calculated for the DEME cation with the LiTFSA complex has a minimum when the Li atom has contact with the oxygen atom of DEME cation, while potentials for the EMIM cation with the LiTFSA complex are always repulsive. The MP2/6-311G**//HF/6-311G** level interaction energy calculated for the DEME cation with the LiTFSA complex was -18.4 kcal/mol. The interaction energy for the neutral DEE with the LiTFSA complex was larger (-21.1 kcal/mol). The interaction energy for the DEMETFSA complex with LiTFSA complex is greater (-23.2 kcal/mol). The electrostatic and induction interactions are the major source of the attraction in the two systems. The substantial attraction between the DEME cation and the LiTFSA complex suggests that the interaction between the Li cation and the oxygen atom of DEME cation plays important roles in determining the mobility of the Li cation in DEME-based room temperature ionic liquids. PMID:18636771

Tsuzuki, Seiji; Hayamizu, Kikuko; Seki, Shiro; Ohno, Yasutaka; Kobayashi, Yo; Miyashiro, Hajime

2008-08-14

240

An Introduction to Tree Diagrams  

NSDL National Science Digital Library

This brief article describes the use of tree diagrams in calculating probabilities. The author provides examples of how tree diagrams are used to calculate specific probabilities and why the language chosen relates to the operations used to find the probability.

Cork, Stu

2014-01-01

241

Dynamical evolution of active detached binaries on the logJo-logM diagram and contact binary formation  

Microsoft Academic Search

Orbital angular momentum (OAM, Jo), systemic mass (M) and orbital period (P) distributions of chromospherically active binaries (CAB) and W Ursae Majoris (W UMa) systems were investigated. The diagrams of and logJo-logM were formed from 119 CAB and 102 W UMa stars. The logJo-logM diagram is found to be most meaningful in demonstrating dynamical evolution of binary star orbits. A

Z. Eker; O. Demircan; S. Bilir; Y. Karatas

2006-01-01

242

TEP process flow diagram  

SciTech Connect

This presentation describes the development of the proposed Process Flow Diagram (PFD) for the Tokamak Exhaust Processing System (TEP) of ITER. A brief review of design efforts leading up to the PFD is followed by a description of the hydrogen-like, air-like, and waterlike processes. Two new design values are described; the mostcommon and most-demanding design values. The proposed PFD is shown to meet specifications under the most-common and mostdemanding design values.

Wilms, R Scott [Los Alamos National Laboratory; Carlson, Bryan [Los Alamos National Laboratory; Coons, James [Los Alamos National Laboratory; Kubic, William [Los Alamos National Laboratory

2008-01-01

243

Untangling euler diagrams.  

PubMed

In many common data analysis scenarios the data elements are logically grouped into sets. Venn and Euler style diagrams are a common visual representation of such set membership where the data elements are represented by labels or glyphs and sets are indicated by boundaries surrounding their members. Generating such diagrams automatically such that set regions do not intersect unless the corresponding sets have a non-empty intersection is a difficult problem. Further, it may be impossible in some cases if regions are required to be continuous and convex. Several approaches exist to draw such set regions using more complex shapes, however, the resulting diagrams can be difficult to interpret. In this paper we present two novel approaches for simplifying a complex collection of intersecting sets into a strict hierarchy that can be more easily automatically arranged and drawn (Figure 1). In the first approach, we use compact rectangular shapes for drawing each set, attempting to improve the readability of the set intersections. In the second approach, we avoid drawing intersecting set regions by duplicating elements belonging to multiple sets. We compared both of our techniques to the traditional non-convex region technique using five readability tasks. Our results show that the compact rectangular shapes technique was often preferred by experimental subjects even though the use of duplications dramatically improves the accuracy and performance time for most of our tasks. In addition to general set representation our techniques are also applicable to visualization of networks with intersecting clusters of nodes. PMID:20975147

Riche, Nathalie Henry; Dwyer, Tim

2010-01-01

244

On web diagrams Jun Murakami  

E-print Network

On web diagrams Jun Murakami Department of Mathematics, Graduate School of Science, Osaka­ tive invariant is defined in the space of web diagrams, and it includes the Casson­ Walker invariant of the mapping class groups. (cf. [9], [10]) 2. Web space 2.1. Web diagram. To explain the universal perturbative

245

Molecular orbital (SCF-X??-SW) theory of metal-metal charge transfer processes in minerals - I. application to Fe2+???Fe3+ charge transfer and "electron delocalization" in mixed-valence iron oxides and silicates  

USGS Publications Warehouse

A number of mixed valence iron oxides and silicates (e.g., magnetite, ilvaite) exhibit thermally induced electron delocalization between adjacent Fe2+ and Fe3+ ions and optically induced electronic transitions which are assigned to Fe2+???Fe3+ intervalence charge transfer. In this paper, the mechanism of electron delocalization (i.e., polarons versus itinerant electrons) and the nature of optically induced intervalence charge-transfer in minerals are investigated using molecular orbital theory. SCF-X??-SW molecular orbital calculations were done for several mixed-valence (Fe2O10)15- clusters corresponding to edgesharing Fe2+ and Fe3+ coordination polyhedra. A spinunrestricted formalism was used so that the effect of ferromagnetic versus antiferromagnetic coupling of adjacent Fe2+ and Fe3+ cations could be determined. The molecular orbital results can be related to the polaron theory of solid state physics and the perturbation theory formalism used by Robin and Day (1967) and others to describe electron transfer in mixed valence compounds. Intervalence charge-transfer results from the overlap of Fe(3d) orbitals across the shared edges of adjacent FeO6 polyhedra to give weak Fe-Fe bonds. Electron delocalization, however, requires that adjacent Fe cations be ferromagnetically coupled. Antiferromagnetic coupling results in distinguishable Fe2+ and Fe3+ cations. Electronic transitions between the Fe-Fe bonding and Fe-Fe antibonding orbitals results in the optically-induced intervalence charge transfer bands observed in the electronic spectra of mixed valence minerals. Such transitions are predicted to be polarized along the metal-metal bond direction, in agreement with experimental observations. ?? 1987 Springer-Verlag.

Sherman, D.M.

1987-01-01

246

[Orbital inflammation].  

PubMed

Orbital inflammation is a generic term encompassing inflammatory pathologies affecting all structures within the orbit : anterior (involvement up to the posterior aspect of the globe), diffuse (involvement of intra- and/or extraconal fat), apical (involvement of the posterior orbit), myositis (involvement of only the extraocular muscles), dacryoadenitis (involvement of the lacrimal gland). We distinguish between specific inflammation and non-specific inflammation, commonly referred to as idiopathic inflammation. Specific orbital inflammation corresponds to a secondary localization of a "generalized" disease (systemic or auto-immune). Idiopathic orbital inflammation corresponds to uniquely orbital inflammation without generalized disease, and thus an unknown etiology. At the top of the differential diagnosis for specific or idiopathic orbital inflammation are malignant tumors, represented most commonly in the adult by lympho-proliferative syndromes and metastases. Treatment of specific orbital inflammation begins with treatment of the underlying disease. For idiopathic orbital inflammation, treatment (most often corticosteroids) is indicated above all in cases of visual loss due to optic neuropathy, in the presence of pain or oculomotor palsy. PMID:25455557

Mouriaux, F; Coffin-Pichonnet, S; Robert, P-Y; Abad, S; Martin-Silva, N

2014-12-01

247

Three- and four-body corrected fragment molecular orbital calculations with a novel subdividing fragmentation method applicable to structure-based drug design.  

PubMed

We develop an inter-fragment interaction energy (IFIE) analysis based on the three- and four-body corrected fragment molecular orbital (FMO3 and FMO4) method to evaluate the interactions of functional group units in structure-based drug design context. The novel subdividing fragmentation method for a ligand (in units of their functional groups) and amino acid residues (in units of their main and side chains) enables us to understand the ligand-binding mechanism in more detail without sacrificing chemical accuracy of the total energy and IFIEs by using the FMO4 method. We perform FMO4 calculations with the second order Møller-Plesset perturbation theory for an estrogen receptor (ER) and the 17?-estradiol (EST) complex using the proposed fragmentation method and assess the interaction for each ligand-binding site by the FMO4-IFIE analysis. When the steroidal EST is divided into two functional units including "A ring" and "D ring", respectively, the FMO4-IFIE analysis reveals their binding affinity with surrounding fragments of the amino acid residues; the "A ring" of EST has polarization interaction with the main chain of Thr347 and two hydrogen bonds with the side chains of Glu353 and Arg394; the "D ring" of EST has a hydrogen bond with the side chain of His524. In particular, the CH/? interactions of the "A ring" of EST with the side chains of Leu387 and Phe404 are easily identified in cooperation with the CHPI program. The FMO4-IFIE analysis using our novel subdividing fragmentation method, which provides higher resolution than the conventional IFIE analysis in units of ligand and each amino acid reside in the framework of two-body approximation, is a useful tool for revealing ligand-binding mechanism and would be applicable to rational drug design such as structure-based drug design and fragment-based drug design. PMID:23467020

Watanabe, Chiduru; Fukuzawa, Kaori; Okiyama, Yoshio; Tsukamoto, Takayuki; Kato, Akifumi; Tanaka, Shigenori; Mochizuki, Yuji; Nakano, Tatsuya

2013-04-01

248

H /D isotope effect of methyl internal rotation for acetaldehyde in ground state as calculated from a multicomponent molecular orbital method  

NASA Astrophysics Data System (ADS)

We have analyzed the differences in the methyl internal rotation induced by the H /D isotope effect for acetaldehyde (CH3CHO) and deuterated acetaldehyde (CD3CDO) in ground state by means of the multicomponent molecular orbital (MC&barbelow;MO) method, which directly accounts for the quantum effects of protons and deuterons. The rotational constant of CH3CHO was in reasonable agreement with experimental one due to the adequate treatment of the protonic quantum effect by the MC&barbelow;MO method. The C-D bond distances were about 0.007Å shorter than the C-H distances because of the effect of anharmonicity of the potential. The Mulliken population for CD3 in CD3CDO is larger than that for CH3 in CH3CHO because the distribution of wavefunctions for the deuterons was more localized than that for the protons. The barrier height obtained by the MC&barbelow;MO method for CH3CHO was estimated as 401.4cm-1, which was in excellent agreement with the experimentally determined barrier height. We predicted the barrier height of CD3CDO as 392.5cm-1. We suggest that the internal rotation of the CD3 group was more facile than that of the CH3 group because the C-D bond distance was observed to be shorter than the C-H distance. Additionally the localized electrons surrounding the CD3 group in CD3CDO caused the extent of hyperconjugation between the CD3 and CDO groups to be smaller than that in the case of CH3CHO, which may have also contributed to the observed differences in methyl internal rotation. The differences in bond distances and electronic populations induced by the H /D isotope effect were controlled by the difference in the distribution of wavefunctions between the protons and deuterons.

Ishimoto, Takayoshi; Ishihara, Yasuyuki; Teramae, Hiroyuki; Baba, Masaaki; Nagashima, Umpei

2008-05-01

249

Elliptical Orbits  

NSDL National Science Digital Library

This resource provides a textual explanation as well as animated illustration of elliptical orbits with different eccentricities. It also shows how the Sun is at the focus of an ellipse, and some of the math behind elliptical orbits. Beginner, intermediate and advanced versions of the content are available.

Roberta Johnson

2000-07-01

250

1,2-Diiododisilane and 1,1,2,2-tetraiododisilane: a reinvestigation of the molecular structures and vibrational properties by gas-phase electron diffraction, temperature dependent Raman spectroscopy, and ab initio molecular orbital- and density functional calculations  

NASA Astrophysics Data System (ADS)

The molecular structure, internal rotation and vibrational properties of 1,2-diiododisilane (DIDS), IH 2Si-SiH 2I, and 1,1,2,2-tetraiododisilane (TIDS), I 2HSi-SiHI 2, have been reinvestigated using gas phase electron diffraction (GED) data at temperatures of 55 (DIDS) and 155 (TIDS) °C, together with Raman spectroscopy, and ab initio molecular orbital (MO)- and density functional (DFT) calculations. The title compounds exist in the gas and liquid phases as a mixture of two conformers, anti ( C2 h), with a torsion angle ? (XSiSiX)=180°, and gauche ( C2), with a torsion angle ? (XSiSiX) ?60° (X=I (DIDS), X=H (TIDS)). Some structural parameter values obtained from the GED dynamic model refinements, using results from the theoretical calculations as constraints, were as follows ( anti values with estimated 2? uncertainties): For DIDS: Bond lengths ( rg): r(Si-Si)=2.315(26) Å, r(Si-I)=2.447(6) Å. Bond angles (? ?): ?SiSiI=107.5(10)°, ?ISiH=109.8(5)°. For TIDS: Bond lengths ( rg): r(Si-Si)=2.364(30) Å, r(Si-I)=2.450(6) Å, Bond angles (? ?): ?SiSiI=107.2(4)°, ?ISiH=109.9(2)°, ?ISiI=111.7(3)°. Raman vibrational spectra for various temperatures are presented and analysed aided by normal coordinate calculations and the ab initio MO- and DFT results. From intensity variations with temperature of four band pairs for DIDS and two pairs for TIDS, conformational energies in the liquids were determined from van't Hoff plots. ? H0(?? E0) values of 0.31±0.14 kcal mol -1 and 0.14±0.10 kcal mol -1 were obtained for DIDS and TIDS respectively, gauche being the low energy conformer for both disilanes.

Johansen, Tore H.; Hassler, Karl; Tekautz, Günter; Hagen, Kolbjørn

2001-12-01

251

Impact decision support diagrams  

NASA Astrophysics Data System (ADS)

One way to frame the job of planetary defense is to “find the optimal approach for finding the optimal approach” to NEO mitigation. This requires a framework for defining in advance what should be done under various circumstances. The two-dimensional action matrix from the recent NRC report “Defending Planet Earth” can be generalized to a notional “Impact Decision Support Diagram” by extending it into a third dimension. The NRC action matrix incorporated two important axes: size and time-to-impact, but probability of impact is also critical (it is part of the definitions of both the Torino and Palermo scales). Uncertainty has been neglected, but is also crucial. It can be incorporated by subsuming it into the NEO size axis by redefining size to be three standard deviations greater than the best estimate, thereby providing a built-in conservative margin. The independent variable is time-to-impact, which is known with high precision. The other two axes are both quantitative assessments of uncertainty and are both time dependent. Thus, the diagram is entirely an expression of uncertainty. The true impact probability is either one or zero, and the true size does not change. The domain contains information about the current uncertainty, which changes with time (as opposed to reality, which does not change).

Boslough, Mark

2014-10-01

252

Graph theory and molecular orbitals  

Microsoft Academic Search

The Sachs theorem [1] is discussed, and Kekulé and Sachs graphs are defined. The simple consequences of Sachs theorem which are of interest in chemistry are presented. Thus, it is shown that the pairing theorem, Hückel (4m+2) rule, and Longuet-Higgins and Dewar rule [2] can be obtained easily with the use of Sachs theorem. The dependence of the number of

A. Graovac; I. Gutman; N. Trinajsti?; T. Živkovi?

1972-01-01

253

The Hot Orbit: Orbital Cellulitis  

PubMed Central

Orbital cellulitis is an uncommon condition previously associated with severe complications. If untreated, orbital cellulitis can be potentially sight and life threatening. It can affect both adults and children but has a greater tendency to occur in the pediatric age group. The infection most commonly originates from sinuses, eyelids or face, retained foreign bodies, or distant soources by hematogenous spread. It is characterized by eyelid edema, erythema, chemosis, proptosis, blurred vision, fever, headache, and double vision. A history of upper respiratory tract infection prior to the onset is very common especially in children. In the era prior to antibiotics, vision loss from orbital cellulitis was a dreaded complication. Currently, imaging studies for detection of orbital abcess, the use of antibiotics and early drainage have mitigated visual morbidity significantly. The purpose of this review is to describe current investigative strategies and management options in the treatment of orbital cellulitis, establish their effectiveness and possible complications due to late intervention. PMID:22346113

Chaudhry, Imtiaz A.; Al-Rashed, Waleed; Arat, Yonca O.

2012-01-01

254

Density matrix method for orbital localization  

PubMed Central

A method is presented for localizing molecular orbitals, based on diagonalizing subunits of the density matrix. First, nonbonding orbitals are found by diagonalizing the monatomic subunits; then, diatomic ? or ? bonding and antibonding orbitals are obtained from the diatomic subunits for all bonded pairs of atoms; finally, the delocalized ?-orbitals for particular chromophores are found by projecting the first set out of the self-consistent field (SCF) Hamiltonian. The results show good general agreement with other localization methods, with advantages in the ability to display group orbitals in complex molecules which most closely resemble the SCF orbitals for simple prototypes. PMID:16592668

Caldwell, Dennis; Redington, Patrick; Eyring, Henry

1979-01-01

255

Program Synthesizes UML Sequence Diagrams  

NASA Technical Reports Server (NTRS)

A computer program called "Rational Sequence" generates Universal Modeling Language (UML) sequence diagrams of a target Java program running on a Java virtual machine (JVM). Rational Sequence thereby performs a reverse engineering function that aids in the design documentation of the target Java program. Whereas previously, the construction of sequence diagrams was a tedious manual process, Rational Sequence generates UML sequence diagrams automatically from the running Java code.

Barry, Matthew R.; Osborne, Richard N.

2006-01-01

256

The semigroup of Betti diagrams  

Microsoft Academic Search

The recent proof of the Boij-Soederberg conjectures reveals new structure\\u000aabout Betti diagrams of modules, giving a complete description of the cone of\\u000aBetti diagrams. We begin to expand on this new structure by investigating the\\u000asemigroup of Betti diagrams. We prove that this semigroup is finitely\\u000agenerated, and we answer several other fundamental questions about this\\u000asemigroup.

Daniel Erman

2009-01-01

257

Time Temperature Transformation (TTT) Diagrams  

E-print Network

TTT diagrams. These are salt bath (Figs. 1- 2) techniques combined with metallography and hardness techniques and thermodynamic predictions. Salt bath technique combined with metallography and hardness

Cambridge, University of

258

Orbital shrinking  

E-print Network

Jul 12, 2011 ... ... computational experiments on the tightness and solution speed of this ... variables expressing variable sums within each orbit are introduces and used to ..... limit marks an exceeded time limit of 1800 sec.s, while boldface ...

liberti

259

Orbital Decompression  

MedlinePLUS

... appearance. One of the most common indications is Graves’ disease, an autoimmune disorder that primarily affects the thyroid gland and the eye. If the eye is affected (Grave’s orbitopathy), there is an enlargement of the orbital ...

260

Orbital Dynamics  

NSDL National Science Digital Library

This video from SpaceTEC National Aerospace Technical Education Center explains the mechanics of orbital dynamics and Newton's first law of motion. This three minute video is one of the aerospace certification readiness courses.

2011-07-27

261

Orbital debris  

NASA Astrophysics Data System (ADS)

The hazard to spacecraft posed by artificial debris in orbit, though still low, is growing and requires international attention, according to a new National Research Council (NRC) report. What's more, the problem needs to be addressed while it is still manageable, the report says. First, the NRC report suggests that spacefaring nations work together make better spacecraft hazard assessments by filling in data gaps on the effects of collisions between orbiting objects and on the amount and sources of debris in orbit. Other steps include making spacecraft designers more aware of protection methods. While removal of existing debris from orbit is technically and economically infeasible, according to the report, international efforts should focus on preventive measures.

262

Theoretical phase diagrams for solid H{sub 2}  

SciTech Connect

Possible phase diagrams for solid molecular para-hydrogen in the 0-200 GPa pressure regime are constructed on the basis of ab initio calculations. Structures for the broken symmetry phase (BSP) and H-A phase have recently been proposed under the assumption that the molecules are centered on sites of a hexagonal close-packed lattice with the ideal c/a ratio, i.e., only molecular orientational and electronic changes are allowed. Symmetry considerations then dictate the simplest phase diagrams consistent with experimental observations, although the possibility of additional transitions cannot be ruled out. A simple model is introduced to describe the BSP and H-A transitions.

Surh, M.P.; Runge, K.J.

1993-07-01

263

Synthesis, Structure, and Molecular Orbital Studies of Yttrium, Erbium, and Lutetium Complexes Bearing eta(2)-Pyrazolato Ligands: Development of a New Class of Precursors for Doping Semiconductors.  

PubMed

Treatment of yttrium metal with bis(pentafluorophenyl)mercury (1.5 equiv), 3,5-di-tert-butylpyrazole (3 equiv), and pyridine (2 equiv) in toluene at ambient temperature for 120 h afforded tris(3,5-di-tert-butylpyrazolato)bis(pyridine)yttrium(III) (33%). In an analogous procedure, the reaction of erbium metal with 3,5-dialkylpyrazole (alkyl = methyl or tert-butyl), bis(pentafluorophenyl)mercury, and a neutral nitrogen donor (4-tert-butylpyridine, pyridine, n-butylimidazole, or 3,5-di-tert-butylpyrazole) yielded tris(3,5-di-tert-butylpyrazolato)bis(4-tert-butylpyridine)erbium(III) (63%), tris(3,5-di-tert-butylpyrazolato)bis(pyridine)erbium(III) (88%), tris(3,5-di-tert-butylpyrazolato)bis(n-butylimidazole)erbium(III) (48%), tris(3,5-dimethylpyrazolato)bis(4-tert-butylpyridine)erbium(III) (50%), and tris(3,5-di-tert-butylpyrazolato)(3,5-di-tert-butylpyrazole)erbium(III) (59%), respectively. Treatment of tris(cyclopentadienyl)lutetium(III) or tris(cyclopentadienyl)erbium(III) with 3,5-di-tert-butylpyrazole (3 equiv) and 4-tert-butylpyridine (2 equiv) in toluene at ambient temperature for 24 h afforded tris(3,5-di-tert-butylpyrazolato)bis(4-tert-butylpyridine)lutetium(III) (83%) and tris(3,5-di-tert-butylpyrazolato)bis(4-tert-butylpyridine)erbium(III) (41%), respectively. The X-ray crystal structures of all new complexes were determined. The X-ray structure analyses revealed seven- and eight-coordinate lanthanide complexes with all-nitrogen coordination spheres and eta(2)-pyrazolato ligands. Molecular orbital calculations were carried out on dichloro(pyrazolato)diammineyttrium(III). The calculations demonstrate that eta(2)-bonding of the pyrazolato ligand is favored over the eta(1)-bonding mode and give insight into the bonding between yttrium and the pyrazolato ligands. Complexes bearing 3,5-di-tert-butylpyrazolato ligands can be obtained in a high state of purity and sublime without decomposition (150 degrees C, 0.1 mmHg). Application of these complexes as source compounds for chemical vapor deposition processes is discussed. PMID:11671168

Pfeiffer, Dirk; Ximba, Bhekumusa J.; Liable-Sands, Louise M.; Rheingold, Arnold L.; Heeg, Mary Jane; Coleman, David M.; Schlegel, H. Bernhard; Kuech, Thomas F.; Winter, Charles H.

