... ADP023770. Title : ab-Initio Molecular Dynamics Simulations of Molten Ni-Based Superalloys. Descriptive Note : Conference paper. ...

... Title : Ab-Initio Molecular Dynamics Simulations of Molten Ni-Based Superalloys. Descriptive Note : Conference paper (preprint). ...

... from federally funded research, testing and training ... for Research Development Test and Evaluation ... Title : Ab-Initio Molecular Dynamics Simulations ...

An ab initio centroid molecular dynamics (CMD) method is developed by combining the CMD method with the ab initio molecular orbital method. The ab initio CMD method is applied to vibrational ...

... Static polarizability and second hyperpolarizability tensors have also been computed for a series of polyenes, polyynes and cumulenes by ab initio ...

NMR chemical shifts for an L-alanine molecular crystal are calculated using ab initio plane wave density functional theory. Dynamical effects including anharmonicity may be included by averaging chemical shifts over an ensemble of structural configurations generated using molecular ...

NMR chemical shifts for an L-alanine molecular crystal are calculated using ab initio plane wave density functional theory. Dynamical effects including anharmonicity may be included by averaging chemical shifts over an ensemble of structural configurations generated using molecular ...

control of molecular dynamics; grid methods in the solution of time-dependent problems in quantum mechanics; ab initio calculation of potential energy surfaces and vibronic...

with molecular dynamic simulations in combination with high level correlated ab initio quantum chemical the existing minima in the PES. 2. Ab initio quantum-chemical calculations. The lowest energy minima (within surface analysis by metadynamics. Gibbs energies and ...

materials, (iiii) phonon recycling in lasers, and (iv) phonon-assisted photon absorption in photovoltaics. The theoretical treatments include ab initio and molecular dynamic...

In this work, we present a study on water acetonitrile (AN) mixtures by molecular dynamics ab initio and X-ray diffraction techniques. Comparison of the experimental total G(r) functions of the mixtures with the results of molecular dynamics simulation shows an overall good ...

In this review we present the techniques of ab initio molecular dynamics simulation improved to its current stage where the analysis of existing processes and the prediction of further chemical features and real-world processes are feasible. For this reason we describe the relevant developments in ...

... For example, ab initio quantum chemical calculations when combined with reaction rate theory and kinetics modeling can, in principle, be capable ...

... 3. Ab initio calculations on ammonia, formamide, pyrrole and pyridine. ... The results given in Appendix II for formamide (HCONH2) are typical of the ...

., Montcourier, P., and Fort, P. (1998). RhoG GTPase controls a pathway that independently activates Rac1 and Cdc

................................................................................ 36 5. Glyoxal as a source of organic aerosol

... At present experimental data for ternary Ni-Al-W alloys is not available, and estimates of the accuracy of the Mukai model for liquid density in this ...

... dependent densities in the multicomponent RENE-N4 superalloy, and estimates of the accuracy of the Mukai model for liquid density in this system ...

We present results for the static and dynamic structural properties of undercooled liquid Si, at several temperatures between 1550 K and 1100 K, obtained through orbital-free ab-initio molecular dynamics simulations. The local bond angle distributions show a modest increase in the tetrahedral order upon decreasing ...

The high-pressure induced phase transformation from the zinc blende to rocksalt structure in SiC has been studied by the ab initio molecular dynamics method. The simulations showed that SiC passes through a tetragonal intermediate state before transforming to a monoclinic phase at 160�GPa. The mechanism for this ...

Research completed during the period 1 Feb. 1990 - 28 Feb. 1994 is summarized in the following included papers: 'Ab Initio Statistical Mechanics of Structural Phase Transition'; 'Ab Initio Molecular Dynamics: Analytically Continued Energy Functionals and Insights into ...

We perform ab initio molecular dynamics simulations to study the dissociation of NaCl in water. The potential of mean force (PMF) between the two ions is determined using the constrained-force method. The simulation windows corresponding to the contact and solvent-separated minima, and the transition state in ...

) to applied external force. We first investigate the mechanical response using an ab initio molecular dynamics where the reaction path depends on the strength and nature of the applied force. We first investigate the response of CB under applied forces using steered molecular ...

Electrical conductivity data of Al for the densities from normal to a fraction of normal density and temperatures up to a few thousand Kelvin are important inputs for the hydrodynamic simulations of exploding aluminium foils. We have generated conductivity data of aluminium, by using ab-initio molecular dynamics simulations and the ...

and O�H bond length for a simple water molecule and for water in contact with NaCl surfaces. The resultsAB INITIO MOLECULAR�DYNAMICS SIMULATIONS OF ADSORPTION OF DYE MOLECULES AT SURFACES M. SUGIHARA, H molecules on the NaCl(100) surface. The investigations concentrate on the flat dye molecules trimethin, [C

An approach is developed to enhance sampling for ab initio Monte Carlo and ab initio path integral Monte Carlo calculations of molecular clusters by utilizing an approximate potential as a guide to move in the configuration space more efficiently. The interpolated potential energy obtained by ...

... from federally funded research, testing and training ... for Research Development Test and Evaluation ... of Molecular Modelling and Ab initio Molecular ...

Inelastic neutron scattering, density functional theory, ab initio molecular dynamics, and classical molecular dynamics were used to examine the behavior of nanoconfined water in palygorskite and sepiolite. These complementary methods provide a strong bas...

We present a microscopic model of the interaction and adsorption mechanism of simple organic molecules on SiC surfaces as obtained from ab initio molecular dynamics simulations. Our results open the way to functionalization of silicon carbide, a leading candidate material for bio-compatible devices.

scaling DFT code (see Peter Haynes) Other codes used in TCM for applications ffl CPMD � DFT ab initio? (MT/RN) ffl non�collinear spins in QMC (MT) ffl Pseudopotentials for many�body calculations (Lee, Mostofi, Di'eguez) Applications etc..(CASTEP, CPMD) ffl ab initio molecular ...

,3 While much is known about the properties of the low energy NaCl(001) surface and water covered NaCl(001 the properties of ambient liquid water films remains a challenge for both experiment and first the properties of the hitherto mysterious nanoscale water film that covers NaCl(001). From our ab initio

The recent literature on the determination of minimum energy conformations by ab initio quantum mechanical techniques is reviewed. The availability of computer-coded analytical first and second derivatives of the Hartree-Fock energy makes possible calculations that will be of significant assistance in structure determination of molecules. A short review of ...

We present a formulation of ab initio electronic structure calculations in a finite magnetic field, which retains the simplicity and efficiency of techniques widely used in first principles molecular dynamics simulations, based on plane-wave basis sets and Fourier transforms. In addition we discuss results obtained ...

Ab initio molecular dynamics is used to compute the thermal conductivity of hydrogen at 80 g cm{sup -3} and temperature up to 800 eV. Pressures and ionic structure are compared with orbital-free calculations. Thermal conductivity is evaluated using the Kubo-Greenwood formula and is compared with models currently ...

A biased potential molecular dynamics simulation approach, accelerated molecular dynamics (AMD), has been implemented in the framework of ab initio molecular dynamics for the study of chemical reactions. Using two examples, the ...

A biased potential molecular dynamics simulation approach, accelerated molecular dynamics (AMD), has been implemented in the framework of ab initio molecular dynamics for the study of chemical reactions. Using two examples, the ...

Structural and spectroscopic properties of hydrazine, H(2)N-NH(2), it being a floppy or fluxional molecule in a vacuum, are investigated by means of ab initio molecular dynamics, ab initio path integral molecular dynamics, and ...

The methodology of ab initio molecular dynamics, wherein finite-temperature dynamical trajectories are generated by using forces computed "on the fly" from electronic structure calculations, has had a profound influence in modern theoretical research. Ab ...

The methodology of ab initio molecular dynamics, wherein finite-temperature dynamical trajectories are generated by using forces computed �on the fly� from electronic structure calculations, has had a profound influence in modern theoretical research. Ab ...

For the equilibrium immiscible Fe-Cu system, ab initio calculations using the projector augmented wave method identify the relatively stable structures of the metastable Fe25Cu75 and Fe50Cu50 alloys to be both of fcc and determine their corresponding lattice constants and cohesive energies. Some of the ab initio ...

We have developed an ab initio path integral molecular dynamics method based on the fragment molecular orbital method. This �FMO-PIMD� method can treat both nuclei and electrons quantum mechanically, and is useful to simulate large hydrogen-bonded systems with high accuracy. After a ...

This report briefly summarizes the research developments in ab initio dynamics made possible by this augmentation award to the parent ONR grant. A full description of the research accomplishments will appear in the final technical report of the parent gra...