1999-10-01

264

W-reps, nilp orbits, orbit method  

E-print Network

W-reps, nilp orbits, orbit method David Vogan Representation theory irr reps nilp orbits irr reps W reps nilp orbits W reps Explaining the arrows Remembrance of things past Weyl group representations, nilpotent orbits, and the orbit method David Vogan Department of Mathematics Massachusetts

Vogan, David

265

Investigation of the resonance-assisted hydrogen bond in model ?-diketones through localized molecular orbital analysis of the spin-spin coupling constants related to the O-H?·?·?·?O hydrogen bond.  

PubMed

The resonance-assisted hydrogen bond (HB) phenomenon has been studied theoretically by a localized molecular orbital (LMO) decomposition of the spin-spin coupling constants between atoms either involved or close to the O-H?·?·?·?O system of some ?-diketones and their saturated counterparts. The analysis, carried out at the level of the second-order polarization propagator approximation, shows that the contributions in terms of LMO to the paramagnetic spin orbital and the spin dipolar Ramsey terms proof the importance of the delocalized ?-electron structure supporting the idea of the existence of the resonance-assisted HB phenomenon phenomenon. The LMO contributions to the Fermi contact term indicate mainly the presence of the HB that may or not be linked to the ?-electrons. Copyright © 2014 John Wiley & Sons, Ltd. PMID:25266873

Zarycz, M Natalia C; Provasi, Patricio F

2015-02-01

266

Molecular orbital (SCF-X??-SW) theory of metal-metal charge transfer processes in minerals - II. Application to Fe2+ ??? Ti4+ charge transfer transitions in oxides and silicates  

USGS Publications Warehouse

A molecular orbital description, based on X??-Scattered wave calculations on a (FeTiO10)14- cluster, is given for Fe2+ ??? Ti4+ charge transfer transitions in minerals. The calculated energy for the lowest Fe2+ ??? Ti4+ metal-metal charge transfer transition is 18040 cm-1 in reasonable agreement with energies observed in the optical spectra of Fe-Ti oxides and silicates. As in the case of Fe2+ ??? Fe3+ charge transfer in mixed-valence iron oxides and silicates, Fe2+ ??? Ti4+ charge transfer is associated with Fe-Ti bonding across shared polyhedral edges. Such bonding results from the overlap of the Fe(t2 g) and Ti(t2 g) 3 d orbitals. ?? 1987 Springer-Verlag.

Sherman, D.M.

1987-01-01

267

General Diagram-Recognition Methodologies  

Microsoft Academic Search

The field of diagram recognition faces many challenges, including the great diversity in diagrammatic notations, and the presence of noise and ambiguity during the recognition process. To help address these problems, research is needed into methods for acquiring, representing, and exploiting notational conventions. We review several frameworks for diagram recognition: blackboard systems, schema-based systems, syntactic methods, and graph rewriting. Next

Dorothea Blostein

1995-01-01

268

Force Diagrams: How? and Why?  

ERIC Educational Resources Information Center

Suggests that physics students always have three questions when using force diagrams: (1) Why do I need one? (2) How do I draw one? and (3) How do I find the forces acting on a body? Provides a method to help students find answers to all three questions and understand force diagrams. (MVL)

Newburgh, Ronald

1994-01-01

269

Perturbations to the Hubble diagram  

E-print Network

We compute the linear responses of the Hubble diagram to small scalar perturbations in the Robertson-Walker metric and to small peculiar velocities of emitter and receiver. We discuss the monotonicity constraint of the Hubble diagram in the light of these responses.

Thomas Schucker; Ilhem ZouZou

2005-11-17

270

Physiology Flow-Diagram Models  

NSDL National Science Digital Library

A set of physiology flow-diagrams for the cardiovascular system, cardiac auto-rhythmic cell, cardiac contractile cell, respiratory system, coagulation/hemostasis, digestive system, excretion, and autonomic nervous system. These flow-diagrams show cause-and-effect markup and have accompanying tutorials.

PhD Sandra J Bruner (Polk Community College Biology)

2005-10-04

271

4,5-Dicyano-3,6-diethylbenzo-1,2-diselenete, a highly stable 1,2-diselenete: its preparation, structural characterization, calculated molecular orbitals, and complexation with tetrakis(triphenylphosphine)palladium.  

PubMed

The first isolable benzo-1,2-diselenete, 4,5-dicyano-3,6-diethylbenzo-1,2-diselenete (4), was prepared by the reaction of 4,5-(o-xylylenediseleno)-3,6-diethylphthalonitrile (3) with aluminum chloride in toluene. X-ray crystallographic analysis demonstrated that 4 contains a trapezoidal diselenide ring rather than a benzo-1,2-diselenone structure. In crystal form, 4 undergoes self-assembly and generates structures based on layered molecular sheets since the unit cell contains only one molecule. While the cyclic voltammogram of 4 exhibited only one irreversible peak (Ep = 1.59 V) during oxidation and two quasireversible couples during reduction, three peaks were observed in the differential pulse voltammogram of the reduction couples (E1/2 = -1.19, -0.75, and -0.69 V). Although a THF solution of 4 in the presence of sodium metal was EPR silent, various signals were readily observed in its (1)H, (13)C, and (77)Se NMR spectra. Molecular orbital calculations for 4 demonstrated that the HOMO orbital is primarily localized at the two selenium atoms and four of the benzene carbon atoms while the LUMO orbital is situated solely on the diselenete ring. It appears that the HOMO and LUMO orbitals of 4 receive significant stabilization from the nitrile groups compared to the level of stabilization in the unsubstituted benzo-1,2-diselenete (BDS). The reaction of 4 with tetrakis(triphenylphosphine)palladium in benzene was found to produce a dinuclear palladium complex (8), and the structure of this complex was determined by X-ray crystallographic analysis. The central four membered ring of 8 consists of the Pd1, Se2, Pd2, and Se3 atoms and is not planar but rather adopts a folded arrangement. PMID:24724937

Kimura, Takeshi; Nakahodo, Tsukasa; Fujihara, Hisashi; Suzuki, Eiichi

2014-05-01

272

Achieving Orbit  

NSDL National Science Digital Library

In this Engineering Design Challenge activity, learners will use balloons to investigate how a multi-stage rocket, like that used in the Interstellar Boundary Explorer (IBEX) mission, can propel a satellite to a specific orbit. Participants will construct a two-stage balloon rocket that will be required to reach a particular location on the balloon track, simulating the proper orbit to be reached by the IBEX satellite. If you need an audio version of this material, the file is compatible with screen reading software such as Adobe Acrobat Reader.

2012-07-17

273

Phase diagram of the extended Ashkin-Teller model  

NASA Astrophysics Data System (ADS)

Possible generalizations of the Ashkin-Teller model are analysed aiming at reduction of degeneracy of the energy levels. The extended isotropic case is considered in the framework of the molecular field approximation. Assuming six order parameters a three dimensional phase diagram is calculated.

Pawlicki, P.; Rogiers, J.; Kamieniarz, G.

1995-02-01

274

Vanishing rainbows near orbiting and the energy dependence of rainbow scattering - Relation to properties of the potential. [molecular beam scattering cross sections  

NASA Technical Reports Server (NTRS)

The energy threshold behavior of elastic rainbow scattering near the transition to orbiting is derived. Analysis of the energy dependence of the rainbow angle shows that the full range from high energies down to orbiting can be fitted with two parameters. Thus, measurements of the rainbow angle can give essentially only two pieces of information about the potential. For potentials of common shapes, such measurements are sensitive to regions of the potential just beyond the minimum and give information about the shape of the potential in this range. However, neither a minimum nor a point of inflection in the potential is necessary for rainbow scattering.

Greene, E. F.; Hall, R. B.; Mason, E. A.

1975-01-01

275

Orbital Elements  

NSDL National Science Digital Library

Coordinates for tracking the International Space Station and the Mir Space Station are available here from NASA's Johnson Space Center Flight Design and Dynamics Division. The Orbital Elements page offers real-time data for use in ground track plotting programs. The site cautions the data are for ground track plotting programs only and "should not be used for precise applications or analysis!"

276

Elliptical Orbits  

NSDL National Science Digital Library

Although not inquiry, this activity is important for students to understand what an ellipse is and what a focus is, and to break misconceptions about Earth's orbit being highly elliptical. This is the perfect place to check to see if students have the mis

Horton, Michael

2009-05-30

277

Compound orbits break-up in constituents: an algorithm  

E-print Network

In this paper decomposition of periodic orbits in bifurcation diagrams are derived in unidimensional dynamics system $x_{n+1}=f(x_{n};r)$, being $f$ an unimodal function. We proof a theorem which states the necessary and sufficient conditions for the break-up of compound orbits in their simpler constituents. A corollary to this theorem provides an algorithm for the computation of those orbits. This process closes the theoretical framework initiated in (Physica D, 239:1135--1146, 2010).

Jesús San Martín; A. González Gómez; Ma José Moscoso; Daniel Rodríguez-Pérez

2014-02-24

278

Spectroscopy, crystal structure, valance molecular orbital energy level diagram and DFT study of cis-[Cr(2,2'-bipy)2Cl2](Cl)0.38(PF6)0.62.  

PubMed

A new octahedral chromium(III) complex having 2,2'-bipyridine as ligand system was synthesized in methanol. Single crystal X-ray diffraction analysis shows that it possesses non-stoichiometry in its anionic primary covalency. It has also been studied by elemental analyses, optical spectroscopy (UV-vis, IR) and magnetic susceptibility data. DFT calculations (with B3LYP functional and double-xi quality LANLDZ(D95V) basis set) were carried out to interpret the electronic and infrared spectra of the complex. The DFT optimized geometric structure for the complex is compared with the X-ray crystallographic data; the theory-experiment agreement is satisfactory. PMID:16677852

Kar, Tapas; Liao, Meng-Sheng; Biswas, Susobhan; Sarkar, Saikat; Dey, Kamalendu; Yap, Glenn P A; Kreisel, Kevin

2006-11-01

279

Molecular Menagerie  

NSDL National Science Digital Library

In this activity, learners use molecular model kits to construct familiar molecules like lactose, caffeine, and Aspirin. This activity helps learners understand how scientists use models to study molecules as well as how advances in 3-D graphics have made the use of computer models much easier. This activity guide includes chemical formulas and 3-D structural diagrams of various natural and artificial molecules. Note: the cost of molecular model kits is included in the estimated cost of materials.

Howard Hughes Medical Institute

2002-01-01

280

Payload/orbiter contamination control requirement study  

NASA Technical Reports Server (NTRS)

A study was conducted to determine and quantify the expected particulate and molecular on-orbit contaminant environment for selected space shuttle payloads as a result of major shuttle orbiter contamination sources. Individual payload susceptibilities to contamination are reviewed. The risk of payload degradation is identified and preliminary recommendations are provided concerning the limiting factors which may depend on operational activities associated with the payload/orbiter interface or upon independent payload functional activities. A basic computer model of the space shuttle orbiter which includes a representative payload configuration is developed. The major orbiter contamination sources, locations, and flux characteristics based upon available data have been defined and modeled.

Bareiss, L. E.; Rantanen, R. O.; Ress, E. B.

1974-01-01

281

Molecular orbital studies (hardness, chemical potential, electronegativity and electrophilicity), vibrational spectroscopic investigation and normal coordinate analysis of 5-{1-hydroxy-2-[(propan-2-yl)amino]ethyl}benzene-1,3-diol  

NASA Astrophysics Data System (ADS)

FT-IR and FT-Raman spectra of 5-{1-hydroxy-2-[(propan-2-yl) amino] ethyl} benzene-1,3-diol (abbrevi- 54 ated as HPAEBD) were recorded in the region 4000-450 cm-1 and 4000-100 cm-1 respectively. The structure of the molecule was optimized and the structural characteristics were determined by density functional theory (B3LYP) and HF method with 6-31 G(d,p) as basis set. The theoretical wave numbers were scaled and compared with experimental FT-IR and FT-Raman spectra. A detailed interpretation of the vibrational spectra of this compound has been made on the basis of the calculated Potential energy distribution (PED). Stability of the molecule arising from hyperconjugation and charge delocalization is confirmed by the natural bond orbital analysis (NBO). The results show that electron density (ED) in the ? antibonding orbitals and E (2) energies confirm the occurrence of intra molecular charge transfer (ICT) within the molecule. The molecule orbital contributions were studied by using the total (TDOS), sum of ? and ? electron (??DOS) density of States. Mulliken population analysis of atomic charges is also calculated. The calculated HOMO and LUMO energy gap shows that charge transfer occurs within the molecule. The electron density-based local reactivity descriptors such as Fukui functions were calculated to explain the chemical selectivity or reactivity site in this compound. On the basis of vibrational analyses, the thermodynamic properties of title compound at different temperatures have been calculated.

Muthu, S.; Renuga, S.

2014-01-01

282

Molecular orbital studies (hardness, chemical potential, electronegativity and electrophilicity), vibrational spectroscopic investigation and normal coordinate analysis of 5-{1-hydroxy-2-[(propan-2-yl)amino]ethyl}benzene-1,3-diol.  

PubMed

FT-IR and FT-Raman spectra of 5-{1-hydroxy-2-[(propan-2-yl) amino] ethyl} benzene-1,3-diol (abbrevi- 54 ated as HPAEBD) were recorded in the region 4000-450 cm(-1) and 4000-100 cm(-1) respectively. The structure of the molecule was optimized and the structural characteristics were determined by density functional theory (B3LYP) and HF method with 6-31 G(d,p) as basis set. The theoretical wave numbers were scaled and compared with experimental FT-IR and FT-Raman spectra. A detailed interpretation of the vibrational spectra of this compound has been made on the basis of the calculated Potential energy distribution (PED). Stability of the molecule arising from hyperconjugation and charge delocalization is confirmed by the natural bond orbital analysis (NBO). The results show that electron density (ED) in the ? antibonding orbitals and E (2) energies confirm the occurrence of intra molecular charge transfer (ICT) within the molecule. The molecule orbital contributions were studied by using the total (TDOS), sum of ? and ? electron (??DOS) density of States. Mulliken population analysis of atomic charges is also calculated. The calculated HOMO and LUMO energy gap shows that charge transfer occurs within the molecule. The electron density-based local reactivity descriptors such as Fukui functions were calculated to explain the chemical selectivity or reactivity site in this compound. On the basis of vibrational analyses, the thermodynamic properties of title compound at different temperatures have been calculated. PMID:24096064

Muthu, S; Renuga, S

2014-01-24

283

The Hertzsprung-Russell Diagram.  

ERIC Educational Resources Information Center

Describes a classroom use of the Hertzsprung-Russell diagram to infer not only the properties of a star but also the star's probable stage in evolution, life span, and age of the cluster in which it is located. (ZWH)

Woodrow, Janice

1991-01-01

284

Interpreting T-X Diagrams  

NSDL National Science Digital Library

This short problem set works well as a group activity that can be completed in class. The purpose of the exercise is for students to begin to think about T-X phase diagrams and how they are interpreted. Along the way, students learn that text book authors sometimes make mistakes. The figure in the handout is from Winter's Petrology. But, Winter goofed and left some reactions off of the phase diagram.

Perkins, Dexter

285

Molecular orbital studies (hardness, chemical potential and electrophilicity), vibrational investigation and theoretical NBO analysis of 4-4'-(1H-1,2,4-triazol-1-yl methylene) dibenzonitrile based on abinitio and DFT methods.  

PubMed

The Fourier transform infrared (FTIR) and FT Raman (FTR) of 4-4'-(1H-1, 2, 4-triazol-1-yl methylene) dibenzonitrile (4-HTMDBN) have been recorded and analyzed. The equilibrium geometry harmonic vibrational frequencies have been investigated with the help of standard HF and DFT methods with 6-31G(d,p) as basis set. The assignments of the vibrational spectra have been carried out with the help of normal co-ordinate analysis (NCA) following the scaled quantum mechanical force field methodology (SQMFF). Theoretical simulations of the FTIR and FTR spectra of the title compound have been calculated. The (1)H and (13)C Nuclear Magnetic Resonance (NMR) chemical shifts of the molecule were calculated by the Gauge including atomic orbital (GIAO) method. The stability of the molecule has been analyzed using natural bond orbital (NBO) analysis. The linear polarizability (?) and the first order hyperpolarizability (?) values of the investigated molecule have been computed using HF/DFT/6-31G(d,p) methods on the finite field approach. UV-Vis spectrum of the compound is recorded and the electronic properties such as HOMO and LUMO energies, are performed. The directly calculated ionization potential (IP), electron affinity (EA), electronegativity (?), electrophilicity index (?), hardness (?) and chemical potential (?) are all correlated with the HOMO and LUMO energies with their molecular properties. Mulliken population analysis on atomic charges, molecular electrostatic potential maps (MEP) and thermodynamical properties of title compound at different temperature have been calculated. PMID:24184626

Sheela, N R; Muthu, S; Sampathkrishnan, S

2014-01-01

286

Orbiting Hotel  

NSDL National Science Digital Library

It is the year 2025 and a large company, Z-Tech, wants to put a hotel in space having it orbit around one of the planets in our solar system. Our 9th grade class has been given a very important job. We have to search for the perfect location for the hotel. Our job is to report back to the company with the planet that is the best place for an orbiting hotel. The Task: You are to write a report recommending which planet should be chosen. Your report should include pictures of the planet you recommended. Here are the questions you should answer in order to report back to Z-Tech with your recommendation. * Which planet will be the ...

Hicken, Mrs.

2009-10-19

287

Theory of satellite orbit-orbit resonance  

Microsoft Academic Search

On the basis of the strong mathematical and physical parallels between orbit-orbit and spin-orbit resonances, the dynamics of mutual orbit perturbations between two satellites about a massive planet are examined, exploiting an approach previously adopted in the study of spin-orbit coupling. The satellites are assumed to have arbitrary mass ratio and to move in non-intersecting orbits of arbitrary size and

Leon Blitzer; John D. Anderson

1981-01-01

288

Studies of the electron density in the highest occupied molecular orbitals of PH 3, PF 3 and P(CH 3) 3 by electron momentum spectroscopy and Hartree-Fock, MRSD-CI and DFT calculations  

NASA Astrophysics Data System (ADS)

The spherically averaged momentum profiles for the highest occupied molecular orbitals of PF 3 and P(CH 3) 3 have been obtained by electron momentum spectroscopy. The measurements provide a stringent test of basis set effects and the quality of ab-initio methods in the description of these larger molecular systems. As in previous work on the methyl-substituted amines, intuitive arguments fail to predict the correct amount of s- and p-type contributions to the momentum profile while delocalized molecular orbital concepts provide a more adequate description of the HOMOs. The experimental momentum profiles have been compared with theoretical momentum profiles calculated at the level of the target Hartree-Fock approximation with a range of basis sets. New Hartree-Fock calculations are also presented for the HOMO of PH 3 and compared to previously published experimental and theoretical momentum profiles. The experimental momentum profiles have further been compared to calculations at the level of the target Kohn-Sham approximation using density functional theory with the local density approximation and also with gradient corrected (non-local) exchange correlation potentials. In addition, total energies and dipole moments have been calculated for all three molecules by the various theoretical methods and compared to experimental values. Calculated 'density difference maps' show the regions where the HOMO momentum and position electron densities of PF 3 and P(CH 3) 3 change relative to the corresponding HOMO density of PH 3. The results suggest that methyl groups have an electron-attracting effect (relative to H) on the HOMO charge density in trimethyl phosphines. These conclusions are supported by a consideration of dipole moments and the 31P NMR chemical shifts for PH 3, PF 3 and P(CH 3) 3.

Rolke, J.; Brion, C. E.

1996-06-01

289

Dynamical evolution of active detached binaries on log Jo - log M diagram and contact binary formation  

E-print Network

Orbital angular momentum (Jo), systemic mass (M) and orbital period (P) distributions of chromospherically active binaries (CAB) and W Ursae Majoris (W UMa) systems were investigated. The diagrams of log Jo - log P, log M - log P and log Jo-log M were formed from 119 CAB and 102 W UMa stars. The log Jo-log M diagram is found to be most meaningful in demonstrating dynamical evolution of binary star orbits. A slightly curved borderline (contact border) separating the detached and the contact systems was discovered on the log Jo - log M diagram. Since orbital size (a) and period (P) of binaries are determined by their current Jo, M and mass ratio q, the rates of orbital angular momentum loss (dlog Jo/dt) and mass loss (dlog M/dt) are primary parameters to determine the direction and the speed of the dynamical evolution. A detached system becomes a contact system if its own dynamical evolution enables it to pass the contact border on the log Jo - log M diagram. Evolution of q for a mass loosing detached system is...

Eker, Z; Bilir, S; Karatas, Y

2006-01-01

290

Dynamical evolution of active detached binaries on log Jo - log M diagram and contact binary formation  

E-print Network

Orbital angular momentum (Jo), systemic mass (M) and orbital period (P) distributions of chromospherically active binaries (CAB) and W Ursae Majoris (W UMa) systems were investigated. The diagrams of log Jo - log P, log M - log P and log Jo-log M were formed from 119 CAB and 102 W UMa stars. The log Jo-log M diagram is found to be most meaningful in demonstrating dynamical evolution of binary star orbits. A slightly curved borderline (contact border) separating the detached and the contact systems was discovered on the log Jo - log M diagram. Since orbital size (a) and period (P) of binaries are determined by their current Jo, M and mass ratio q, the rates of orbital angular momentum loss (dlog Jo/dt) and mass loss (dlog M/dt) are primary parameters to determine the direction and the speed of the dynamical evolution. A detached system becomes a contact system if its own dynamical evolution enables it to pass the contact border on the log Jo - log M diagram. Evolution of q for a mass loosing detached system is unknown unless mass loss rate for each component is known. Assuming q is constant in the first approximation and using the mean decreasing rates of Jo and M from the kinematical ages of CAB stars, it has been predicted that 11, 23 and 39 cent of current CAB stars would transform to W UMa systems if their nuclear evolution permits them to live 2, 4 and 6 Gyrs respectively.