An ab initio molecular dynamics (MD) simulation technique employing the Born-Oppenheimer approach in the framework of a Gaussian implementation of Kohn-Sham density functional theory is used to study the gas-phase conformational dynamics of an alanine dipeptide analog. It is found that ...

We introduce an ab initio molecular-dynamics method based on the discretized path-integral representation of quantum particles. Fermi statistics is automatically generated by an effective exchange potential. This path-integral molecular-dynamics method is able to simulate electron plasmas at the border of the ...

Mass tensor molecular dynamics method was first introduced by Bennett [J. Comput. Phys. 19, 267 (1975)] for efficient sampling of phase space through the use of generalized atomic masses. Here, we show how to apply this method to ab initio molecular dynamics simulations ...

Mass tensor molecular dynamics method was first introduced by Bennett [J. Comput. Phys. 19, 267 (1975)] for efficient sampling of phase space through the use of generalized atomic masses. Here, we show how to apply this method to ab initio molecular dynamics simulations ...

A comprehensive study of static, dynamic and electronic properties of liquid Al in a thermodynamic state near its triple point was performed by means of 205-particle ab initio molecular dynamics simulations using Kohn-Sham density-functional theory and the Langevin equation of motion. The ...

The theoretical principles underpinning the calculation of infrared spectra for condensed-phase systems in the context of ab initio molecular dynamics have been recently developed in literature. At present, most ab initio molecular ...

The protonation scheme and the hydrogen bond connectivity in the structure of jennite were investigated by ab initio molecular dynamics simulations. The calculated statistics of hydrogen bonds at ambient conditions is consistent with the protonation scheme proposed by Bonaccorsi et al. (2004) based on the bond ...

The relaxation of hot hydrogen atoms upon the dissociative adsorption of H2 on Pd(100) was studied by ab initio molecular dynamics simulations based on density functional theory, modeling the full dissociative adsorption process in a consistent manner. In spite of the nonlinear dependence of every single trajectory ...

We have calculated the melting temperature of tungsten by two ab initio approaches. The first approach can be divided into two steps. In the first step, we simulate a large coexisting solid and liquid system by the classical embedded-atom method potential and obtain an approximate melting temperature. In the second step, we compute the accurate melting ...

The nature of intermolecular interactions between aromatic amino acid residues has been investigated by a combination of molecular dynamics and ab initio methods. The potential energy surface of various interacting pairs, including tryptophan, phenilalanine, and tyrosine, was scanned for determining all the ...

We build an "all-electron" norm-conserving pseudopotential for boron which extends the use of ab initio molecular dynamics simulations up to 50 times the normal density rho0. This allows us to perform ab initio simulations of dense plasmas from the regime where quantum ...

We build an 'all-electron' norm-conserving pseudopotential for boron which extends the use of ab initio molecular dynamics simulations up to 50 times the normal density {rho}{sub 0}. This allows us to perform ab initio simulations of dense plasmas from the ...

The high-pressure induced phase transformation from the zinc blende to rocksalt structure in SiC has been studied by ab initio molecular dynamics. The simulations show that SiC passes through tetragonal and then monoclinic intermediate states before finally forming the rock salt structure at 160 GPa. The mechanism ...

We report herein a series of ab initio simulations of water under both static and shocked conditions. We have calculated the coherent x-ray scattering intensity of several phases of water under high pressure, using ab initio Density Functional Theory (DFT). We provide new atomic scattering form factors for water at ...

... We carried out ab-initio quantum chemical calculations on these energetic cyclic ethers and generated the electrostatic molecular potential contour ...

... The work presented here makes use of state-of- validated mathematical criteria for predicting the-art AIMD simulations as a means for testing the ...

This bibliography lists the following reports: Optimized pseudopotentials, Ab-initio materials science and engineering using the molecular dynamics methods for total energy pseudopotential calculations, Oxygen complexes in Si, The enchanting properties of...

We present a combined experimental and theoretical study on carbon nanodiamonds using Raman and DAC experimentation and ab initio calculations. Our calculations confirm the surface reconstruction to a fullerene-like structure, and indicate compression of ...

The structure and energetics of free radicals, ions, and clusters have been investigated by photoelectron photoion coincidence (PEPICO) and analyzed with the aid of ab initio molecular orbital and statistical theory (RRKM) calculations. The two major them...