Z. Eker; O. Demircan; S. Bilir; Y. Karatas

2006-09-14

291

Orbit analysis  

SciTech Connect

The past fifteen years have witnessed a remarkable development of methods for analyzing single particle orbit dynamics in accelerators. Unlike their more classic counterparts, which act upon differential equations, these methods proceed by manipulating Poincare maps directly. This attribute makes them well matched for studying accelerators whose physics is most naturally modelled in terms of maps, an observation that has been championed most vigorously by Forest. In the following sections the author sketchs a little background, explains some of the physics underlying these techniques, and discusses the best computing strategy for implementing them in conjunction with modeling accelerators.

Michelotti, L.

1995-01-01

292

Phase Diagram of Glass Forming Liquids with Randomly Pinned Particles  

E-print Network

Extensive molecular dynamics simulations are performed to determine the phase diagram of two model glass forming liquids in the presence of external quenched disorder. The quenched disorder is introduced in the system by randomly choosing a fraction $\\rho_{pin}$ of particles from an equilibrium configuration of the supercooled liquids at temperature $T$ and freezing them in space. The study of the dynamics of supercooled liquids with this type of quenched disorder has drawn a lot of attention in recent years due to theoretical predictions of the possibility of observing the ideal thermodynamic glass transition in such systems. In this Letter, we numerically examine this possibility by determining the phase diagram of the systems in the $\\rho_{pin}-T$ plane. We find that the phase diagram differs considerably from existing theoretical predictions and show that a rapid decrease in the kinetic fragility of the system with increasing pin concentration is a probable reason for this difference.

Saurish Chakrabarty; Smarajit Karmakar; Chandan Dasgupta

2014-05-14

293

High-Resolution Soft X-Ray Spectral Analysis in the CK Region of Titanium Carbide (TiC) using the DV-X alpha Molecular Orbital Method  

SciTech Connect

We used the DV-X alpha method to analyze the high-resolution soft X-ray emission and absorption spectra in the CK region of titanium carbide (TiC). The spectral profiles of the X-ray emission and absorption can be ssuscfucelly reproduced by the occupied and unoccupied density of states (DOS ), respectively, in the C2p orbitals of the center carbon atoms in a Ti62C63 cluster model, suggesting that the center carbon atom in a large cluster model expanded to the cubic-structured 53 (= 125) atoms provides sufficient DOS for the X-ray spectral analysis of rock-salt structured metal carbides.

Shimomura, Kenta; Muramatsu, Yasuji; Denlinger, Jonathan D.; Gullikson, Eric M.

2008-10-31

294

NAAP HR Diagram Explorer 1/9 HR Diagram Student Guide  

E-print Network

Name: NAAP ­ HR Diagram Explorer 1/9 HR Diagram ­ Student Guide Background Information Work through Orionis O9 Radius (R) Temperature (T) Luminosity (L) 1 1 1 2 1 9 1 1/2 #12;NAAP ­ HR Diagram Explorer 2 Diagram Explorer Open the HR Diagram Explorer. Begin by familiarizing yourself with the capabilities

Farritor, Shane

295

Spin and orbital magnetic moments of molecular beam epitaxy ?'-Fe4N films on LaAlO3(001) and MgO(001) substrates by x-ray magnetic circular dichroism  

NASA Astrophysics Data System (ADS)

10-nm-thick ?'-Fe4N films were grown epitaxially on LaAlO3(001) and MgO(001) substrates by molecular beam epitaxy using solid Fe and a radio-frequency NH3 plasma. The lattice mismatch of these substrates to ?'-Fe4N is 0% and 11%, respectively. Spin and orbital magnetic moments of these ?'-Fe4N epitaxial films were deduced by x-ray magnetic circular dichroism measurements at 300 K. The total magnetic moments are almost the same for the two substrates, that is, 2.44±0.06 ?B and 2.47±0.06 ?B, respectively. These values are very close to those predicted theoretically, and distinctively larger than that for ?-Fe.

Ito, K.; Lee, G. H.; Harada, K.; Suzuno, M.; Suemasu, T.; Takeda, Y.; Saitoh, Y.; Ye, M.; Kimura, A.; Akinaga, H.

2011-03-01

296

Rhenium oxide as an efficient p-dopant to overcome S-shaped current density-voltage curves in organic photovoltaics with a deep highest occupied molecular orbital level donor layer  

NASA Astrophysics Data System (ADS)

Effect of p-dopants in a p-doped hole transport layer inserted between indium tin oxide and a donor layer of ?,?'-bis(2,2-dicyanovinyl)-quinquethiophene with a deep highest occupied molecular orbital level is reported to remove the S-shape in the organic photovoltaics (OPV) cell. Among the p-dopants of ReO3, MoO3, WO3, and CuI, ReO3 possesses the largest work function and turns out to be the most efficient p-dopant to remove the S-shape of the current density-voltage curve in the OPV cells. The rest of the dopants could not get rid of the S-shape, even with a doping concentration of 25 mol. %. The difference among the dopants can be understood by the different charge generation efficiency of the dopants.

Kim, Dae-Ho; Kim, Tae-Min; Jeong, Won-Ik; Kim, Jang-Joo

2012-10-01

297

Index of Animated Phase Diagrams  

NSDL National Science Digital Library

This is a collection of animated phase diagrams by Kenneth Windom at Iowa State University. These short Power Point animations can be used to illustrate equilibrium crystallization concepts. There are slide shows for plagioclase feldspars (albite and anorthite); forsterite, diopside and anorthite; forsterite, enstatite and silica; and diopside and anorthite.

Windom, Kenneth E.; University, Iowa S.

298

Reasoning with Diagrams: Final Report  

Microsoft Academic Search

The standard notation for modelling software systems is the Unified Modelling Language (UML). This consists of a suite of mainly diagrammatic notations. However, UML's constraint language, OCL, is entirely textual, making the notation less accessible to practitioners. The Reasoning with Diagrams project aims to build the foundation for more accessible no-tations for practitioners, building on and consolidating ex-isting theoretical and

John Howse; Richard Bosworth; Andrew Fish; John Taylor; Peter Rodgers; Gem Stapleton; Simon Thompson

299

Voronoi Diagrams and Spring Rain  

ERIC Educational Resources Information Center

The goal of this geometry project is to use Voronoi diagrams, a powerful modeling tool across disciplines, and the integration of technology to analyze spring rainfall from rain gauge data over a region. In their investigation, students use familiar equipment from their mathematical toolbox: triangles and other polygons, circumcenters and…

Perham, Arnold E.; Perham, Faustine L.

2011-01-01

300

Telesynergy V3 Wiring Diagram  

Cancer.gov

Extron 8 port Video/Audio Switch WAVE Camera Telesynergy v3 Wiring Diagram ISDN T1/PRI Module CTRLR 0 Legend: S-Video Audio VGA DVI USB RS-232 Serial Microphone Ethernet Planar C5i AMD Exam Cam Canon Document Camera Olympus BX51 Sony DVD Recorder JVC

301

INCONEL 718: A solidification diagram  

Microsoft Academic Search

As part of a program studying weldability of Ni-base superalloys, results of an integrated analytical approach are used to generate a constitution diagram for INCONEL 718* in the temperature range associated with solidification. Differential thermal analysis of wrought material and optical and scanning electron microscopy, electron probe microanalysis, and analytical electron microscopy of gas tungsten arc welds are used in

G. A. Knorovsky; M. J. Cieslak; T. J. Headley; A. D. Romig; W. F. Hammetter

1989-01-01

302

Analysis of the electronic structure of liquid rubidium by the methods of ab initio molecular dynamics, linear muffin-tin orbitals and recursion.  

PubMed

It is well known that liquid rubidium shows some unusual properties at low densities. The ab initio SIESTA package and the supercell technique within the linear muffin-tin orbital method were used to investigate this phenomenon. Electronic structures of liquid rubidium at different temperatures from the melting point up to the critical point were obtained. The atomic structure for the supercell technique was simulated for a cluster of 4000 atoms by the Schommers method on the basis of experimental structure factors of Rb obtained by Tamura and co-workers at different temperatures (from 373 up to 1973 K). The Kubo-Greenwood formula was applied for the calculations of the melt conductivity. The results obtained indicate that the metal-nonmetal transition in liquid rubidium is not connected to the gap at the Fermi energy in the density of electronic states, but, more likely, with electron localization on some kind of atomic cluster. PMID:21694197

Mirzoev, A A; Mirzoev, A A; Sobolev, A N; Gelchinski, B R

2008-03-19

303

Space shuttle on-orbit flight control software requirements, preliminary version  

NASA Technical Reports Server (NTRS)

Software modules associated with various flight control functions for the space shuttle orbiter are described. Data flow, interface requirements, initialization requirements and module sequencing requirements are considered. Block diagrams and tables are included.

1975-01-01

304

Shapes of d Orbitals  

NSDL National Science Digital Library

Shapes of d Orbitals shows the d orbitals in an axis set. Running the mouse over an orbital reveals the "name" of that orbital. This is good practice for helping students link the name of an orbital to the orientation.Shapes of d Orbitals has a link to D Orbitals in an Octahedral Ligand Field. Here the user may click on the name of any one of the d orbitals to obtain a larger 3-dimensional image. The images are rotatable and scalable. Orbital phase is shown by the different colors.

305

Orbiter/launch system  

NASA Technical Reports Server (NTRS)

The system includes reusable turbojet propelled booster vehicles releasably connected to a reusable rocket powered orbit vehicle. The coupled orbiter-booster combination takes off horizontally and ascends to staging altitude and speed under booster power with both orbiter and booster wings providing lift. After staging, the booster vehicles fly back to Earth for horizontal landing and the orbiter vehicle continues ascending to orbit.

Jackson, L. R.; Weidner, J. P.; Small, W. J.; Martin, J. A. (inventors)

1981-01-01

306

Triton clustering in neutron rich nuclei and Ikeda - like diagrams  

E-print Network

It is shown here that new experiments confirm author's recent prediction of a strong tendency for triton clustering in light neutron rich nuclei. As such the neutron halo phenomena is naturally explained here. Prediction of exotic molecular states rich in tritonic clusters is made here through new Ikeda-like diagram configurations for the nuclei ${^{3Z}_Z} A_{2Z}$ . Hence this model is well confirmed experimentally and makes several new predictions which can be tested experimentally.

Afsar Abbas

2003-07-14

307

Mapping the Topological Phase Diagram of Multiband Semiconductors with Supercurrents  

NASA Astrophysics Data System (ADS)

We show that Josephson junctions made of multiband semiconductors with strong spin-orbit coupling carry a critical supercurrent Ic that contains information about the nontrivial topology of the system. In particular, we find that the emergence and annihilation of Majorana bound states in the junction is reflected in strong even-odd effects in Ic at small junction transparency. This effect allows for a mapping between Ic and the topological phase diagram of the junction, thus providing a dc measurement of its topology.

San-Jose, Pablo; Prada, Elsa; Aguado, Ramón

2014-04-01

308

Orbit design concepts for Jupiter orbiter missions  

NASA Technical Reports Server (NTRS)

Advanced mission and orbit planning efforts are currently in progress for a Mariner-class Jupiter orbiter. Baseline spacecraft and orbit design criteria are the goals of a NASA effort to define such a mission. Orbit design concepts that have been discovered during the early stages of mission planning are both challenging and exciting. A description is given of several such concepts that may greatly increase the flexibility and scientific return of orbiters designed for close study of the Galilean satellites and exploration of the Jovian system. Some new jargon is introduced in discussions to describe the exploitation of gravity-assist trajectories using the giant satellites for orbit control. Orbit 'pumping' and 'cranking' and 'resonance hopping' are defined and shown to be dynamically feasible means of controlling the orbit and, thus, the scientific return. A candidate encounter sequence is presented for an equatorial tour of the Galilean moons.

Uphoff, C.; Roberts, P. H.; Friedman, L. D.

1974-01-01

309

Chord diagrams and BPHZ subtractions  

E-print Network

The combinatorics of the BPHZ subtraction scheme for a class of ladder graphs for the three point vertex in $\\phi^3$ theory is transcribed into certain connectivity relations for marked chord diagrams (knots with transversal intersections). The resolution of the singular crossings using the equivalence relations in these examples provides confirmation of a proposed fundamental relationship between knot theory and renormalization in perturbative quantum field theory.

Ioannis Tsohantjis; Alex C Kalloniatis; Peter D Jarvis

1996-04-30

310

Projected seniority-two orbital optimization of the antisymmetric product of one-reference orbital geminal  

NASA Astrophysics Data System (ADS)

We present a new, non-variational orbital-optimization scheme for the antisymmetric product of one-reference orbital geminal wave function. Our approach is motivated by the observation that an orbital-optimized seniority-zero configuration interaction (CI) expansion yields similar results to an orbital-optimized seniority-zero-plus-two CI expansion [L. Bytautas, T. M. Henderson, C. A. Jimenez-Hoyos, J. K. Ellis, and G. E. Scuseria, J. Chem. Phys. 135, 044119 (2011)]. A numerical analysis is performed for the C2 and LiF molecules, for the CH2 singlet diradical as well as for the symmetric stretching of hypothetical (linear) hydrogen chains. For these test cases, the proposed orbital-optimization protocol yields similar results to its variational orbital optimization counterpart, but prevents symmetry-breaking of molecular orbitals in most cases.

Boguslawski, Katharina; Tecmer, Pawe?; Limacher, Peter A.; Johnson, Paul A.; Ayers, Paul W.; Bultinck, Patrick; De Baerdemacker, Stijn; Van Neck, Dimitri

2014-06-01

311

Projected seniority-two orbital optimization of the antisymmetric product of one-reference orbital geminal.  

PubMed

We present a new, non-variational orbital-optimization scheme for the antisymmetric product of one-reference orbital geminal wave function. Our approach is motivated by the observation that an orbital-optimized seniority-zero configuration interaction (CI) expansion yields similar results to an orbital-optimized seniority-zero-plus-two CI expansion [L. Bytautas, T. M. Henderson, C. A. Jimenez-Hoyos, J. K. Ellis, and G. E. Scuseria, J. Chem. Phys. 135, 044119 (2011)]. A numerical analysis is performed for the C2 and LiF molecules, for the CH2 singlet diradical as well as for the symmetric stretching of hypothetical (linear) hydrogen chains. For these test cases, the proposed orbital-optimization protocol yields similar results to its variational orbital optimization counterpart, but prevents symmetry-breaking of molecular orbitals in most cases. PMID:24907997

Boguslawski, Katharina; Tecmer, Pawe?; Limacher, Peter A; Johnson, Paul A; Ayers, Paul W; Bultinck, Patrick; De Baerdemacker, Stijn; Van Neck, Dimitri

2014-06-01

312

INCONEL 718: A solidification diagram  

NASA Astrophysics Data System (ADS)

As part of a program studying weldability of Ni-base superalloys, results of an integrated analytical approach are used to generate a constitution diagram for INCONEL 718* in the temperature range associated with solidification. Differential thermal analysis of wrought material and optical and scanning electron microscopy, electron probe microanalysis, and analytical electron microscopy of gas tungsten arc welds are used in conjunction with solidification theory to generate data points for this diagram. The important features of the diagram are an austenite (?)/Laves phase eutectic which occurs at ?19.1 wt pct Nb between austenite containing ?9.3 wt pct Nb and a Laves phase which contains ?22.4 wt pct Nb. The distribution coefficient for Nb was found to be ?0.5. The solidification sequence of INCONEL 718 was found to be (1) proeutectic ?, followed by (2) a ?/NbC eutectic at ?1250°C, followed by (3) continued ? solidification, followed by (4) a ?/Laves phase eutectic at ?1200°C. An estimate of the volume fraction eutectic is made using the Scheil solidification model, and the fraction of each phase in the eutectic is calculated via the lever rule. These are compared with experimentally determined values and found to be in good agreement.

Knorovsky, G. A.; Cieslak, M. J.; Headley, T. J.; Romig, A. D.; Hammetter, W. F.

1989-10-01

313

Causal diagrams in systems epidemiology  

PubMed Central

Methods of diagrammatic modelling have been greatly developed in the past two decades. Outside the context of infectious diseases, systematic use of diagrams in epidemiology has been mainly confined to the analysis of a single link: that between a disease outcome and its proximal determinant(s). Transmitted causes ("causes of causes") tend not to be systematically analysed. The infectious disease epidemiology modelling tradition models the human population in its environment, typically with the exposure-health relationship and the determinants of exposure being considered at individual and group/ecological levels, respectively. Some properties of the resulting systems are quite general, and are seen in unrelated contexts such as biochemical pathways. Confining analysis to a single link misses the opportunity to discover such properties. The structure of a causal diagram is derived from knowledge about how the world works, as well as from statistical evidence. A single diagram can be used to characterise a whole research area, not just a single analysis - although this depends on the degree of consistency of the causal relationships between different populations - and can therefore be used to integrate multiple datasets. Additional advantages of system-wide models include: the use of instrumental variables - now emerging as an important technique in epidemiology in the context of mendelian randomisation, but under-used in the exploitation of "natural experiments"; the explicit use of change models, which have advantages with respect to inferring causation; and in the detection and elucidation of feedback. PMID:22429606

2012-01-01

314

Guelph Physics Tutorials: Free Body Diagrams  

NSDL National Science Digital Library

This website offers a tutorial on free body diagrams. The tutorial includes an introduction to free body diagrams, example problems, a series of self-paced questions, and a free body diagram java applet. This is part of series of tutorials on physics and mathematics used in physics classes.

2007-04-23

315

On hooks of Young diagrams Christine Bessenrodt  

E-print Network

On hooks of Young diagrams Christine Bessenrodt Fakult¨at f¨ur Mathematik Otto re­ movable box for a Young diagram is generalized to arbitrary hooks. As an application originated from a conjecture by Regev and Vershik on hook num­ bers in certain skew Young diagrams, described

Bessenrodt, Christine

316

Shuttle Orbiter Uplink Text and Graphics System  

NASA Technical Reports Server (NTRS)

This paper presents the definition of requirements for and current design of the Shuttle Orbiter Uplink Text and Graphics System (UT&GS). Beginning in early 1981, the UT&GS will support Shuttle flights by providing the capability of transmitting single-frame imagery from the ground to the orbiting Shuttle vehicle. Such imagery is in the form of maps, text, diagrams, or photographs, and is outputted on the Orbiter as a paper hard copy. Four modes of operation will be provided to minimize the time required to transmit less than full-resolution imagery. This paper discusses the considerations and complications leading to the four modes and associated resolution requirements. The paper also presents the design of the CCD array ground scanner and airborne CRT hardcopier.

Hoover, A. A.; Land, C. K.; Lipoma, P. C.

1978-01-01

317

Working With Orbits  

NSDL National Science Digital Library

This site offers two programs to illustrate how orbits work. The Orbital Elements calculator contains animations to see how the appearance of an orbit depends on the values of the orbital elements which include distance from the Sun, eccentricity, pericenter location and anomaly. This is available in two or three dimensions. The Solar System allows users to watch several planets in our Solar System simultaneously orbit the Sun. An additional object (asteroid or comet) is present and users change the orbital parameters to see what types of orbits are possible for this object.

Douglas Hamilton

318

Spectroscopic (FT-IR, FT-Raman and UV) investigation, NLO, NBO, molecular orbital and MESP analysis of 2-{2-[(2,6-dichlorophenyl)amino]phenyl}acetic acid  

NASA Astrophysics Data System (ADS)

In this work, FT-IR and FT-Raman spectra of 2-{2-[(2,6-dichlorophenyl)amino]phenyl}acetic acid (abbreviated as 2DCPAPAA) have been reported in the regions 4000-450 cm-1 and 4000-50 cm-1, respectively. The molecular structure, geometry optimization, intensities, vibrational frequencies were obtained by the ab initio and DFT levels of theory B3LYP with 6-311++G(d,p) standard basis set and a different scaling of the calculated wave numbers. The complete vibrational assignments were performed on the basis of the potential energy distribution (PED) of the vibrational modes calculated using vibrational energy distribution analysis (VEDA 4) program. The harmonic frequencies were calculated and the scaled values were compared with experimental FT-IR and FT-Raman data. The observed and the calculated frequencies are found to be in good agreement. Stability of the molecule arising from hyper conjugative interactions, charge delocalization has been analyzed using natural bond orbital (NBO) analysis. The thermodynamic properties of the title compound at different temperature reveal the correlations between standard heat capacities (C) standard entropies (S) standard enthalpy changes (?H). The important non-linear optical properties such as electric dipole momentum, polarizability and first hyperpolarizability of 2DCPAPAA have been computed using B3LYP/6-311++G(d,p) quantum chemical calculations. The Natural charges, HOMO, LUMO, chemical hardness (?), chemical potential (?), Electro negativity (?) and electrophilicity values (?) are calculated and reported. The oscillator's strength, wave length, and energy calculated by TD-DFT and 2DCPAPAA is approach complement with the experimental findings. The molecular electrostatic potential (MESP) surfaces of the molecule were constructed.

Govindasamy, P.; Gunasekaran, S.

2015-02-01

319

Spectroscopic (FT-IR, FT-Raman and UV) investigation, NLO, NBO, molecular orbital and MESP analysis of 2-{2-[(2,6-dichlorophenyl)amino]phenyl}acetic acid.  

PubMed

In this work, FT-IR and FT-Raman spectra of 2-{2-[(2,6-dichlorophenyl)amino]phenyl}acetic acid (abbreviated as 2DCPAPAA) have been reported in the regions 4000-450cm(-1) and 4000-50cm(-1), respectively. The molecular structure, geometry optimization, intensities, vibrational frequencies were obtained by the ab initio and DFT levels of theory B3LYP with 6-311++G(d,p) standard basis set and a different scaling of the calculated wave numbers. The complete vibrational assignments were performed on the basis of the potential energy distribution (PED) of the vibrational modes calculated using vibrational energy distribution analysis (VEDA 4) program. The harmonic frequencies were calculated and the scaled values were compared with experimental FT-IR and FT-Raman data. The observed and the calculated frequencies are found to be in good agreement. Stability of the molecule arising from hyper conjugative interactions, charge delocalization has been analyzed using natural bond orbital (NBO) analysis. The thermodynamic properties of the title compound at different temperature reveal the correlations between standard heat capacities (C) standard entropies (S) standard enthalpy changes (?H). The important non-linear optical properties such as electric dipole momentum, polarizability and first hyperpolarizability of 2DCPAPAA have been computed using B3LYP/6-311++G(d,p) quantum chemical calculations. The Natural charges, HOMO, LUMO, chemical hardness (?), chemical potential (?), Electro negativity (?) and electrophilicity values (?) are calculated and reported. The oscillator's strength, wave length, and energy calculated by TD-DFT and 2DCPAPAA is approach complement with the experimental findings. The molecular electrostatic potential (MESP) surfaces of the molecule were constructed. PMID:25459716

Govindasamy, P; Gunasekaran, S

2014-10-24

320

Orbital fractures: a review  

PubMed Central

This review of orbital fractures has three goals: 1) to understand the clinically relevant orbital anatomy with regard to periorbital trauma and orbital fractures, 2) to explain how to assess and examine a patient after periorbital trauma, and 3) to understand the medical and surgical management of orbital fractures. The article aims to summarize the evaluation and management of commonly encountered orbital fractures from the ophthalmologic perspective and to provide an overview for all practicing ophthalmologists and ophthalmologists in training. PMID:21339801

Joseph, Jeffrey M; Glavas, Ioannis P

2011-01-01

321

Theory of satellite orbit-orbit resonance  

NASA Technical Reports Server (NTRS)

On the basis of the strong mathematical and physical parallels between orbit-orbit and spin-orbit resonances, the dynamics of mutual orbit perturbations between two satellites about a massive planet are examined, exploiting an approach previously adopted in the study of spin-orbit coupling. Resonances are found to exist when the mean orbital periods are commensurable with respect to some rotating axis, which condition also involves the apsidal and nodal motions of both satellites. In any resonant state the satellites are effectively trapped in separate potential wells, and a single variable is found to describe the simultaneous librations of both satellites. The librations in longitude are 180 deg out-of-phase, with fixed amplitude ratio that depends only on their relative masses and semimajor axes. The theory is applicable to Saturn's resonant pairs Titan-Hyperion and Mimas-Tethys, and in these cases the calculated libration periods are in reasonably good agreement with the observed periods.

Blitzer, L.; Anderson, J. D.

1981-01-01

322

Quantum Monte Carlo and high-level ab initio molecular orbital investigation of dissociation channels of the positronic alkali-metal hydrides, [XH;e+] (X = Li, Na, and K)  

NASA Astrophysics Data System (ADS)

Energy thresholds for dissociation channels of positronic alkali-metal hydrides, [XH;e+] (X = Li, Na, and K), to XH + e+(positron dissociation), XH+ + Ps (positronium dissociation), and X+ + [H-;e+] (positronic hydride ion dissociation) have been calculated using quantum Monte Carlo and high-level ab initio molecular orbital methods, and including quantum zero-point vibrational energy of all of the particles. As the atomic number of X increases from Li to K, the dissociation energy to XH + e+ increases because the dipole moment of XH increases with the atomic number of X, while the dissociation energy to XH+ + Ps decreases. The energy threshold for the ionic dissociation to X+ + [H-;e+] is also reduced, and we obtain 0.975 (3) eV, 0.573 (12) eV, and 0.472 (19) eV for [LiH;e+], [NaH;e+], and [KH;e+], respectively, for this channel. Our results strongly support the conclusion that, among these three channels, the lowest energy dissociation for [XH;e+] is the pathway to X+ + [H-;e+], where X = Li, Na, and K.

Yamada, Yurika; Kita, Yukiumi; Tachikawa, Masanori; Towler, Mike D.; Needs, Richard J.

2014-03-01

323

Lunar Reconnaissance Orbiter Orbit Determination Accuracy Analysis  

NASA Technical Reports Server (NTRS)

Results from operational OD produced by the NASA Goddard Flight Dynamics Facility for the LRO nominal and extended mission are presented. During the LRO nominal mission, when LRO flew in a low circular orbit, orbit determination requirements were met nearly 100% of the time. When the extended mission began, LRO returned to a more elliptical frozen orbit where gravity and other modeling errors caused numerous violations of mission accuracy requirements. Prediction accuracy is particularly challenged during periods when LRO is in full-Sun. A series of improvements to LRO orbit determination are presented, including implementation of new lunar gravity models, improved spacecraft solar radiation pressure modeling using a dynamic multi-plate area model, a shorter orbit determination arc length, and a constrained plane method for estimation. The analysis presented in this paper shows that updated lunar gravity models improved accuracy in the frozen orbit, and a multiplate dynamic area model improves prediction accuracy during full-Sun orbit periods. Implementation of a 36-hour tracking data arc and plane constraints during edge-on orbit geometry also provide benefits. A comparison of the operational solutions to precision orbit determination solutions shows agreement on a 100- to 250-meter level in definitive accuracy.

Slojkowski, Steven E.

2014-01-01

324

Determination of cellulose crystallinity from powder diffraction diagrams.  

PubMed

One-dimensional (1D) (spherically averaged) powder diffraction diagrams are commonly used to determine the degree of cellulose crystallinity in biomass samples. Here, it is shown using molecular modeling how disorder in cellulose fibrils can lead to considerable uncertainty in conclusions drawn concerning crystallinity based on 1D powder diffraction data alone. For example, cellulose microfibrils that contain both crystalline and noncrystalline segments can lead to powder diffraction diagrams lacking identifiable peaks, while microfibrils without any crystalline segments can lead to such peaks. This leads to false positives, that is, assigning disordered cellulose as crystalline, and false negatives, that is, categorizing fibrils with crystalline segments as amorphous. The reliable determination of the fraction of crystallinity in any given biomass sample will require a more sophisticated approach combining detailed experiment and simulation. © 2014 Wiley Periodicals, Inc. Biopolymers 103: 67-73, 2015. PMID:25269646

Lindner, Benjamin; Petridis, Loukas; Langan, Paul; Smith, Jeremy C

2015-02-01

325

A layout algorithm for data flow diagrams  

SciTech Connect

A layout algorithm is presented that allows the automatic drawing of data flow diagrams, a diagrammatic representation widely used in the functional analysis of information systems. A grid standard is defined for such diagrams, and aesthetics for a good readability are identified. The layout algorithm receives as input an abstract graph, specifying connectivity relations between the elements of the diagram, and produces as output a corresponding diagram according to the aesthetics. The basic strategy is to build incrementally the layout; first, a good topology is constructed with few crossings between edges; subsequently, the shape of the diagram is determined in terms of angles appearing along edges; and finally, dimensions are given to the graph, obtaining a grid skeleton for the diagram.

Batini, C.; Nardelli, E.; Tamassia, R.

1986-04-01

326

Variable stars across the observational HR diagram  

Microsoft Academic Search

An overview of pulsating variable stars across the observational Hertzprung-Russel (HR) diagram is presented, together with a summary of their global properties. The HR diagram is presented with a third colour-coded dimension, visualizing the fraction of variable, the amplitude of variability or the period of variability. The distribution of variable stars in the other observational diagrams, such as the Period-Amplitude

Laurent Eyer; Nami Mowlavi

2008-01-01

327

Hubble's diagram and cosmic expansion  

PubMed Central

Edwin Hubble's classic article on the expanding universe appeared in PNAS in 1929 [Hubble, E. P. (1929) Proc. Natl. Acad. Sci. USA 15, 168–173]. The chief result, that a galaxy's distance is proportional to its redshift, is so well known and so deeply embedded into the language of astronomy through the Hubble diagram, the Hubble constant, Hubble's Law, and the Hubble time, that the article itself is rarely referenced. Even though Hubble's distances have a large systematic error, Hubble's velocities come chiefly from Vesto Melvin Slipher, and the interpretation in terms of the de Sitter effect is out of the mainstream of modern cosmology, this article opened the way to investigation of the expanding, evolving, and accelerating universe that engages today's burgeoning field of cosmology. PMID:14695886

Kirshner, Robert P.

2004-01-01

328

Phase diagrams for DNA crystallization systems.  

PubMed

Phase diagrams for several oligonucleotide duplex-spermine systems have been constructed. These diagrams characterize the duplex and spermine concentrations ranges in which crystalline precipitates are formed. All of them are wedge-like form. The slope of the upper branch of the diagram is determined by the oligonucleotide length. The position of the lower branch depends on both the nucleotide sequence and its length. The position of the lower branch depends on both the nucleotide sequence and its length. It has been shown that the addition to the system of MgCl2 and NaCl salts and MPD results in specific changes in the diagrams. A model for oligonucleotide duplex-spermine system has been suggested which explains the main characteristic features of the obtained phase diagrams. The experimental phase diagrams for the (pGpT)n (pApC)n-spermine system (n = 2,3,4) have been analyzed ion terms of this model and the values of the binding constants of spermine and Mg2+ ions binding to duplexes have been determined. It permitted to identify the complexes that precipitated in different regions of the phase diagrams under various conditions. The diagram obtained in the presence of a cobalt hexammine counterion is also considered. It has been shown that this phase diagram, in general, is similar to those obtained for the oligonucleotide duplex-spermine system. PMID:3271481

Malinina, L V; Makhaldiani, V V; Tereshko, V A; Zarytova, V F; Ivanova, E M

1987-10-01

329

Variable stars across the observational HR diagram  

E-print Network

An overview of pulsating variable stars across the observational Hertzprung-Russel (HR) diagram is presented, together with a summary of their global properties. The HR diagram is presented with a third colour-coded dimension, visualizing the fraction of variable, the amplitude of variability or the period of variability. The distribution of variable stars in the other observational diagrams, such as the Period-Amplitude diagram, is also presented. Some of the progresses performed in the field of variable stars during the last decade are briefly summarized, and future projects that will improve our knowledge of variable stars are mentioned.

Laurent Eyer; Nami Mowlavi

2007-12-21

330

Hofstadter Butterfly Diagram in Noncommutative Space  

E-print Network

We study an energy spectrum of electron moving under the constant magnetic field in two dimensional noncommutative space. It take place with the gauge invariant way. The Hofstadter butterfly diagram of the noncommutative space is calculated in terms of the lattice model which is derived by the Bopp's shift for space and by the Peierls substitution for external magnetic field. We also find the fractal structure in new diagram. Although the global features of the new diagram are similar to the diagram of the commutative space, the detail structure is different from it.

Hidenori Takahashi; Masanori Yamanaka

2006-06-23

331

Manned Venus Orbiting Mission  

NASA Technical Reports Server (NTRS)

Manned orbiting stopover round trips to Venus are studied for departure dates between 1975 and 1986 over a range of trip times and stay times. The use of highly elliptic parking orbits at Venus leads to low initial weights in Earth orbit compared with circular orbits. For the elliptic parking orbit, the effect of constraints on the low altitude observation time on the initial weight is shown. The mission can be accomplished with the Apollo level of chemical propulsion, but advanced chemical or nuclear propulsion can give large weight reductions. The Venus orbiting mission weights than the corresponding Mars mission.

Willis, E. A., Jr.

1967-01-01

332

Pilot-wave hydrodynamics in a rotating frame: Exotic orbits  

NASA Astrophysics Data System (ADS)

We present the results of a numerical investigation of droplets walking on a rotating vibrating fluid bath. The drop's trajectory is described by an integro-differential equation, which is simulated numerically in various parameter regimes. As the forcing acceleration is progressively increased, stable circular orbits give way to wobbling orbits, which are succeeded in turn by instabilities of the orbital center characterized by steady drifting then discrete leaping. In the limit of large vibrational forcing, the walker's trajectory becomes chaotic, but its statistical behavior reflects the influence of the unstable orbital solutions. The study results in a complete regime diagram that summarizes the dependence of the walker's behavior on the system parameters. Our predictions compare favorably to the experimental observations of Harris and Bush ["Droplets walking in a rotating frame: from quantized orbits to multimodal statistics," J. Fluid Mech. 739, 444-464 (2014)].

Oza, Anand U.; Wind-Willassen, Øistein; Harris, Daniel M.; Rosales, Rodolfo R.; Bush, John W. M.

2014-08-01

333

Enthalpies of Formation of Gas-Phase N3, N3-, N5+, and N5- from Ab Initio Molecular Orbital Theory, Stability Predictions for N5+N3- and N5+N5-, and Experimental Evidence for the Instability of N5+N3-  

Microsoft Academic Search

Ab initio molecular orbital theory has been used to calculate accurate enthalpies of formation and adiabatic electron affinities or ionization potentials for N3, N3-, N5+, and N5- from total atomization energies. Born-Haber cycle calculations, using estimated lattice energies and the adiabatic ionization potentials of the anions and electron affinities of the cations, permit for the first time reliable stability predictions

David A. Dixon; David F. Feller; Karl O. Christe; william W. wilson; Ashwani vij; vandana vij; H. Donald Brooke Jenkins; ryan M. olson; Mark S. Gordon

2004-01-01

334

Lunar orbiting prospector  

NASA Technical Reports Server (NTRS)

One of the prime reasons for establishing a manned lunar presence is the possibility of using the potential lunar resources. The Lunar Orbital Prospector (LOP) is a lunar orbiting platform whose mission is to prospect and explore the Moon from orbit in support of early lunar colonization and exploitation efforts. The LOP mission is divided into three primary phases: transport from Earth to low lunar orbit (LLO), operation in lunar orbit, and platform servicing in lunar orbit. The platform alters its orbit to obtain the desired surface viewing, and the orbit can be changed periodically as needed. After completion of the inital remote sensing mission, more ambitious and/or complicated prospecting and exploration missions can be contemplated. A refueled propulsion module, updated instruments, or additional remote sensing packages can be flown up from the lunar base to the platform.

1988-01-01

335

Orbiting Binary Stars  

NSDL National Science Digital Library

This simulation demonstrates the path of binary stars' orbit. The user is able to set the masses, orbital separation, orbital eccentricity, the inclination angle to our line of sight, and the angle of the nodes of two orbiting stars. The observed velocities of the two stars, and the Doppler shifted spectral lines are also shown in the upper right box. The site also includes definitions of terms used, instructions on how to use the simulation and a few examples.

Kolena, John

2007-12-11

336

On hooks of skew Young diagrams and bars in shifted diagrams  

E-print Network

1 On hooks of skew Young diagrams and bars in shifted diagrams Christine Bessenrodt Fakultat f;ectiveness of the methods introduced in [1] we investi- gate hooks in skew Young diagrams and bars in shifted combinatorial proofs for re#12;ned identities on multisets of hooks in the case of shift-symmetric partitions. 1

Bessenrodt, Christine

337

Phase diagram and excitations of a Shiba molecule  

NASA Astrophysics Data System (ADS)

We analyze the phase diagram associated with a pair of magnetic impurities trapped in a superconducting host. The natural interplay between Kondo screening, superconductivity, and exchange interactions leads to a rich array of competing phases, whose transitions are characterized by discontinuous changes of the total spin. Our analysis is based on a combination of numerical renormalization group techniques as well as semiclassical analytics. In addition to the expected screened and unscreened phases, we observe a new molecular doublet phase where the impurity spins are only partially screened by a single extended quasiparticle. Direct signatures of the various Shiba molecule states can be observed via radio-frequency spectroscopy.

Yao, N. Y.; Moca, C. P.; Weymann, I.; Sau, J. D.; Lukin, M. D.; Demler, E. A.; Zaránd, G.

2014-12-01

338

Hydatid cyst of orbit.  

PubMed

A 40-year-old woman presented with protrusion and diminution of vision of left eye for 3 months. CT scan of orbit revealed an intra-orbital cystic space occupying lesion. Exenteration of the left orbit was done and histopathological examination of the cystic mass proved it to be a case of hydatid cyst. PMID:22480108

Bhaduri, Gautam; Chatterjee, Soumya Swarup; Gayen, Sharmistha; Goswami, Soumik

2011-09-01

339

Five Equivalent d Orbitals  

ERIC Educational Resources Information Center

Amplifies and clarifies a previous paper on pyramidal d orbitals. Discusses two sets of pyramid d orbitals with respect to their maximum bond strength and their symmetry. Authors described the oblate and prolate pentagonal antiprisms arising from the two sets of five equivalent d orbitals. (RR)

Pauling, Linus; McClure, Vance

1970-01-01

340

Mars Reconnaissance Orbiter  

NSDL National Science Digital Library

This is the mission web site for the Mars Reconnaissance Orbiter, which went into orbit around Mars on March 10, 2006. The site provides links to updates and information about the project. The site features links to Mars Reconnaissance Orbiter images, animations, and datasets. Science operations commence in November, 2006.

Laboratory, Jet P.; Administration, National A.

341

SEASAT B orbit synthesis  

NASA Technical Reports Server (NTRS)

Addition were made to Battelle's Interactive Graphics Orbit Selection (IGOS) program; IGOS was exercised via telephone lines from JPL, and candidate SEASAT orbits were analyzed by Battelle. The additions to the program enable clear understanding of the implications of a specific orbit to the diverse desires of the SEASAT user community.

Rea, F. G.; Warmke, J. M.

1976-01-01

342

Bound central orbits  

NASA Astrophysics Data System (ADS)

The orbits in any central potential are described analytically and new expressions are derived for their periods and precession rates. A simple perturbation theory allows their delineation to any accuracy. Kepler's equation is generalized to such orbits and angle and action variables are given for them. A new property of orbits under inverse fifth power forces is found.

Lynden-Bell, D.

2015-02-01

343

Multidimensional Modeling with UML Package Diagrams  

Microsoft Academic Search

The Unified Modeling Language (UML) has become the defacto standard for object-oriented analysis and design, providing differentdiagrams for modeling different aspects of a system. In this paper, wepresent the development of multidimensional (MD) models for data warehouses(DW) using UML package diagrams. In this way, when modelingcomplex and large DW systems, we are not restricted to use fiat UMLclass diagrams. We

Sergio Luján-mora; Juan Trujillo; Il-yeol Song

2002-01-01

344

Projections in Venn-Euler Diagrams  

Microsoft Academic Search

Venn diagrams and Euler circles have long been used to express constraints on sets and their relationships with other sets. However, these notations can get very cluttered when we consider many closed curves or contours. In order to reduce this clutter, and to focus attention within the diagram appropriately, the notion of a projected contour, or projection, is introduced. Informally,

Joseph Gil; John Howse; Stuart Kent; John Taylor

2000-01-01

345

THE QCD PHASE DIAGRAM AT FINITE DENSITY.  

SciTech Connect

We study the density of states method to explore the phase diagram of the chiral transition on the temperature and quark chemical potential plane. Four quark flavours are used in the analysis. Though the method is quite expensive small lattices show an indication for a triple-point connecting three different phases on the phase diagram.

SCHMIDT, C.; FODOR, Z.; KATZ, S.

2005-07-25

346

Shear and Moment Diagrams with a Microcomputer.  

ERIC Educational Resources Information Center

Describes an Applesoft computer program which determines the shear and moment diagrams for any combination of four different load configurations on a simply supported beam. Examples of different load configurations and the diagrams produced are included. Also included is the program listing. (JN)

Wallace, John S.

1984-01-01

347

Myopic Value of Information in Influence Diagrams  

Microsoft Academic Search

We present a method for calculation of myopicvalue of information in influence diagrams(Howard & Matheson, 1981) based onthe strong junction tree framework (Jensenet al., 1994) .An influence diagram specifies a certain orderof observations and decisions through itsstructure. This order is reflected in the correspondingjunction trees by the order in whichthe nodes are marginalized. This order ofmarginalization can be changed by

Søren L. Dittmer; Finn Verner Jensen

1997-01-01

348

Phase Diagrams for Traffics on the Crossroad  

NASA Astrophysics Data System (ADS)

The traffic flows on two one-lane roads, crossing at a point, are studied on the basis of the local occupation probability method. The phase diagrams are constructed for the cases of various maximum car velocities. It has turned out that the phase diagrams consist essentailly of five regions.

Ishibashi, Yoshihiro; Fukui, Minoru

2001-09-01

349

The QCD phase diagram at finite density  

E-print Network

We study the density of states method to explore the phase diagram of the chiral transition on the tempeature and quark chemical potential plane. Four quark flavours are used in the analysis. Though the method is quite expensive small lattices show an indication for a triple-point connecting three different phases on the phase diagram.

Christian Schmidt; Zoltan Fodor; Sandor Katz

2005-10-18

350

Resummation of Cactus Diagrams in Lattice QCD  

E-print Network

We show how to perform a resummation, to all orders in perturbation theory, of a certain class of gauge invariant diagrams in Lattice QCD. These diagrams are often largely responsible for lattice artifacts. Our resummation leads to an improved perturbative expansion. Applied to a number of cases of interest, this expansion yields results remarkably close to corresponding nonperturbative estimates.

H. Panagopoulos; E. Vicari

1998-06-08

351

Structural and electronic properties of Si n, Si n+, and AlSi n-1 (n=2-13) clusters: theoretical investigation based on ab initio molecular orbital theory.  

PubMed

The geometric and electronic structures of Si(n), Si(n) (+), and AlSi(n-1) clusters (2< or =n< or =13) have been investigated using the ab initio molecular orbital theory under the density functional theory formalism. The hybrid exchange-correlation energy function (B3LYP) and a standard split-valence basis set with polarization functions [6-31G(d)] were employed for this purpose. Relative stabilities of these clusters have been analyzed based on their binding energies, second difference in energy (Delta (2)E) and fragmentation behavior. The equilibrium geometry of the neutral and charged Si(n) clusters show similar structural growth. However, significant differences have been observed in the electronic structure leading to their different stability pattern. While for neutral clusters, the Si(10) is magic, the extra stability of the Si(11) (+) cluster over the Si(10) (+) and Si(12) (+) bears evidence for the magic behavior of the Si(11) (+) cluster, which is in excellent agreement with the recent experimental observations. Similarly for AlSi(n-1) clusters, which is isoelectronic with Si(n) (+) clusters show extra stability of the AlSi(10) cluster suggesting the influence of the electronic structures for different stabilities between neutral and charged clusters. The ground state geometries of the AlSi(n-1) clusters show that the impurity Al atom prefers to substitute for the Si atom, that has the highest coordination number in the host Si(n) cluster. The fragmentation behavior of all these clusters show that while small clusters prefers to evaporate monomer, the larger ones dissociate into two stable clusters of smaller size. PMID:15485237

Nigam, Sandeep; Majumder, Chiranjib; Kulshreshtha, S K

2004-10-22

352

HertzsprungâRussell (H-R) Diagrams  

NSDL National Science Digital Library

The HertzsprungâRussell (H-R) Diagrams model simulates HertzsprungâRussell (HR or H-R) diagram for groups of stars. The diagram is a scatter plot of steller luminosity vs. stellar temperature. The luminosity of stars is proportional to the star's radius squared and its temperature to the fourth power, and for Main Sequence stars, their luminosity is also proportional to their mass to the 3.5 power. Since the range of stellar luminosities and stellar temperatures is so large, the plot uses a log-log scale. The diagram is a way to understand stellar evolution. The HR diagram shows nearby stars, bright stars, and a user-defined star. One can also show the blackbody radiation curve and the user-defined star. The radius of the user-defined star (in Rsun) and the temperature of the user-defined star in Kelvin (5780 K is Tsun) can be changed.

Belloni, Mario

2010-11-11

353

Global petrologic variations on the moon - A ternary-diagram approach  

NASA Technical Reports Server (NTRS)

An improved method for global petrologic mapping of the moon is presented, which uses a color-coded ternary diagram whose apexes are assigned the average Fe and Th/Ti ratio (normalized to chondrites) compositions of KREEP/Mg-suite rocks, mare basalts, and ferroan anorthosites. The composition of each pixel within these Apollo orbital gamma ray data bases is used to determine its position within the ternary diagram. The color corresponding to this ternary position is then placed on a classification map at that pixel's position within the orbital data bases. The resultant classification map shows spatial transitions among petrologic units, allows direct determination of the relative proportions of each end-member composition in a pixel, and provides more geologic information than can be obtained by using only the elemental data. The map units correspond remarkably well to previously delineated geologic provinces.

Davis, Philip A.; Spudis, Paul D.

1987-01-01

354

Phase diagram of a reentrant gel of patchy particles  

SciTech Connect

We study the phase diagram of a binary mixture of patchy particles which has been designed to form a reversible gel. For this we perform Monte Carlo and molecular dynamics simulations to investigate the thermodynamics of such a system and compare our numerical results with predictions based on the analytical parameter-free Wertheim theory. We explore a wide range of the temperature-density-composition space that defines the three-dimensional phase diagram of the system. As a result, we delimit the region of thermodynamic stability of the fluid. We find that for a large region of the phase diagram the Wertheim theory is able to give a quantitative description of the system. For higher densities, our simulations show that the system is crystallizing into a BCC structure. Finally, we study the relaxation dynamics of the system by means of the density and temperature dependences of the diffusion coefficient. We show that there exists a density range where the system passes reversibly from a gel to a fluid upon both heating and cooling, encountering neither demixing nor phase separation.

Roldán-Vargas, Sándalo; Smallenburg, Frank; Sciortino, Francesco [Department of Physics, Sapienza, Università di Roma, Piazzale Aldo Moro 2, I-00185 Roma (Italy)] [Department of Physics, Sapienza, Università di Roma, Piazzale Aldo Moro 2, I-00185 Roma (Italy); Kob, Walter [Laboratoire Charles Coulomb, UMR 5221, CNRS and Université Montpellier 2, 34095 Montpellier (France)] [Laboratoire Charles Coulomb, UMR 5221, CNRS and Université Montpellier 2, 34095 Montpellier (France)

2013-12-28

355

Phase diagram of ammonium nitrate  

SciTech Connect

Ammonium Nitrate (AN) is a fertilizer, yet becomes an explosive upon a small addition of chemical impurities. The origin of enhanced chemical sensitivity in impure AN (or AN mixtures) is not well understood, posing significant safety issues in using AN even today. To remedy the situation, we have carried out an extensive study to investigate the phase stability of AN and its mixtures with hexane (ANFO–AN mixed with fuel oil) and Aluminum (Ammonal) at high pressures and temperatures, using diamond anvil cells (DAC) and micro-Raman spectroscopy. The results indicate that pure AN decomposes to N{sub 2}, N{sub 2}O, and H{sub 2}O at the onset of the melt, whereas the mixtures, ANFO and Ammonal, decompose at substantially lower temperatures. The present results also confirm the recently proposed phase IV-IV{sup ?} transition above 17 GPa and provide new constraints for the melting and phase diagram of AN to 40 GPa and 400°C.

Dunuwille, Mihindra; Yoo, Choong-Shik, E-mail: csyoo@wsu.edu [Department of Chemistry and Institute for Shock Physics, Washington State University, Pullman, Washington 99164 (United States)] [Department of Chemistry and Institute for Shock Physics, Washington State University, Pullman, Washington 99164 (United States)

2013-12-07

356

Orbits in Space  

NSDL National Science Digital Library

This discussion of orbits around the Earth and Sun begins by describing synchronous orbits and then explains how satellites in low orbits encounter atmospheric interference. There is an explanation of how the bulge of the Earth affects the calculation of an Earth orbit. The satellites stationed at the Lagrangian Point L1, ACE and SOHO are discussed along with information on the other Lagrangian points. Finally, there is information about other orbits within our solar system and an explanation of why it is no easy task to get to the Sun.

David Stern

357

Orbital Evolution of Asteroids  

NASA Astrophysics Data System (ADS)

The synthetic orbital frequencies and eccentricities of main belt asteroids computed by Knezevic and Milani [2] show evidence that the structure of the asteroid belt has been determined by a dense of web of high-order resonances. By examining the orbital frequency distribution at high resolution, we discover a correlation between asteroid number density, mean orbital eccentricity and Lyapunov Characteristic Exponent. In particular, the orbital eccentricities of asteroids trapped in resonance tend to be higher than those of non-resonant asteroids and we argue that this is observational evidence for orbital evolution due to chaotic diffusion.

Dermott, S. F.; Kehoe, T. J. J.

2011-10-01

358

Orbit Software Suite  

NASA Technical Reports Server (NTRS)

Orbit Software Suite is used to support a variety of NASA/DM (Dependable Multiprocessor) mission planning and analysis activities on the IPS (Intrusion Prevention System) platform. The suite of Orbit software tools (Orbit Design and Orbit Dynamics) resides on IPS/Linux workstations, and is used to perform mission design and analysis tasks corresponding to trajectory/ launch window, rendezvous, and proximity operations flight segments. A list of tools in Orbit Software Suite represents tool versions established during/after the Equipment Rehost-3 Project.

Osgood, Cathy; Williams, Kevin; Gentry, Philip; Brownfield, Dana; Hallstrom, John; Stuit, Tim

2012-01-01

359

Environmental dynamics at orbital altitudes  

NASA Technical Reports Server (NTRS)

The work reported involved the improvement of aerodynamic theory for free molecular and transition flow regimes. The improved theory was applied to interpretation of the dynamic response of objects traveling through the atmosphere. Satellite drag analysis includes analysis methods, atmospheric super rotation effects, and satellite lift effects on orbital dynamics. Transition flow regimes were studied with falling sphere data and errors resulting in inferred atmospheric parameters from falling sphere techniques. Improved drag coefficients reveal considerable error in previous falling sphere data. The drag coefficient has been studied for the entire spectrum of Knudsen Number and speed ratio, with particular emphasis on the theory of the very low-speed ratio regime.

Karr, G. R.

1976-01-01

360

Lunar Reconnaissance Orbiter Orbit Determination Accuracy Analysis  

NASA Technical Reports Server (NTRS)

LRO definitive and predictive accuracy requirements were easily met in the nominal mission orbit, using the LP150Q lunar gravity model. center dot Accuracy of the LP150Q model is poorer in the extended mission elliptical orbit. center dot Later lunar gravity models, in particular GSFC-GRAIL-270, improve OD accuracy in the extended mission. center dot Implementation of a constrained plane when the orbit is within 45 degrees of the Earth-Moon line improves cross-track accuracy. center dot Prediction accuracy is still challenged during full-Sun periods due to coarse spacecraft area modeling - Implementation of a multi-plate area model with definitive attitude input can eliminate prediction violations. - The FDF is evaluating using analytic and predicted attitude modeling to improve full-Sun prediction accuracy. center dot Comparison of FDF ephemeris file to high-precision ephemeris files provides gross confirmation that overlap compares properly assess orbit accuracy.

Slojkowski, Steven E.

2014-01-01

361

Transneptunian orbit computation Jenni Virtanen  

E-print Network

Transneptunian orbit computation Jenni Virtanen Finnish Geodetic Institute Gonzalo Tancredi Observatory Karri Muinonen University of Helsinki We review the orbit computation problem orbital arcs, which are known to be coupled with large uncertainties in orbital elements. Currently

Bernstein, Gary

362

6 Semiempirical Molecular Orbital Study of  

E-print Network

discharge techniques [2], catalytic chemical vapor deposition (CCVD) methods [3­6,7­10] have been widely, such as the high-pressure carbon mon- oxide method [7], floating catalysts were used during the CVD process [10,14]. It is well known that the catalytic metals are essen- tial for synthesis of single-wall CNTs

Elliott, James

363

The Amplituhedron from Momentum Twistor Diagrams  

E-print Network

We propose a new diagrammatic formulation of the all-loop scattering amplitudes/Wilson loops in planar N=4 SYM, dubbed the "momentum-twistor diagrams". These are on-shell-diagrams obtained by gluing trivalent black and white vertices defined in momentum twistor space, which, in the reduced diagram case, are known to be related to diagrams in the original twistor space. The new diagrams are manifestly Yangian invariant, and they naturally represent factorization and forward-limit contributions in the all-loop BCFW recursion relations in momentum twistor space, in a fashion that is completely different from those in momentum space. We show how to construct and evaluate momentum-twistor diagrams, and how to use them to obtain tree-level amplitudes and loop-level integrands; in particular for the latter we identify an isolated bubble-structure for each loop variable, arising from a forward limit, or entangled removal of particles. From a given diagram one can directly read off the C, D matrices via a generalized "boundary measurement"; this in turn determines a cell in the amplituhedron associated with the amplitude, and our diagrammatic representations of the amplitude can provide triangulations of the amplituhedron with generally very intricate geometries. To demonstrate the computational power of the formalism, we give explicit results for general two-loop integrands, and the cells of the complete amplituhedron for two-loop MHV amplitudes.

Yuntao Bai; Song He

2014-08-11

364

The spin-polarized extended Brueckner orbitals  

NASA Astrophysics Data System (ADS)

Conventional natural and Brueckner orbitals (BOs) are rather frequently used for improving active orbital spaces in various configuration interaction (CI) approaches. However, the natural and Brueckner single-determinant models per se fail to give an adequate picture of highly correlated and quasidegenerate states such as open-shell singlet and dissociative states. We suggest the use of the spin-polarized extended BOs formally defining them in the same manner as in Löwdin's spin-extended Hartree-Fock method. Such BO orbitals turn out to be quite flexible and particularly useful for analyzing highly correlated electronic states. It is shown that the extended BOs always exist, unlike the usual unrestricted BOs. We discuss difficulties related to violation of size-consistency for spin projected determinant models. The working algorithm is proposed for computing BOs within the full CI and related complete active space methodology. The extended BOs are analyzed in terms of the special density-like matrices associated with spin-up and spin-down BO orbitals. From these density matrices, the corresponding spin-polarization diagrams are produced for effectively unpaired (essentially correlated) electrons. We illustrate the approach by calculations on cyclic hydrogen clusters (H4, H6, and H8), certain carbene diradicals and monoradicals, and low-lying excited states. The computations show that the BO spin-projected determinant provides a strong overlap with the multi-configurational state even for quasidegenerate states and bond breaking processes.

Luzanov, A. V.; Prezhdo, O. V.

2011-09-01

365

CUDD: CU Decision Diagram Package Release 2.2.0  

Microsoft Academic Search

The CUDD package provides functions to manipulate Binary Decision Diagrams (BDDs) [5,3], Algebraic Decision Diagrams (ADDs) [1], and Zero suppressed Decision Diagrams (ZDDs) [12]. BDDs are used to represent switch functions

Fabio Somenzi

1998-01-01

366

Orbital Debris Engineering Model (ORDEM) v.3  

NASA Technical Reports Server (NTRS)

A model of the manmade orbital debris environment is required by spacecraft designers, mission planners, and others in order to understand and mitigate the effects of the environment on their spacecraft or systems. A manmade environment is dynamic, and can be altered significantly by intent (e.g., the Chinese anti-satellite weapon test of January 2007) or accident (e.g., the collision of Iridium 33 and Cosmos 2251 spacecraft in February 2009). Engineering models are used to portray the manmade debris environment in Earth orbit. The availability of new sensor and in situ data, the re-analysis of older data, and the development of new analytical and statistical techniques has enabled the construction of this more comprehensive and sophisticated model. The primary output of this model is the flux [#debris/area/time] as a function of debris size and year. ORDEM may be operated in spacecraft mode or telescope mode. In the former case, an analyst defines an orbit for a spacecraft and "flies" the spacecraft through the orbital debris environment. In the latter case, an analyst defines a ground-based sensor (telescope or radar) in terms of latitude, azimuth, and elevation, and the model provides the number of orbital debris traversing the sensor's field of view. An upgraded graphical user interface (GUI) is integrated with the software. This upgraded GUI uses project-oriented organization and provides the user with graphical representations of numerous output data products. These range from the conventional flux as a function of debris size for chosen analysis orbits (or views), for example, to the more complex color-contoured two-dimensional (2D) directional flux diagrams in local spacecraft elevation and azimuth.

Matney, Mark; Krisko, Paula; Xu, Yu-Lin; Horstman, Matthew

2013-01-01

367

Hooke, orbital motion, and Newton's Principia  

NASA Astrophysics Data System (ADS)

A detailed analysis is given of a 1685 graphical construction by Robert Hooke for the polygonal path of a body moving in a periodically pulsed radial field of force. In this example the force varies linearly with the distance from the center. Hooke's method is based directly on his original idea from the mid-1660s that the orbital motion of a planet is determined by compounding its tangential velocity with a radial velocity impressed by the gravitational attraction of the sun at the center. This hypothesis corresponds to the second law of motion, as formulated two decades later by Newton, and its geometrical implementation constitutes the cornerstone of Newton's Principia. Hooke's diagram represents the first known accurate graphical evaluation of an orbit in a central field of force, and it gives evidence that he demonstrated that his resulting discrete orbit is an approximate ellipse centered at the origin of the field of force. A comparable calculation to obtain orbits for an inverse square force, which Hooke had conjectured to be the gravitational force, has not been found among his unpublished papers. Such a calculation is carried out here numerically with the Newton-Hooke geometrical construction. It is shown that for orbits of comparable or larger eccentricity than Hooke's example, a graphical approach runs into convergence difficulties due to the singularity of the gravitational force at the origin. This may help resolve the long-standing mystery why Hooke never published his controversial claim that he had demonstrated that an attractive force, which is ``...in a duplicate proportion to the Distance from the Center Reciprocall...'' implies elliptic orbits.

Nauenberg, Michael

1994-04-01

368

Frustration and Entanglement in Compass and Spin-Orbital Models  

E-print Network

We review the consequences of intrinsic frustration of the orbital superexchange and of spin-orbital entanglement. While Heisenberg perturbing interactions remove frustration in the compass model, the lowest columnar excitations are robust in the nanoscopic compass clusters and might be used for quantum computations. Entangled spin-orbital states determine the ground states in some cases, while in others concern excited states and lead to measurable consequences, as in the $R$VO$_3$ perovskites. On-site entanglement for strong spin-orbit coupling generates the frustrated Kitaev-Heisenberg model with a rich magnetic phase diagram on the honeycomb lattice. Frustration is here reflected in hole propagation which changes from coherent in an antiferromagnet via hidden quasiparticles in zigzag and stripe phases to entirely incoherent one in the Kitaev spin liquid.

Andrzej M. Ole?

2014-10-24

369

Asymmetric Orbital-Lattice Interactions in Ultrathin Correlated Oxide Films  

NASA Astrophysics Data System (ADS)

Epitaxial control of strongly correlated electrons offers opportunities to push beyond the bulk phase diagram and access new ground states. Using resonant x-ray spectroscopies combined with density functional calculations, we report the discovery of an asymmetric biaxial strain-induced 3d-orbital response in ultrathin films of the correlated metal LaNiO3 that are not accessible in the bulk [J. Chakhalian et al., PRL, 107, 116805 (2011)]. Compressive strain results in an orbital polarization due to structural induced changes in the crystal field, but tensile strain shows no orbital response. This is accompanied by a strong change in the oxygen hole states due a systematic change of the charge transfer energy as a function of strain. We suggest that knowledge of this asymmetric orbital-lattice interaction is fundamental to the rational design of quantum materials with exotic correlated phases and enhanced critical temperatures.

Chakhalian, Jak

2012-02-01

370

Orbit Determination of the Lunar Reconnaissance Orbiter  

NASA Technical Reports Server (NTRS)

We present the results on precision orbit determination from the radio science investigation of the Lunar Reconnaissance Orbiter (LRO) spacecraft. We describe the data, modeling and methods used to achieve position knowledge several times better than the required 50-100m (in total position), over the period from 13 July 2009 to 31 January 2011. In addition to the near-continuous radiometric tracking data, we include altimetric data from the Lunar Orbiter Laser Altimeter (LOLA) in the form of crossover measurements, and show that they strongly improve the accuracy of the orbit reconstruction (total position overlap differences decrease from approx.70m to approx.23 m). To refine the spacecraft trajectory further, we develop a lunar gravity field by combining the newly acquired LRO data with the historical data. The reprocessing of the spacecraft trajectory with that model shows significantly increased accuracy (approx.20m with only the radiometric data, and approx.14m with the addition of the altimetric crossovers). LOLA topographic maps and calibration data from the Lunar Reconnaissance Orbiter Camera were used to supplement the results of the overlap analysis and demonstrate the trajectory accuracy.

Mazarico, Erwan; Rowlands, D. D.; Neumann, G. A.; Smith, D. E.; Torrence, M. H.; Lemoine, F. G.; Zuber, M. T.

2011-01-01

371

Satellite orbit determination  

NASA Technical Reports Server (NTRS)

A historic account of the activities of the Satellite OD Group during the MM'71 mission is given along with an assessment of the accuracy of the determined orbit of the Mariner 9 spacecraft. Preflight study results are reviewed, and the major error sources described. Tracking and data fitting strategy actually used in the real time operations is itemized, and Deep Space Network data available for orbit fitting during the mission and the auxiliary information used by the navigation team are described. A detailed orbit fitting history of the first four revolutions of the satellite orbit of Mariner 9 is presented, with emphasis on the convergence problems and the delivered solution for the first orbit trim maneuver. Also included are a solution accuracy summary, the history of the spacecraft orbit osculating elements, the results of verifying the radio solutions with TV imaging data, and a summary of the normal points generated for the relativity experiment.

Jordan, J. F.; Boggs, D. H.; Born, G. H.; Christensen, E. J.; Ferrari, A. J.; Green, D. W.; Hylkema, R. K.; Mohan, S. N.; Reinbold, S. J.; Sievers, G. L.

1973-01-01

372

An Improved Mnemonic Diagram for Thermodynamic Relationships.  

ERIC Educational Resources Information Center

Considers pressure, volume, entropy, temperature, Helmholtz free energy, Gibbs free energy, enthalpy, and internal energy. Suggests the mnemonic diagram is for use with simple systems that are defined as macroscopically homogeneous, isotropic, uncharged, and chemically inert. (MVL)

Rodriguez, Joaquin; Brainard, Alan J.

1989-01-01

373

Sloan Digital Sky Survey - Hubble Diagram  

NSDL National Science Digital Library

This website, containing information from the Sloan Digital Sky Survey, provides projects and activities for advanced astronomy students. In this particular one, the user retraces Edwin Hubble's steps to discover that the Universe is expanding, by making a Hubble Diagram.

2010-01-07

374

A Smart Thermal Block Diagram Tool  

NASA Technical Reports Server (NTRS)

The presentation describes a Smart Thermal Block Diagram Tool. It is used by JPL's Team X in studying missions during the Pre-Phase A. It helps generate cost and mass estimates using proprietary data bases.

Tsuyuki, Glenn; Miyake, Robert; Dodge, Kyle

2008-01-01

375

The Art of Free-Body Diagrams.  

ERIC Educational Resources Information Center

Discusses the difficulty of drawing free-body diagrams which only show forces exerted on a body from its neighbors. Presents three ways a body may be modeled: a particle, rigid extended, and nonrigid extended. (MKR)

Puri, Avinash

1996-01-01

376

Pharmaceutical salt formation guided by phase diagrams.  

E-print Network

??Salt formation is frequently employed to improve the solubility and bioavailability of pharmaceutical compounds. Solid-Liquid-Equilibrium (SLE) phase diagram that serves as the foundation for designing… (more)

Lam, Ka Wing

2009-01-01

377

Voronoi diagram generation on the ellipsoidal earth  

NASA Astrophysics Data System (ADS)

Voronoi diagram on the earth surface is a powerful tool to study spatial proximity at continental or global scale. However, its computation remains challenging because geospatial features have complex shapes. This paper presents a raster-based algorithm to generate Voronoi diagrams on earth's surface. The algorithm approximates the exact point-to-point geographical distances using the cell-to-cell geographical distances calculated by a geographical distance transform. The result is a distance image on which Voronoi diagram is delineated. Compared to existing methods, the proposed algorithm calculates geographical distances based on an earth ellipsoid and allows Voronoi generators to take complex shapes. Most importantly, its approximation error is bounded thus enabling users to control the accuracy of the Voronoi diagram through grid resolution.

Hu, Hai; Liu, XiaoHang; Hu, Peng

2014-12-01

378

Architecture flow diagrams under teamwork reg sign  

SciTech Connect

The Teamwork CASE tool allows Data Flow Diagrams (DFDs) to be maintained for structured analysis. Fermilab has extended teamwork under UNIX{trademark} to permit Hatley and Pirbhai Architecture Flow Diagrams (AFDs) to be associated with DFDs and subsequently maintained. This extension, called TWKAFD, allows a user to open an AFD, graphically edit it, and replace it into a TWKAFD maintained library. Other aspects of Hatley and Pirbhai's methodology are supported. This paper presents a quick tutorial on Architecture Diagrams. It then describes the user's view of TWKAFD, the experience incorporating it into teamwork, and the successes with using the Architecture Diagram methodology along with the shortcomings of using the teamwork/TWKAFD tool. 8 refs.

Nicinski, T.

1992-02-01

379

Orbital myositis complicating sinusitis  

PubMed Central

Orbital myositis is a common cause of extraocular muscle enlargement. It is characterized by nonspecific inflammation of one or more extraocular muscles. Although often idiopathic in origin, orbital myositis has been associated with various noninfectious diseases. Several cases have also been reported as occurring after upper respiratory tract infections. The present report describes a case of orbital myositis together with subclinical sinusitis and its rapid resolution after antibiotic treatment. The literature on this clinical entity is also reviewed. PMID:18159317

Dylewski, Joe S; Drummond, Robert; Townsend, Tiffany

2001-01-01

380

Algebraic decision diagrams and their applications  

Microsoft Academic Search

In this paper we present theory and experiments on the AlgebraicDecision Diagrams (ADD's). These diagrams extend BDD'sby allowing values from an arbitrary finite domain to be associatedwith the terminal nodes. We present a treatment foundedin boolean algebras and discuss algorithms and results in applicationslike matrix multiplication and shortest path algorithms.Furthermore, we outline possible applications of ADD's to logicsynthesis, formal verification,

R. Iris Bahar; Erica A. Frohm; Charles M. Gaona; Gary D. Hachtel; Enrico Macii; Abelardo Pardo; Fabio Somenzi

1993-01-01

381

Implications of Cladistics: Understanding Branching Diagrams  

NSDL National Science Digital Library

This site explains how a cladogram is formed and its implications. The cladogram is compared to a family tree, however unlike family trees, ancestors in cladistics ideally give rise to only two descendent species. Also unlike family trees, new species form from splitting of old species. Three possible diagrams showing the relationship between humans, gorillas, baboons, and chimpanzees are demonstrated. The author explains why one diagram is favored and also explains the meaning of nodes and clades.

382

Elementary diagrams in nuclear and neutron matter  

SciTech Connect

Variational calculations of nuclear and neutron matter are currently performed using a diagrammatic cluster expansion with the aid of nonlinear integral equations for evaluating expectation values. These are the Fermi hypernetted chain (FHNC) and single-operator chain (SOC) equations, which are a way of doing partial diagram summations to infinite order. A more complete summation can be made by adding elementary diagrams to the procedure. The simplest elementary diagrams appear at the four-body cluster level; there is one such E{sub 4} diagram in Bose systems, but 35 diagrams in Fermi systems, which gives a level of approximation called FHNC/4. We developed a novel technique for evaluating these diagrams, by computing and storing 6 three-point functions, S{sub xyz}(r{sub 12}, r{sub 13}, r{sub 23}), where xyz (= ccd, cce, ddd, dde, dee, or eee) denotes the exchange character at the vertices 1, 2, and 3. All 35 Fermi E{sub 4} diagrams can be constructed from these 6 functions and other two-point functions that are already calculated. The elementary diagrams are known to be important in some systems like liquid {sup 3}He. We expect them to be small in nuclear matter at normal density, but they might become significant at higher densities appropriate for neutron star calculations. This year we programmed the FHNC/4 contributions to the energy and tested them in a number of simple model cases, including liquid {sup 3}He and Bethe`s homework problem. We get reasonable, but not exact agreement with earlier published work. In nuclear and neutron matter with the Argonne v{sub 14} interaction these contributions are indeed small corrections at normal density and grow to only 5-10 MeV/nucleon at 5 times normal density.

Wiringa, R.B.

1995-08-01

383

Fluctuations and the QCD phase diagram  

SciTech Connect

In this contribution the role of quantum fluctuations for the QCD phase diagram is discussed. This concerns in particular the importance of the matter back-reaction to the gluonic sector. The impact of these fluctuations on the location of the confinement/deconfinement and the chiral transition lines as well as their interrelation are investigated. Consequences of our findings for the size of a possible quarkyonic phase and location of a critical endpoint in the phase diagram are drawn.

Schaefer, B.-J., E-mail: bernd-jochen.schaefer@uni-graz.at [Karl-Franzens-Universitaet, Institut fuer Physik (Austria)

2012-06-15

384

The plutonium-oxygen phase diagram  

Microsoft Academic Search

Identification of products formed by the reaction of plutonium metal with liquid water at 23°C indicates that the plutonium-oxygen phase diagram is similar to the cerium-oxygen and praseodymium-oxygen diagrams. Quantitative measurements of Hâ formation and analytical data suggest that a sequence of hydrolysis reactions produces oxide hydrides of trivalent plutonium, PuâOâ, mixed-valent oxides and PuOâ. The intermediate oxides are the

Haschke

1990-01-01

385

Steps toward a radio HR diagram  

Microsoft Academic Search

We discuss the possibility of establishing a set of observational parameters for radio galaxies which could be used to study radio source evolution in the same way that the Hertzsprung-Russell diagram is used to understand stellar evolution. As a first step towards a radio H-R diagram, we show that the FRI\\/II break is a function of both radio and optical

Frazer Owen

386

Family of Orbiters  

NASA Technical Reports Server (NTRS)

This image shows the paths of three spacecraft currently in orbit around Mars, as well as the path by which NASA's Phoenix Mars Lander will approach and land on the planet. The t-shaped crosses show where the orbiters will be when Phoenix enters the atmosphere, while the x-shaped crosses show their location at landing time.

All three orbiters, NASA's Mars Reconnaissance Orbiter, NASA's Mars Odyssey and the European Space Agency's Mars Express, will be monitoring Phoenix during the final steps of its journey to the Red Planet.

Phoenix will land just south of Mars's north polar ice cap.

2008-01-01

387

Pseudoatom molecular dynamics  

NASA Astrophysics Data System (ADS)

An approach to simulating warm and hot dense matter that combines density-functional-theory-based calculations of the electronic structure to classical molecular dynamics simulations with pair interaction potentials is presented. The method, which we call pseudoatom molecular dynamics, can be applied to single-component or multicomponent plasmas. It gives equation of state and self-diffusion coefficients with an accuracy comparable to orbital-free molecular dynamics simulations but is computationally much more efficient.

Starrett, C. E.; Daligault, J.; Saumon, D.

2015-01-01

388

Weyl group orbits on Kac–Moody root systems  

NASA Astrophysics Data System (ADS)

Let D be a Dynkin diagram and let \\Pi =\\{{{? }1},...,{{? }\\ell }\\} be the simple roots of the corresponding Kac–Moody root system. Let h denote the Cartan subalgebra, let W denote the Weyl group and let ? denote the set of all roots. The action of W on h, and hence on ?, is the discretization of the action of the Kac–Moody algebra. Understanding the orbit structure of W on ? is crucial for many physical applications. We show that for i\

Carbone, Lisa; Conway, Alexander; Freyn, Walter; Penta, Diego

2014-11-01

389

Titan Orbiter Aerorover Mission  

NASA Technical Reports Server (NTRS)

We propose a combined Titan orbiter and Titan Aerorover mission with an emphasis on both in situ and remote sensing measurements of Titan's surface, atmosphere, ionosphere, and magnetospheric interaction. The biological aspect of the Titan environment will be emphasized by the mission (i.e., search for organic materials which may include simple organics to 'amono' analogues of amino acids and possibly more complex, lightening detection and infrared, ultraviolet, and charged particle interactions with Titan's surface and atmosphere). An international mission is assumed to control costs. NASA will provide the orbiter, launch vehicle, DSN coverage and operations, while international partners will provide the Aerorover and up to 30% of the cost for the scientific instruments through collaborative efforts. To further reduce costs we propose a single PI for orbiter science instruments and a single PI for Aerorover science instruments. This approach will provide single command/data and power interface between spacecraft and orbiter instruments that will have redundant central DPU and power converter for their instruments. A similar approach could be used for the Aerorover. The mission profile will be constructed to minimize conflicts between Aerorover science, orbiter radar science, orbiter radio science, orbiter imaging science, and orbiter fields and particles (FP) science. Additional information is contained in the original extended abstract.

Sittler Jr., E. C.; Acuna, M.; Burchell, M. J.; Coates, A.; Farrell, W.; Flasar, M.; Goldstein, B. E.; Gorevan, S.; Hartle, R. E.; Johnson, W. T. K.

2001-01-01

390

Orbital trapdoor fractures  

PubMed Central

Orbital trapdoor fractures are commonly encountered in children. Awareness of trapdoor fractures is of particular importance. This is because early recognition and treatment are necessary to prevent permanent motility abnormities. In this article, we will provide a brief overview of orbital fractures. The clinical and radiographic features of trapdoor fractures will then be reviewed, followed by a discussion on their proper management. PMID:23961006

Phan, Laura T.; Jordan Piluek, W.; McCulley, Timothy J.

2012-01-01

391

Orbits R Us!  

NSDL National Science Digital Library

This site introduces the principle of geosynchronous orbits and geostationary weather satellites in non-technical terms. Several animations show how they work. The GOES (Geostationary Operational Environmental Satellite) and POES (Polar-orbiting Operational Environmental Satellites) satellite programs at NASA and NOAA are briefly explained.

392

Idiopathic orbital myositis mimicking orbital cellulitis.  

PubMed

Idiopathic orbital myositis (IOM) is a subtype of orbital inflammatory disease characterized by primarily involving the extraocular muscle. The signs and symptoms of IOM may also be seen in such processes as orbital cellulitis, primary or metastatic orbital neoplasm, carotid-cavernous fistulae, arteriovenous malformations, cavernous sinus thrombosis, and thyroid eye disease, and because there is no pathognomonic sign, symptoms, laboratory test, or radiologic findings, its diagnosis is often provisional. In our case, diagnosis of IOM was more difficult because our patient presented with proptosis after alloplastic implant insertion in the blow-out fracture. After considering radiologic and physical findings, we concluded that cellulitis was more likely as initial diagnosis. To remove foreign body or pus, surgical exploration was done, but intraoperative findings did not show any pus or sign of infection but diffuse enlargement and swelling of inferior rectus muscle. The diagnosis was confirmed as IOM, and the patient was treated with systemic corticosteroid. Although proptosis after alloplastic insertion in blow-out fracture is usually a sign of cellulitis, this case illustrates that it may also occur in patients with IOM. PMID:20485087

Kim, Dong Seok; Lee, Jung Ho; Oh, Deuk Young; Seo, Je Won; Ahn, Sang Tae; Rhie, Jong Won

2010-05-01

393

Moon Lunar Orbiter - Lunar Orbiter III  

NASA Technical Reports Server (NTRS)

The hidden or dark side of the Moon was taken by Lunar Orbiter III During its mission to photograph potential lunar-landing sites for Apollo missions. Photograph published in Winds of Change, 75th Anniversary NASA publication (page 94), by James Schultz.

1967-01-01

394

Mars Climate Orbiter  

NASA Technical Reports Server (NTRS)

The purpose of this mission is to study the climate history and the water distribution of Mars. Beautiful panoramic views of the shuttle on the launch pad, engine ignition, Rocket launch, and the separation and burnout of the Solid Rocket Boosters are shown. The footage also includes an animation of the mission. Detailed views of the path that the Orbiter traversed were shown. Once the Orbiter lands on the surface of Mars, it will dig a six to eight inch hole and collect samples from the planets' surface. The animation also included the prospective return of the Orbiter to Earth over the desert of Utah. The remote sensor on the Orbiter helps in finding the exact location of the Orbiter so that scientists may collect the sample and analyze it.

1998-01-01

395

Remote Controlled Orbiter Capability  

NASA Technical Reports Server (NTRS)

The Remote Control Orbiter (RCO) capability allows a Space Shuttle Orbiter to perform an unmanned re-entry and landing. This low-cost capability employs existing and newly added functions to perform key activities typically performed by flight crews and controllers during manned re-entries. During an RCO landing attempt, these functions are triggered by automation resident in the on-board computers or uplinked commands from flight controllers on the ground. In order to properly route certain commands to the appropriate hardware, an In-Flight Maintenance (IFM) cable was developed. Currently, the RCO capability is reserved for the scenario where a safe return of the crew from orbit may not be possible. The flight crew would remain in orbit and await a rescue mission. After the crew is rescued, the RCO capability would be used on the unmanned Orbiter in an attempt to salvage this national asset.

Garske, Michael; delaTorre, Rafael

2007-01-01

396

Orbital Debris Mitigation  

NASA Technical Reports Server (NTRS)

Policies on limiting orbital debris are found throughout the US Government, many foreign space agencies, and as adopted guidelines in the United Nations. The underlying purpose of these policies is to ensure the environment remains safe for the operation of robotic and human spacecraft in near- Earth orbit. For this reason, it is important to consider orbital debris mitigation during the design of all space vehicles. Documenting compliance with the debris mitigation guidelines occurs after the vehicle has already been designed and fabricated for many CubeSats, whereas larger satellites are evaluated throughout the design process. This paper will provide a brief explanation of the US Government Orbital Debris Mitigation Standard Practices, a discussion of international guidelines, as well as NASA's process for compliance evaluation. In addition, it will discuss the educational value of considering orbital debris mitigation requirements as a part of student built satellite design.

Kelley, R. L.; Jarkey, D. R.; Stansbery, G.

2014-01-01

397

The new concept of the orbital theory of paleoclimate  

NASA Astrophysics Data System (ADS)

The comparison of the Phanerosoic climatic changes, characterized by the orbital periodicities, with the theories of Croll (1875) and Milankovitch (1930) lead me to the formulation of the new cocept of the orbital theory of paleoclimate (Bol’shakov, 2001). It consists of two main principles: 1)The extent and type of the climatic effect of variations in orbital elements depend on the global paleoclimatic state of the Earth (ranging from glacial to thermal epochs); this state is most probably determined by both terrestrial and extraterrestrial factors; 2)The determination of the climatic significance of variations in individual orbital elements should take into account the following aspects: (a) specific character of the continuous in time (annual) and space (for the whole Earth) insolation variations, related to the variations in all three orbital elements, and (b) terrestrial climatic feedback mechanisms transforming the orbital signals into the global climatic changes. It is obvious from the new concept formulation, that the paleoclimatic simulation (and the plotting of the paleoclimatic curve) is the extremely difficult task. Because I supposed the simplified method for the plotting of the Pleistocene paleoclimatic curve, which was called orbital-climatic diagram (OCD; Bol’shakov, 2000). This method is based on a simple, general and commonly adopted mechanisms of the global climatic influences of the variations in all orbital elements. Generally good similarity between the orbital-climatic diagram and oxygen isotope curves for the fist time directly confirms the determining influence of the orbital insolation variations on the rhythm and tendency of the global climatic changes over the last million years. It should be noted, that the new concept of the orbital theory of paleoclimate allows to solve on the basis of a unified system of notions the majority of problems, such as the problem of the 100-kyr climatic cyclicity, the absence of the eccentricity’s 400 kyr climatic periodicity in the Pleistocene, the transition, about 1 million years ago, the main climatic periodicity from 41 thousand years to about 100 thousand years and so on. Contrary to the widespread opinion, the seasonal precession insolation variations have had the least effect on the global climatic changes in the Quaternary. The new concept leads to new ideas about the main factors, driving the Phanerosoic climatic changes, characterized by the orbital periodicities.

Bolshakov, V. A.

2003-04-01

398

On phase diagrams of magnetic reconnection  

SciTech Connect

Recently, “phase diagrams” of magnetic reconnection were developed to graphically organize the present knowledge of what type, or phase, of reconnection is dominant in systems with given characteristic plasma parameters. Here, a number of considerations that require caution in using the diagrams are pointed out. First, two known properties of reconnection are omitted from the diagrams: the history dependence of reconnection and the absence of reconnection for small Lundquist number. Second, the phase diagrams mask a number of features. For one, the predicted transition to Hall reconnection should be thought of as an upper bound on the Lundquist number, and it may happen for considerably smaller values. Second, reconnection is never “slow,” it is always “fast” in the sense that the normalized reconnection rate is always at least 0.01. This has important implications for reconnection onset models. Finally, the definition of the relevant Lundquist number is nuanced and may differ greatly from the value based on characteristic scales. These considerations are important for applications of the phase diagrams. This is demonstrated by example for solar flares, where it is argued that it is unlikely that collisional reconnection can occur in the corona.

Cassak, P. A. [Department of Physics, West Virginia University, Morgantown, West Virginia 26506 (United States)] [Department of Physics, West Virginia University, Morgantown, West Virginia 26506 (United States); Drake, J. F. [IREAP, University of Maryland, College Park, Maryland 20742-3511 (United States)] [IREAP, University of Maryland, College Park, Maryland 20742-3511 (United States)

2013-06-15

399

Science Visual Literacy: Learners' Perceptions and Knowledge of Diagrams  

ERIC Educational Resources Information Center

Constructing meaning from science texts relies not only on comprehending the words but also the diagrams and other graphics. The goal of this study was to explore elementary students' perceptions of science diagrams and their skills related to diagram interpretation. 30 students, ranging from second grade through middle school, completed a diagram

McTigue, Erin M.; Flowers, Amanda C.

2011-01-01

400

Evolution of HR Diagrams So as a cluster ages, the  

E-print Network

Evolution of HR Diagrams So as a cluster ages, the main sequence `burns down' in order. lifetime Diagram to Determine the Age of a Star Cluster #12;Evolution of HR Diagrams So as a cluster ages, the main of plotting stars, we represent them with a line of constant age. Using the H-R Diagram to Determine the Age

Barnes, Joshua Edward

401

Extraction, layout analysis and classification of diagrams in PDF documents  

Microsoft Academic Search

Diagrams are a critical part of virtually all scientific and technical documents. Analyzing diagrams will be important for building comprehensive document retrieval systems. This paper focuses on the extraction and classification of diagrams from PDF documents. We study diagrams available in vector (not raster) format in online research papers. PDF files are parsed and their vector graphics components installed in

Robert P. Futrelle; Mingyan Shao; Chris Cieslik; Andrea Elaina Grimes

2003-01-01

402

49 CFR 1152.10 - System diagram map.  

Code of Federal Regulations, 2010 CFR

...2010-10-01 false System diagram map. 1152.10 Section 1152.10 Transportation...Diagram § 1152.10 System diagram map. (a) Each carrier shall prepare a diagram of its rail system on a map, designating all lines in its...

2010-10-01

403

Practical guidelines for the readability of IT-architecture diagrams  

Microsoft Academic Search

This paper presents the work done to establish guidelines for the creation of readable IT-architecture diagrams and gives some examples of guidelines and some examples of improved diagrams. These guidelines are meant to assist practicing IT-architects in preparing the diagrams to communicate their architectures to the various stakeholders. Diagramming has always been important in information technology (IT), but the recent

Henk Koning; Claire Dormann; Hans van Vliet

2002-01-01

404

Measurement of Eye Diagrams and Constellation Diagrams of Optical Sources Using Linear Optics and Waveguide Technology  

Microsoft Academic Search

We demonstrate the characterization of optical sources with high sensitivity, high temporal resolution, and phase sensitivity using linear optical sampling. Eye diagrams and constellation diagrams are reconstructed using the interference of the source under test with a train of sampling pulses. This concept is implemented using a waveguide optical hybrid, which splits and recombines the sources and adjusts the phase

C. Dorrer; Christopher Richard Doerr; I. Kang; Roland Ryf; J. Leuthold; P. J. Winzer

2005-01-01

405

Dynamics of Orbits Near 3:1 Resonance in the Earth-Moon System  

NASA Astrophysics Data System (ADS)

The Interstellar Boundary Explorer (IBEX) spacecraft is currently in a highly elliptical orbit around Earth with a period near 3:1 resonance with the Moon. Its orbit is oriented so that apogee does not approach the Moon. Simulations show this orbit to be remarkably stable over the next 20 years. This article examines the dynamics of such orbits in the Circular Restricted 3-Body Problem (CR3BP). We look at three types of periodic orbits, each exhibiting a type of symmetry of the CR3BP. For each of the orbit types, we assess the local stability using Floquet analysis. Although not all of the periodic solutions are stable in the mathematical sense, any divergence is so slow as to produce practical stability over several decades. We use Poincaré maps with twenty-year propagations to assess the nonlinear stability of the orbits, where the perturbation magnitudes are related to the orbit uncertainty for the IBEX mission. Finally we show that these orbits belong to a family of orbits connected in a bifurcation diagram that exhibits exchange of stability. The analysis of these families of period orbits provides a valuable starting point for a mission orbit trade study.

Dichmann, Donald J.; Lebois, Ryan; Carrico, John P.

2014-08-01

406

Fingerprints of spin-orbital entanglement in transition metal oxides.  

PubMed

The concept of spin-orbital entanglement on superexchange bonds in transition metal oxides is introduced and explained on several examples. It is shown that spin-orbital entanglement in superexchange models destabilizes the long-range (spin and orbital) order and may lead either to a disordered spin-liquid state or to novel phases at low temperature which arise from strongly frustrated interactions. Such novel ground states cannot be described within the conventionally used mean field theory which separates spin and orbital degrees of freedom. Even in cases where the ground states are disentangled, spin-orbital entanglement occurs in excited states and may become crucial for a correct description of physical properties at finite temperature. As an important example of this behaviour we present spin-orbital entanglement in the RV O(3) perovskites, with R = La,Pr,…,Y b,Lu, where the finite temperature properties of these compounds can be understood only using entangled states: (i) the thermal evolution of the optical spectral weights, (ii) the dependence of the transition temperatures for the onset of orbital and magnetic order on the ionic radius in the phase diagram of the RV O(3) perovskites, and (iii) the dimerization observed in the magnon spectra for the C-type antiferromagnetic phase of Y V O(3). Finally, it is shown that joint spin-orbital excitations in an ordered phase with coexisting antiferromagnetic and alternating orbital order introduce topological constraints for the hole propagation and will thus radically modify the transport properties in doped Mott insulators where hole motion implies simultaneous spin and orbital excitations. PMID:22776856

Ole?, Andrzej M

2012-08-01

407

Fingerprints of spin-orbital entanglement in transition metal oxides  

E-print Network

The concept of spin-orbital entanglement on superexchange bonds in transition metal oxides is introduced and explained on several examples. It is shown that spin-orbital entanglement in superexchange models destabilizes the long-range (spin and orbital) order and may lead either to a disordered spin-liquid state or to novel phases at low temperature which arise from strongly frustrated interactions. Such novel ground states cannot be described within the conventionally used mean field theory which separates spin and orbital degrees of freedom. Even in cases where the ground states are disentangled, spin-orbital entanglement occurs in excited states and may become crucial for a correct description of physical properties at finite temperature. As an important example of this behaviour we present spin-orbital entanglement in the $R$VO$_3$ perovskites, with $R$=La,Pr,...,Yb,Lu, where such finite temperature properties of these compounds can be understood only using entangled states: ($i$) thermal evolution of the optical spectral weights, ($ii$) the dependence of transition temperatures for the onset of orbital and magnetic order on the ionic radius in the phase diagram of the $R$VO$_3$ perovskites, and ($iii$) dimerization observed in the magnon spectra for the $C$-type antiferromagnetic phase of YVO$_3$. Finally, it is shown that joint spin-orbital excitations in an ordered phase with coexisting antiferromagnetic and alternating orbital order introduces topological constraints for the hole propagation and will thus radically modify transport properties in doped Mott insulators where hole motion implies simultaneous spin and orbital excitations.

Andrzej M. Ole?

2012-07-12

408

Visualization of atom's orbits.  

PubMed

High-resolution imaging techniques have been used to obtain views of internal shapes of single atoms or columns of atoms. This review article focuses on the visualization of internal atomic structures such as the configurations of electron orbits confined to atoms. This is accomplished by applying visualization techniques to the reported images of atoms or molecules as well as static and dynamic ions in a plasma. It was found that the photon and electron energies provide macroscopic and microscopic views of the orbit structures of atoms, respectively. The laser-imaged atoms showed a rugged orbit structure, containing alternating dark and bright orbits believed to be the pathways for an externally supplied laser energy and internally excited electron energy, respectively. By contrast, the atoms taken by the electron microscopy provided a structure of fine electron orbits, systematically formed in increasing order of grayscale representing the energy state of an orbit. This structure was identical to those of the plasma ions. The visualized electronic structures played a critical role in clarifying vague postulates made in the Bohr model. Main features proposed in the atomic model are the dynamic orbits absorbing an externally supplied electromagnetic energy, electron emission from them while accompanying light radiation, and frequency of electron waves not light. The light-accompanying electrons and ionic speckles induced by laser light signify that light is composed of electrons and ions. PMID:24749452

Kim, Byungwhan

2014-02-01

409

External Resource: What is orbit?  

NSDL National Science Digital Library

A 5-8 NASA Education reference answering the question, " What is orbit?" Topics include: satellite, ecliptic plane, perigee, apogee, escape velocity, geosynchronous, polar orbits, and low Earth orbit.

1900-01-01

410

Removal of orbital debris  

NASA Technical Reports Server (NTRS)

The several methods presently identified for the reduction of orbital debris populations are broadly classifiable as either preventive or remedial, and fall within distinctive operational regimes. For all particles, (1) in the 250-2000-km altitude band, intelligent sweepers may be used; (2) for large objects, in the 80-250-km altitude band, orbital decay renders removal impractical; (3) for the 250-750-km altitude band, deorbit devices should be used; (4) for 750-2500-km altitude, OMV rendezvous for propulsive deorbit package attachment is foreseeable; and beyond 2500 km, (5) propulsive escape from earth orbit is required.

Petro, Andrew J.; Talent, David L.

1989-01-01

411

Space Shuttle Orbiter  

NSDL National Science Digital Library

Students learn how orbits are created by a force pulling toward the center in this Moveable Museum unit, in which they build a paper model of a Space Shuttle. This activity simulates an object in orbit. A paper Space Shuttle is swung in a circle on a string. The string provides a pull toward the center of the orbit, simulating the force of gravity. The four-page PDF guide includes suggested background readings for educators, activity notes, and step-by-step directions with suggested discussion questions for older students.

412

Monitoring Secular Orbital Period Variations of Some Eclipsing Binaries at the Ankara University Observatory  

NASA Astrophysics Data System (ADS)

This study concerns the long-term monitoring of the secular variation character in the orbital period of some short-period eclipsing binaries observed at the Ankara University Observatory. Among the systems of our observing list are CK Boo, V502 Oph and V836 Cyg that show long-term secular variations in their orbital periods. We use classical O-C diagram analysis technique as a tool to reveal the character of the period variations of these binary systems.

Yüce, K.; Selam, S. O.; Albayrak, B.; Ak, T.

2006-08-01

413

Three-body spin-orbit forces from chiral two-pion exchange  

Microsoft Academic Search

Using chiral perturbation theory, we calculate the density-dependent spin-orbit coupling generated by the two-pion exchange three-nucleon interaction involving virtual Delta -isobar excitation. From the corresponding three-loop Hartree and Fock diagrams we obtain an isoscalar spin-orbit strength Fso ( kf ) which amounts at nuclear matter saturation density to about half of the empirical value of 90 MeV fm5 . The

N. Kaiser

2003-01-01

414

Phase separation in a polarized Fermi gas with spin-orbit coupling  

SciTech Connect

We study the phase separation of a spin-polarized Fermi gas with spin-orbit coupling near a wide Feshbach resonance. As a result of the competition between spin-orbit coupling and population imbalance, the phase diagram for a uniform gas develops a rich structure of phase separation involving topologically nontrivial gapless superfluid states. We then demonstrate the phase separation induced by an external trapping potential and discuss the optimal parameter region for the experimental observation of the gapless superfluid phases.

Yi, W.; Guo, G.-C. [Key Laboratory of Quantum Information, University of Science and Technology of China, CAS, Hefei, Anhui, 230026 (China)

2011-09-15

415

A pseudo-haptic knot diagram interface  

NASA Astrophysics Data System (ADS)

To make progress in understanding knot theory, we will need to interact with the projected representations of mathematical knots which are of course continuous in 3D but significantly interrupted in the projective images. One way to achieve such a goal would be to design an interactive system that allows us to sketch 2D knot diagrams by taking advantage of a collision-sensing controller and explore their underlying smooth structures through a continuous motion. Recent advances of interaction techniques have been made that allow progress to be made in this direction. Pseudo-haptics that simulates haptic effects using pure visual feedback can be used to develop such an interactive system. This paper outlines one such pseudo-haptic knot diagram interface. Our interface derives from the familiar pencil-and-paper process of drawing 2D knot diagrams and provides haptic-like sensations to facilitate the creation and exploration of knot diagrams. A centerpiece of the interaction model simulates a "physically" reactive mouse cursor, which is exploited to resolve the apparent conflict between the continuous structure of the actual smooth knot and the visual discontinuities in the knot diagram representation. Another value in exploiting pseudo-haptics is that an acceleration (or deceleration) of the mouse cursor (or surface locator) can be used to indicate the slope of the curve (or surface) of whom the projective image is being explored. By exploiting these additional visual cues, we proceed to a full-featured extension to a pseudo-haptic 4D visualization system that simulates the continuous navigation on 4D objects and allows us to sense the bumps and holes in the fourth dimension. Preliminary tests of the software show that main features of the interface overcome some expected perceptual limitations in our interaction with 2D knot diagrams of 3D knots and 3D projective images of 4D mathematical objects.

Zhang, Hui; Weng, Jianguang; Hanson, Andrew J.

2011-01-01

416

Orbit Determination Issues for Libration Point Orbits  

NASA Technical Reports Server (NTRS)

Libration point mission designers require knowledge of orbital accuracy for a variety of analyses including station keeping control strategies, transfer trajectory design, and formation and constellation control. Past publications have detailed orbit determination (OD) results from individual libration point missions. This paper collects both published and unpublished results from four previous libration point missions (ISEE (International Sun-Earth Explorer) -3, SOHO (Solar and Heliospheric Observatory), ACE (Advanced Composition Explorer) and MAP (Microwave Anisotropy Probe)) supported by Goddard Space Flight Center's Guidance, Navigation & Control Center. The results of those missions are presented along with OD issues specific to each mission. All past missions have been limited to ground based tracking through NASA ground sites using standard range and Doppler measurement types. Advanced technology is enabling other OD options including onboard navigation using seaboard attitude sensors and the use of the Very Long Baseline Interferometry (VLBI) measurement Delta Differenced One-Way Range (DDOR). Both options potentially enable missions to reduce coherent dedicated tracking passes while maintaining orbital accuracy. With the increased projected loading of the DSN (Deep Space Network), missions must find alternatives to the standard OD scenario.

Beckman, Mark; Bauer, Frank (Technical Monitor)

2002-01-01

417

Orbit Determination Issues for Libration Point Orbits  

NASA Technical Reports Server (NTRS)

Libration point mission designers require knowledge of orbital accuracy for a variety of analyses including station keeping control strategies, transfer trajectory design, and formation and constellation control. Past publications have detailed orbit determination (OD) results from individual notation point missions. This paper collects both published and unpublished results from four previous notation point missions (ISEE-3, SOHO, ACE and MAP) supported by Goddard Space Flight Center's Guidance, Navigation & Control Center. The results of those missions are presented along with OD issues specific to each mission. All past missions have been limited to ground based tracking through NASA ground sites using standard marine and Doppler measurement types. Advanced technology is enabling other OD options including onboard navigation using onboard attitude sensors and the use of the Very Long Baseline Interferometry (VLBI) measurement Delta Differenced One-Way Range (DDOR). Both options potentially enable missions to reduce coherent dedicated tracking passes while maintaining orbital accuracy. With the increased projected loading of the DSN, missions must find alternatives to the standard OD scenario.

Beckman, Mark; Bauer, Frank (Technical Monitor)

2002-01-01

418

Altimetry, Orbits and Tides  

NASA Technical Reports Server (NTRS)

The nature of the orbit error and its effect on the sea surface heights calculated with satellite altimetry are explained. The elementary concepts of celestial mechanics required to follow a general discussion of the problem are included. Consideration of errors in the orbits of satellites with precisely repeating ground tracks (SEASAT, TOPEX, ERS-1, POSEIDON, amongst past and future altimeter satellites) are detailed. The theoretical conclusions are illustrated with the numerical results of computer simulations. The nature of the errors in this type of orbits is such that this error can be filtered out by using height differences along repeating (overlapping) passes. This makes them particularly valuable for the study and monitoring of changes in the sea surface, such as tides. Elements of tidal theory, showing how these principles can be combined with those pertinent to the orbit error to make direct maps of the tides using altimetry are presented.

Colombo, O. L.

1984-01-01

419

Habitability study shuttle orbiter  

NASA Technical Reports Server (NTRS)

Habitability design concepts for the Shuttle Orbiter Program are provided for MSC. A variety of creative solutions for the stated tasks are presented. Sketches, mock-ups, mechanicals and models are included for establishing a foundation for future development.

1973-01-01

420

Imaging in orbital trauma  

PubMed Central

Orbital trauma is one of the most common reasons for ophthalmology specialty consultation in the emergency department setting. We survey the literature from 1990 to present to describe the role of computed tomography (CT), magnetic resonance imaging (MRI) and their associated angiography in some of the most commonly encountered orbital trauma conditions. CT orbit can often detect certain types of foreign bodies, lens dislocation, ruptured globe, choroidal or retinal detachments, or cavernous sinus thrombosis and thus complement a bedside ophthalmic exam that can sometimes be limited in the setting of trauma. CT remains the workhorse for acute orbital trauma owing to its rapidity and ability to delineate bony abnormalities; however MRI remains an important modality in special circumstances such as soft tissue assessment or with organic foreign bodies. PMID:23961028

Lin, Ken Y.; Ngai, Philip; Echegoyen, Julio C.; Tao, Jeremiah P.

2012-01-01

421

Orbiter thermal protection system  

NASA Technical Reports Server (NTRS)

The major material and design challenges associated with the orbiter thermal protection system (TPS), the various TPS materials that are used, the different design approaches associated with each of the materials, and the performance during the flight test program are described. The first five flights of the Orbiter Columbia and the initial flight of the Orbiter Challenger provided the data necessary to verify the TPS thermal performance, structural integrity, and reusability. The flight performance characteristics of each TPS material are discussed, based on postflight inspections and postflight interpretation of the flight instrumentation data. Flights to date indicate that the thermal and structural design requirements for the orbiter TPS are met and that the overall performance is outstanding.

Dotts, R. L.; Curry, D. M.; Tillian, D. J.

1985-01-01

422

Orbit Physlet Problems  

NSDL National Science Digital Library

A Danish Website for Interactive Science Education. Html pages in this directory contain scripts that were written by Morten Brydensholt and coworkers for the Orbit website. This commercial website is in Danish. This site provides English translations of this material.

Wolfgang Christian

423

Optical orbital debris spotter  

NASA Astrophysics Data System (ADS)

The number of man-made debris objects orbiting the Earth, or orbital debris, is alarmingly increasing, resulting in the increased probability of degradation, damage, or destruction of operating spacecraft. In part, small objects (<10 cm) in Low Earth Orbit (LEO) are of concern because they are abundant and difficult to track or even to detect on a routine basis. Due to the increasing debris population it is reasonable to assume that improved capabilities for on-orbit damage attribution, in addition to increased capabilities to detect and track small objects are needed. Here we present a sensor concept to detect small debris with sizes between approximately 1.0 and 0.01 cm in the vicinity of a host spacecraft for near real time damage attribution and characterization of dense debris fields and potentially to provide additional data to existing debris models.

Englert, Christoph R.; Bays, J. Timothy; Marr, Kenneth D.; Brown, Charles M.; Nicholas, Andrew C.; Finne, Theodore T.

2014-11-01

424

Imaging in orbital trauma.  

PubMed

Orbital trauma is one of the most common reasons for ophthalmology specialty consultation in the emergency department setting. We survey the literature from 1990 to present to describe the role of computed tomography (CT), magnetic resonance imaging (MRI) and their associated angiography in some of the most commonly encountered orbital trauma conditions. CT orbit can often detect certain types of foreign bodies, lens dislocation, ruptured globe, choroidal or retinal detachments, or cavernous sinus thrombosis and thus complement a bedside ophthalmic exam that can sometimes be limited in the setting of trauma. CT remains the workhorse for acute orbital trauma owing to its rapidity and ability to delineate bony abnormalities; however MRI remains an important modality in special circumstances such as soft tissue assessment or with organic foreign bodies. PMID:23961028

Lin, Ken Y; Ngai, Philip; Echegoyen, Julio C; Tao, Jeremiah P

2012-10-01

425

Tethered orbital refueling study  

NASA Technical Reports Server (NTRS)

One of the major applications of the space station will be to act as a refueling depot for cryogenic-fueled space-based orbital transfer vehicles (OTV), Earth-storable fueled orbit maneuvering vehicles, and refurbishable satellite spacecraft using hydrazine. One alternative for fuel storage at the space station is a tethered orbital refueling facility (TORF), separated from the space station by a sufficient distance to induce a gravity gradient force that settles the stored fuels. The technical feasibility was examined with the primary focus on the refueling of LO2/LH2 orbital transfer vehicles. Also examined was the tethered facility on the space station. It was compared to a zero-gravity facility. A tethered refueling facility should be considered as a viable alternative to a zero-gravity facility if the zero-gravity fluid transfer technology, such as the propellant management device and no vent fill, proves to be difficult to develop with the required performance.

Fester, Dale A.; Rudolph, L. Kevin; Kiefel, Erlinda R.; Abbott, Peter W.; Grossrode, Pat

1986-01-01

426

Aerobraking orbital transfer vehicle  

NASA Technical Reports Server (NTRS)

An aerobraking orbital transfer vehicle which includes an aerobraking device which also serves as a heat shield in the shape of a raked-off elliptic or circular cone with a circular or elliptical base, and with an ellipsoid or other blunt shape nose. The aerobraking device is fitted with a toroid-like skirt and is integral with the support structure of the propulsion system and other systems of the space vehicle. The vehicle is intended to be transported in components to a space station in lower earth orbit where it is assembled for use as a transportation system from low earth orbit to geosynchronous earth orbit and return. Conventional guidance means are included for autonomous flight.

Scott, Carl D. (Inventor); Nagy, Kornel (Inventor); Roberts, Barney B. (Inventor); Ried, Robert C. (Inventor); Kroll, Kenneth R. (Inventor); Gamble, Joe (Inventor)

1989-01-01

427

Space: Orbiting the Earth  

NSDL National Science Digital Library

In this activity, students solve various problems related to John Glenn's first ride into space, and complete calculations involving velocity, distance and time. Then they calculate the height a satellite would need to be to keep to a geosynchronous orbit.

2010-01-01

428

Orbiter entry aerothermodynamics  

NASA Technical Reports Server (NTRS)

The challenge in the definition of the entry aerothermodynamic environment arising from the challenge of a reliable and reusable Orbiter is reviewed in light of the existing technology. Select problems pertinent to the orbiter development are discussed with reference to comprehensive treatments. These problems include boundary layer transition, leeward-side heating, shock/shock interaction scaling, tile gap heating, and nonequilibrium effects such as surface catalysis. Sample measurements obtained from test flights of the Orbiter are presented with comparison to preflight expectations. Numerical and wind tunnel simulations gave efficient information for defining the entry environment and an adequate level of preflight confidence. The high quality flight data provide an opportunity to refine the operational capability of the orbiter and serve as a benchmark both for the development of aerothermodynamic technology and for use in meeting future entry heating challenges.

Ried, R. C.

1985-01-01

429

Ulysses orbit determination  

NASA Astrophysics Data System (ADS)

The Ulysses mission ESA spacecraft with ESA and NASA experiments explores the polar regions of the sun by sending a spacecraft on a trajectory out of the ecliptic after a Jupiter flyby. After correcting for launch errors and refining the aimpoint, orbit determination results show the change and general improvement in the Jupiter arrival point. Orbit determination results are further discussed, and future plans are mentioned.

Gordon, H. J.; Luthey, J. L.; McElrath, T. P.; Menon, P. R.

1992-08-01

430

A tapestry of orbits  

SciTech Connect

In this book, the author describes how orbital research developed to yield a rich harvest of knowledge about the earth and its atmosphere. King-Hele relates a personal account of this research based on analysis of satellite orbits between 1957 and 1990 conducted from the Royal Aircraft Establishment in Farnborough England. The early research methods used before the launch of Sputnik in 1957 are discussed.

King-Hele, D.

1992-01-01

431

Orbits of 6 Binaries  

NASA Astrophysics Data System (ADS)

In this paper the orbits of binaries WDS 10093+2020 = A 2145, WDS 21074-0814 = BU 368 AB and WDS 22288-0001 = STF 2909 AB are recalculated because of significant deviations of more recent observations from the ephemerides. For binaries WDS 22384-0754 = A 2695, WDS 23474-7118 = FIN 375 Aa and WDS 23578+2508 = McA 76 the orbital elements are calculated for the first time.

Olevic, D.; Cvetkovic, Z.

432

Pediatric Orbital Fractures  

PubMed Central

It is wise to recall the dictum “children are not small adults” when managing pediatric orbital fractures. In a child, the craniofacial skeleton undergoes significant changes in size, shape, and proportion as it grows into maturity. Accordingly, the craniomaxillofacial surgeon must select an appropriate treatment strategy that considers both the nature of the injury and the child's stage of growth. The following review will discuss the management of pediatric orbital fractures, with an emphasis on clinically oriented anatomy and development. PMID:24436730

Oppenheimer, Adam J.; Monson, Laura A.; Buchman, Steven R.

2013-01-01

433

Phase Diagram and Re-entrant Superconductivity in H-doped LaFeAsO  

NASA Astrophysics Data System (ADS)

Recently, the phase diagram of LaFeAsO1-xHx is reported and two-dome structure of superconducting state, first dome for x<0.2 with Tc^max=29K and second dome for 0.2< x<0.5 with Tc^max=36K, has attract great attention[1]. To clarify the origin of the second superconducting dome, we construct tight-binding models for each doping level x and investigate the spin and orbital fluctuations based on the random phase approximation. We fined that the nesting between electron-hole Fermi surfaces is monotonically weakened with x and spin density wave order with momentum q=(,) disappears. In the over-doped regime for x>0.2, however, the nesting between electron-electron Fermi surfaces increases, and an incommensurate spin density wave order emerges. The orbital order also shows a re-entrant phase diagram. The spin and orbital fluctuations due to the incommensurate nesting would then be the origin of the second superconducting dome reported in the H-over-doped LaFeAsO. The obtained electronic states for x=0.5 are very similar to that for KFe2Se2[2], which is a heavily electron doped system(0.5 electron/Fe). [1] S. Iimura, et al., Nat. Commumn. 3, 943 (2012). [2] T. Saito, et al., Phys. Rev. B 83, 140512 (2011).

Yamakawa, Youichi; Onari, Seiichiro; Kontani, Hiroshi

2013-03-01

434

Overall view of the Orbiter Servicing Structure within the Orbiter ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Overall view of the Orbiter Servicing Structure within the Orbiter Processing Facility at Kennedy Space Center. Can you see any hint of the Orbiter Discovery? It is in there. - Space Transportation System, Orbiter Discovery (OV-103), Lyndon B. Johnson Space Center, 2101 NASA Parkway, Houston, Harris County, TX

435

ECE 423: DSP for Communication Block Diagrams  

E-print Network

and Quantization DSP System Design/Characterization Real-time DSP Hardware and Software - Understands basic signalECE 423: DSP for Communication Block Diagrams Discrete-time System Analysis/Design Sampling experience using MATLAB and Simulink for modeling of linear systems - For both continuous and discrete time

Schumacher, Russ

436

Computer-Generated Diagrams for the Classroom.  

ERIC Educational Resources Information Center

Describes 10 computer programs used to draw diagrams usually drawn on chalkboards, such as addition of three vectors, vector components, range of a projectile, lissajous figures, beats, isotherms, Snell's law, waves passing through a lens, magnetic field due to Helmholtz coils, and three curves. Several programming tips are included. (JN)

Carle, Mark A.; Greenslade, Thomas B., Jr.

1986-01-01

437

Weight diagram construction of Lax operators  

SciTech Connect

We review and expand methods introduced in our previous paper. It is proved that cyclic weight diagrams corresponding to representations of affine Lie algebras allow one to construct the associated Lax operator. The resultant Lax operator is in the Miura-like form and generates the modified KdV equations. The algorithm is extended to the super-symmetric case.

Carbon, S.L.; Piard, E.J.

1991-10-01

438

Dynamic Tactile Diagram Simplification on Refreshable Displays  

ERIC Educational Resources Information Center

The increasing use of visual diagrams in educational and work environments, and even our daily lives, has created obstacles for individuals who are blind or visually impaired to "independently" access the information they represent. Although physical tactile pictures can be created to convey the visual information, it is typically a slow,…

Rastogi, Ravi; Pawluk, Dianne T. V.

2013-01-01

439

Using Euler Diagrams in Traditional Library Environments  

E-print Network

Using Euler Diagrams in Traditional Library Environments J´er^ome Thi`evre, Marie-Luce Viaud 1 INA for traditional library environments, which allows the user to elaborate easily and efficiently new strategies one is an interactive representation of the structures composing the documentary kernel of the library

Verroust-Blondet, Anne

440

The granulation boundary in the HR diagram  

Microsoft Academic Search

A granulation boundary in the H-R diagram is found. The boundary runs smoothly from spectral type G1 Ib to near F0 on the main sequence. On the cool side of the boundary, the spectral line bisectors are of the classical type associated with granulation. On the hot side the bisectors show a reversed slope and curvature indicative of some other

David F. Gray; Thomas Nagel

1989-01-01

441

New developments in understanding the HR diagram  

Microsoft Academic Search

Results of recent research efforts aimed at the interpretation and reproduction of the Hertzsprung-Russell diagram are reviewed. In particular, attention is given to basic stellar evolution; nuclear reactions, opacities, and stellar winds; semiconduction and convective overshoot; and old star clusters. The discussion also covers intermediate age clusters and Cepheid stars and supergiant stars in the Milky Way and LMC.

Cesare Chiosi; Gianpaolo Bertelli; Alessandro Bressan

1992-01-01

442

Synthetic HR-diagrams for massive stars  

Microsoft Academic Search

Observations of luminous stars are compared to synthetic HR diagrams generated from three sets of evolutionary models with different treatment of mass loss, convective overshoot, and considering or not variations in the opacity due to heavy elements. We take into account also different values for the slope of the initial mass function, and the possibility that a fraction of the

E. Nasi; C. Forieri

1990-01-01

443

NTNU Java: Free-Body Force Diagram  

NSDL National Science Digital Library

This applet illustrates the forces on a block on an inclined plane. A free-body diagram shows the gravitational, normal, frictional and net force vectors. The weight, angle of the plane, and coefficient of friction can be changed by the user. The user can also apply an external force to the block. The motion resulting from the forces is not shown.

Hwang, Fu-Kwun

2005-02-07

444

The Keynesian Diagram: A Cross to Bear?  

ERIC Educational Resources Information Center

In elementary economics courses students are often introduced to the basic concepts of macroeconomics through very simplified static models, and the concept of a macroeconomic equilibrium is generally explained with the help of an aggregate demand/aggregate supply (AD/AS) model and an income/expenditure model (via the Keynesian cross diagram).…

Fleck, Juergen

445

Knowledge Visualization Using Optimized General Logic Diagrams  

E-print Network

readable rule vi- sualization in the diagram. This problem has been solved by applying a simulated, such as Microsoft SQL Server 2000 Analysis Services, IBM DB2 Intelligent Miner, and Oracle Data Miner. They are also or more readable and visually attractive. Therefore, a problem arises as to how to optimize the attribute

Michalski, Ryszard S.

446

Phase diagram of the Kondo lattice  

Microsoft Academic Search

We discuss the phase diagram of the Kondo lattice: we generalize to the lattice a method proposed by Yoshimori and Sakurai for the single-impurity Kondo problem; this method transforms the Kondo exchange interaction into a fictitious s-f hybridization, and gives a resonance of width TK at the Fermi level. We study the Kondo phase and compare its energy with the

C. Lacroix; M. Cyrot

1979-01-01

447

Array diagrams and the Nial approach  

Microsoft Academic Search

The Nested Interactive Array Language, Nial, combines APL and LISP concepts and is based on the theory of nested rectangular arrays. Array theory provides a concise mathematical model of data capturing the essence of everyday data objects. Arrays are displayed by diagrams, which provide an easily comprehended way of communicating the rectangularity, nesting and content of arrays. A novel drawing

Fl. Schmidt; M. A. Jenkins

1982-01-01

448

Penguin diagrams for the HYP staggered fermions  

E-print Network

We present results of the one-loop corrections originating from the penguin diagrams for the improved staggered fermion operators constructed using various fat links such as Fat7, Fat7+Lepage, $\\bar{\\rm Fat7}$, HYP (I) and HYP (II). The main results include the diagonal/off-diagonal mixing coefficients and the matching formula between the continuum and lattice operators.

Keunsu Choi; Weonjong Lee

2003-09-15

449

Orbital complexity in a time-dependent potential  

NASA Astrophysics Data System (ADS)

We introduce a method to detect irregular or chaotic orbits in gravitational potentials based on a wavelet transform of stellar orbits. The method is based on a treatment of normalised frequency power-spectrum coefficients, which we interpret as occupation probabilities (or, weights) of individual frequency modes. Each probability is fed to a Shannon information-entropy formula, before summing over the whole spectrum to compute the total entropy \\cal S. This entropy is then monitored in time as the wavelet coefficients change: each orbit is classified as regular or not according to \\cal S and its dispersion. We find that diagrams of entropy versus entropy dispersion allow to identify orbits in a simple and efficient way, similarly to surface-of-section analysis but requiring less integration time. We apply the method to the case of a gravitational potential modulated by the periodic motion of a massive black hole and find that some 19% of stars are now shifted to highly irregular motion as a result of black hole orbital motion. This is the same fraction of stars that orbit within the black hole radius of influence. This is thanks ..

Boily, C. M.; Detemple, L.; Faber, N. T.

2008-12-01

450

A combined reaction class approach with integrated molecular orbital molecular orbital ,,IMOMO... methodology: A practical  

E-print Network

... methodology: A practical tool for kinetic modeling Thanh N. Truong,a) Dilip K. Maity, and Thanh-Thai T. Truong practical computational methodology for predicting thermal rate constants of reactions involving large molecules or a large number of elementary reactions in the same class. This methodology combines

Truong, Thanh N.

451

Mars Geoscience Orbiter and Lunar Geoscience Orbiter  

NASA Technical Reports Server (NTRS)

The feasibility of using the AE/DE Earth orbiting spacecraft design for the LGO and/or MGO missions was determined. Configurations were developed and subsystems analysis was carried out to optimize the suitability of the spacecraft to the missions. The primary conclusion is that the basic AE/DE spacecraft can readily be applied to the LGO mission with relatively minor, low risk modifications. The MGO mission poses a somewhat more complex problem, primarily due to the overall maneuvering hydrazine budget and power requirements of the sensors and their desired duty cycle. These considerations dictate a modification (scaling up) of the structure to support mission requirements.

Fuldner, W. V.; Kaskiewicz, P. F.

1983-01-01

452

Orbital ordering phenomena in d- and f-electron systems  

NASA Astrophysics Data System (ADS)

In recent decades, novel magnetism of d- and f-electron compounds has been discussed very intensively both in experimental and theoretical research fields of condensed matter physics. It has been recognized that these material groups are in the same category of strongly correlated electron systems, while the low-energy physics of d- and f-electron compounds has been separately investigated in rather different manners. One of the common features of both d- and f-electron systems is certainly the existence of active orbital degree of freedom, but in f-electron materials, due to the strong spin-orbit interaction in rare-earth and actinide ions, the physics seems to be quite different from that of d-electron systems. In general, when the number of internal degrees of freedom and relevant interactions is increased, it is possible to obtain a rich phase diagram including large varieties of magnetic phases by using several kinds of theoretical techniques. However, we should not be simply satisfied with the reproduction of a rich phase diagram. It is believed that the more essential point is to seek a simple principle penetrating complicated phenomena in common with d- and f-electron materials, which opens the door to a new stage in orbital physics. In this sense, it is considered to be an important task of this paper to explain common features of magnetism in d- and f-electron systems from a microscopic viewpoint, using a key concept of orbital ordering, in addition to the review of the complex phase diagram of each material group. As a typical d-electron complex material exhibiting orbital order, we first focus on perovskite manganites, in which remarkable colossal magneto-resistance effect has been intensively studied. The manganites provide us with a good platform to understand that a simple mechanism works for the formation of complex spin, charge and orbital ordering. We also explain intriguing striped charge ordering on the orbital-ordered background in nickelates and the effect of orbital ordering to resolve spin frustration in geometrically frustrated eg electron systems. Note that orbital ordering phenomena are also found in t2g electron systems. Here we review recent advances in the understanding of orbital ordering phenomenon in Ca2RuO4. Next we discuss another spin-charge-orbital complex system such as the f-electron compound. After detailed explanation of the construction of microscopic models on the basis of a j-j coupling scheme, we introduce a d-electron-like scenario to understand novel magnetism in some actinide compounds with the HoCoGa5-type tetragonal crystal structure. Finally, we show that complicated multipole order can be understood from the spin-orbital model on the basis of the j-j coupling scheme. As a typical material with multipole order, we pick up NpO2 which has been believed to exhibit peculiar octupole order. Throughout this review, it is emphasized that the same orbital physics works both in d- and f-electron complex materials in spite of the difference between d and f orbitals.

Hotta, Takashi

2006-07-01

453

The orbits in cancer imaging  

PubMed Central

Primary malignant lesions in the orbit are relatively uncommon. However, the orbits are frequently involved in haematogeneous metastasis or by direct extension from malignancies originating from the adjacent nasal cavity or paranasal sinuses. This paper focuses on the more commonly encountered primary orbital malignancies and the mapping of tumour spread into the orbits. PMID:17114076

Chong, V F H

2006-01-01

454

Equation of state and phase diagram of ammonia at high pressures from ab initio simulations.  

PubMed

We present an equation of state as well as a phase diagram of ammonia at high pressures and high temperatures derived from ab initio molecular dynamics simulations. The predicted phases of ammonia are characterized by analyzing diffusion coefficients and structural properties. Both the phase diagram and the subsequently computed Hugoniot curves are compared to experimental results. Furthermore, we discuss two methods that allow us to take into account nuclear quantum effects, which are of considerable importance in molecular fluids. Our data cover pressures up to 330 GPa and a temperature range from 500 K to 10,000 K. This regime is of great interest for interior models of the giant planets Uranus and Neptune, which contain, besides water and methane, significant amounts of ammonia. PMID:23802968

Bethkenhagen, Mandy; French, Martin; Redmer, Ronald

2013-06-21

455

Mars Telecommunications Orbiter, Artist's Concept  

NASA Technical Reports Server (NTRS)

This illustration depicts a concept for NASA's Mars Telecommunications Orbiter in flight around Mars. The orbiter is in development to be the first spacecraft with a primary function of providing communication links while orbiting a foreign planet. The project's plans call for launch in September 2009, arrival at Mars in August 2010 and a mission of six to 10 years while in orbit. Mars Telecommunication Orbiter would serve as the Mars hub for an interplanetery Internet, greatly increasing the information payoff from other future Mars missions. The mission is designed to orbit Mars more than 10 times farther from the planet than orbiters dedicated primarily to science. The high-orbit design minimizes the time that Mars itself blocks the orbiter from communicating with Earth and maximizes the time that the orbiter is above the horizon -- thus capable of communications relay -- for rovers and stationary landers on Mars' surface.

2005-01-01

456

Vibrational spectra (FT-IR and FT-Raman), molecular structure, natural bond orbital, and TD-DFT analysis of L-Asparagine Monohydrate by Density Functional Theory approach  

NASA Astrophysics Data System (ADS)

In this work we report the vibrational spectral analysis of L-Asparagine Monohydrate (LAM) molecule by using FT-IR and FT-Raman spectroscopic techniques. The equilibrium geometry, harmonic vibrational wavenumbers, various bonding features have been computed using density functional B3LYP method with 6-311G(d,p) as basis set. Stability of the molecule arising from hyperconjugative interactions, charge delocalization have been analyzed using natural bond orbital (NBO) analysis. The results show that charge in electron density (ED) in ?* and ?* antibonding orbitals and second order delocalization energies E(2) confirms the occurrence of Intramolecular Charge Transfer (ICT) within the molecule. The energy and oscillator strength calculated by Time-Dependent Density Functional Theory (TD-DFT) complements with the experimental findings. The simulated spectra satisfactorily coincide with the experimental spectra.

Sylvestre, S.; Sebastian, S.; Edwin, S.; Amalanathan, M.; Ayyapan, S.; Jayavarthanan, T.; Oudayakumar, K.; Solomon, S.

2014-12-01

457

Sedna Orbit Comparisons  

NASA Technical Reports Server (NTRS)

These four panels show the location of the newly discovered planet-like object, dubbed 'Sedna,' which lies in the farthest reaches of our solar system. Each panel, moving counterclockwise from the upper left, successively zooms out to place Sedna in context. The first panel shows the orbits of the inner planets, including Earth, and the asteroid belt that lies between Mars and Jupiter. In the second panel, Sedna is shown well outside the orbits of the outer planets and the more distant Kuiper Belt objects. Sedna's full orbit is illustrated in the third panel along with the object's current location. Sedna is nearing its closest approach to the Sun; its 10,000 year orbit typically takes it to far greater distances. The final panel zooms out much farther, showing that even this large elliptical orbit falls inside what was previously thought to be the inner edge of the Oort cloud. The Oort cloud is a spherical distribution of cold, icy bodies lying at the limits of the Sun's gravitational pull. Sedna's presence suggests that this Oort cloud is much closer than scientists believed.

2004-01-01

458

Orbital Fluid Resupply Assessment  

NASA Technical Reports Server (NTRS)

Orbital fluid resupply can significantly increase the cost-effectiveness and operational flexibility of spacecraft, satellites, and orbiting platforms and observatories. Reusable tankers are currently being designed for transporting fluids to space. A number of options exist for transporting the fluids and propellant to the space-based user systems. The fluids can be transported to space either in the Shuttle cargo bay or using expendable launch vehicles (ELVs). Resupply can thus be accomplished either from the Shuttle bay, or the tanker can be removed from the Shuttle bay or launched on an ELV and attached to a carrier such as the Orbital Maneuvering Vehicle (OMV) or Orbital Transfer Vehicle (OTV) for transport to the user to be serviced. A third option involves locating the tanker at the space station or an unmanned platform as a quasi-permanent servicing facility or depot which returns to the ground for recycling once its tanks are depleted. Current modular tanker designs for monopropellants, bipropellants, and water for space station propulsion are discussed. Superfluid helium tankers are addressed, including trade-offs in tanker sizes, shapes to fit the range of ELVs currently available, and boil-off losses associated with longer-term (greater than 6-month) space-basing. It is concluded that the mixed fleet approach to on-orbit consumables resupply offers significant advantages to the overall logistics requirements.

Eberhardt, Ralph N.

1989-01-01

459

Management of orbital tumors.  

PubMed

Orbital tumors are uncommon. In children, both malignant and benign causes of orbital proptosis necessitate urgent assessment; in many cases, emergent intervention is necessary to avoid blindness. In adults, proptosis is most commonly associated with thyroid orbitopathy. Orbital tumors in adults rarely are characterized by the explosive growth and damage that can occur with childhood lesions. In both age-groups, the evolution of better scanning modalities, such as magnetic resonance imaging with fat saturation and gadolinium enhancement, has improved diagnostic accuracy, especially in patients with loss of vision. In more than 95% of cases, noninvasive techniques yield a correct diagnosis. In patients who require nonsurgical intervention, especially if the diagnosis is uncertain, fine-needle aspiration biopsy has an accuracy that exceeds 95%. Combined-modality therapy has improved the control of and decreased the morbidity associated with several orbital tumors. Surgical advances, such as the ancillary use of the CO2 laser, have enhanced the management of some orbital tumors. PMID:8231272

Char, D H

1993-11-01

460

Arenstorf Orbit JS Model  

NSDL National Science Digital Library

Arenstorf orbits are closed trajectories of the restricted three-body problem. That is, two bodies of masses µ and 1-µ moving in a circular rotation, and a third body of negligible mass moving in the same plane. The computation of these orbits is very sensible to small errors and are a good test for the accuracy of numerical methods for solving Ordinary Differential Equations. This simulation compares the solution of two of these orbits using both a 4th-order fixed step and a 5(4) variable step Runge-Kutta algorithm. The adaptive solver uses an event to find the period of the orbit and stop there. Both the computations of the adaptive solver and the event are done with the step size and the tolerance indicated. The Arenstorf Orbit JS Model was developed using the Easy Java Simulations (Ejs) version 5. It is distributed as a ready-to-run html page and requires only a browser with JavaScript support.

Franciscouembre

2013-08-28

461

Creating High-Harmonic Beams with Controlled Orbital Angular Momentum  

NASA Astrophysics Data System (ADS)

A beam with an angular-dependant phase ? =?? about the beam axis carries an orbital angular momentum of ?? per photon. Such beams are exploited to provide superresolution in microscopy. Creating extreme ultraviolet or soft-x-ray beams with controllable orbital angular momentum is a critical step towards extending superresolution to much higher spatial resolution. We show that orbital angular momentum is conserved during high-harmonic generation. Experimentally, we use a fundamental beam with |?|=1 and interferometrically determine that the harmonics each have orbital angular momentum equal to their harmonic number. Theoretically, we show how any small value of orbital angular momentum can be coupled to any harmonic in a controlled manner. Our results open a route to microscopy on the molecular, or even submolecular, scale.

Gariepy, Genevieve; Leach, Jonathan; Kim, Kyung Taec; Hammond, T. J.; Frumker, E.; Boyd, Robert W.; Corkum, P. B.

2014-10-01

462

Creating high-harmonic beams with controlled orbital angular momentum.  

PubMed

A beam with an angular-dependant phase ? = ?? about the beam axis carries an orbital angular momentum of ?? per photon. Such beams are exploited to provide superresolution in microscopy. Creating extreme ultraviolet or soft-x-ray beams with controllable orbital angular momentum is a critical step towards extending superresolution to much higher spatial resolution. We show that orbital angular momentum is conserved during high-harmonic generation. Experimentally, we use a fundamental beam with |?| = 1 and interferometrically determine that the harmonics each have orbital angular momentum equal to their harmonic number. Theoretically, we show how any small value of orbital angular momentum can be coupled to any harmonic in a controlled manner. Our results open a route to microscopy on the molecular, or even submolecular, scale. PMID:25375710

Gariepy, Genevieve; Leach, Jonathan; Kim, Kyung Taec; Hammond, T J; Frumker, E; Boyd, Robert W; Corkum, P B

2014-10-10

463

Orbit utilization - Current regulations  

NASA Astrophysics Data System (ADS)

It is pointed out that an increasingly efficient use of the geostationary satellite orbit and spectrum is necessary to accommodate the growing number of planned U.S. domestic satellites, as well as those of other countries. Technical efficiency can be maximized by designing satellites in a homogeneous manner which minimizes transmission differences between satellites. However, flexibility is also needed to design domestic satellite facilities to respond to the diverse demands in a competitive market. The Federal Communication Commission (FCC) seeks to achieve a balance between these goals in their domestic satellite policies and regulations. In December 1980, the FCC authorized the construction of some 22 new domestic satellites and the launch of 18 satellites. Attention is given to orbit use policies and reduced orbital spacings.

Lepkowski, R. J.

464

On triangulated orbit categories.  

E-print Network

We show that the category of orbits of the bounded derived category of a hereditary category under a well-behaved autoequivalence is canonically triangulated. This answers a question by A. Buan, R. Marsh and I. Reiten which appeared in their study with M. Reineke and G. Todorov of the link between tilting theory and cluster algebras (closely related to work by Caldero-Chapoton-Schiffler) and a question by H. Asashiba about orbit categories. We observe that the resulting triangulated orbit categories provide many easy examples of triangulated categories with the Calabi-Yau property. These include the category of projective modules over a preprojective algebra of generalized Dynkin type in the sense of Happel-Preiser-Ringel, whose triangulated structure goes back to Auslander-Reiten's work on the representation-theoretic approach to rational singularities.

Bernhard Keller

465

Elliptical vs Circular Orbit  

NSDL National Science Digital Library

Find the contrast between a highly exaggerated earth elliptical orbit and circular orbit depicted in .mov format. It should be mentioned to students that in reality the earth's elliptical orbit around the sun would hardly be noticeable if viewed from this distance. Taken alone, the video could unfortunately perpetuate the misconception that earth sun distance is responsible for the seasons. Still, the video is useful for pointing out that the earth's speed around the sun is not constant, with the earth moving fastest in January and slowest in July. This phenomenon helps explain why summer is longer in the Northern Hemisphere and for the analemma. The animation can be paused and rewound to emphasize important points.

Bob Urschel

466

Butterfly Diagram and Activity Cycles in HR 1099  

E-print Network

We analyze photometric data of the active RS CVn--type star HR 1099 for the years 1975--2006 with an inversion technique and reveal the nature of two activity cycles of 15--16 yr and 5.3$\\pm$0.1 yr duration. The 16 yr cycle is related to variations of the total spot area and is coupled with the differential rotation, while the 5.3 yr cycle is caused by the symmetric redistribution of the spotted area between the opposite stellar hemispheres (flip-flop cycle). We recover long-lived active regions comprising two active longitudes that migrate in the orbital reference frame with a variable rate because of the differential rotation along with changes in the mean spot latitudes. The migration pattern is periodic with the 16 yr cycle. Combining the longitudinal migration of the active regions with a previously measured differential rotation law, we recover the first stellar butterfly diagram without an assumption about spot shapes. We find that mean latitudes of active regions at opposite longitudes change antisymmetrically in the course of the 16 yr cycle: while one active region migrates to the pole, the other approaches the equator. This suggests a precession of the global magnetic field with respect to the stellar rotational axis.

S. V. Berdyugina; G. W. Henry

2007-03-20

467

Mars Orbiter Laser Altimeter  

NASA Technical Reports Server (NTRS)

The objective of this study was to support the rebuild and implementation of the Mars Orbiter Laser Altimeter (MOLA) investigation and to p