The structure and energetics of free radicals, ions, and clusters have been investigated by photoelectron photoion coincidence (PEPICO) and analyzed with ab initio molecular orbital and statistical theory RRKM calculations. In these experiments, molecules...

The predicted high pressure superionic phases of water and HF are investigated via ab initio molecular dynamics. These phases could potentially be achieved through either static compression with heating or through shock compression. We study water at dens...

Atom-centered partial charges are calculated for the Fe-heme in cytochrome P450cam for use in molecular dynamics simulations of polar substrates bound in the active site of the enzyme. Charges are fit to the electrostatic potential produced by ab initio U...

�O liquids11,12 . The calcula- tions were done using the software package VASP24 , which is exceptionally ef

Ab initio molecular dynamics simulations of a recently proposed cobalt-based catalyst for water oxidation provide insight into the properties of protons at the water/oxide interface. Calculations and X-ray absorption spectroscopy data indicate a cubane-like structure of the catalyst, support the occurrence of ...

Density functional theory based ab initio molecular dynamics simulations with explicit inclusion of empirical van der Waals (vdW) corrections of supercritical carbon dioxide have been performed. Significant changes in the intermolecular pair correlation functions of the fluid modeled with the added vdW interactions ...

The decomposition of ethylene carbonate (EC) during the initial growth of solid-electrolyte interphase (SEI) films at the solvent-graphitic anode interface is critical to lithium ion battery operations. Ab initio molecular dynamics simulations of explicit liquid EC/graphite interfaces are conducted to study these ...

High-pressure induced zinc blende to rocksalt phase transition in GaN has been investigated by ab initio molecular dynamics method to characterize the transformation mechanism at the atomic level. It was shown that at 100 GPa GaN passes through tetragonal and monoclinic states before rocksalt structure is formed. ...

The decomposition of ethylene carbonate (EC) during the initial growth of solid-electrolyte interphase (SEI) films at the solvent-graphitic anode interface is critical to lithium ion battery operations. Ab initio molecular dynamics simulations of explicit liquid EC/graphite interfaces are conducted to study these ...

The framework of ab initio density-functional theory (DFT) has been introduced as a way to provide a seamless connection between the Kohn-Sham (KS) formulation of DFT and wave-function based ab initio approaches [R. J. Bartlett, I. Grabowski, S. Hirata, and S. Ivanov, J. Chem. Phys. 122, 034104 (2005)]. Recently, ...

Born-Oppenheimer ab initio QM/MM molecular dynamics simulation with umbrella sampling is a state-of-the-art approach to calculate free energy profiles of chemical reactions in complex systems. To further improve its computational efficiency, a mass-scaling method with the increased time step in MD simulations has ...

A new method of incorporating ab initio theoretical data dynamically into the gas-phase electron diffraction (GED) refinement process has been developed to aid the structure determination of large, sterically crowded molecules. This process involves calculating a set of differences between parameters that define the positions of ...

Due to recent advances in methods and computers, the accuracy of ab calculations has reached a point

Two approaches for directly computing a molecular heat of formation based on sophisticated ab initio

... nightmares for traditional quantum chemical approaches for optimizing structures of such ... an unbiased manner with ab initio forces. ...

The quantum dynamics of the rotational quenching of the Mg24H+(X1?+) molecular cation interacting with He4(1S) as a buffer gas, at relative temperatures ranging from 1 K down to millikelvins, is described by accurate close coupling scattering calculations on an ab initio potential energy surface. The efficiency of ...

We have performed extensive ab initio and classical MD simulations of benzene in water in order to examine the unique solvation structures that are formed. Qualitative differences between classical and ab initio MD simulations are found and the importance of various technical simulation parameters is examined. Our ...

In this work we show how the ab initio determination of van der Waals coefficients within time-dependent density functional theory can be used to build efficient and accurate atomistic models that describe the long-range interactions of proteins with other proteins and of proteins with semi-conducting surfaces. The model parameters are fitted so that they ...

The dimerization of formamide (FMA) has been investigated by matrix isolation spectroscopy, static ab initio calculations, and ab initio molecular dynamics (AIMD) simulations. Comparison of the experimental matrix IR spectra with the ab ...

An ab initio study based on local-density-functional (LDF) theory is presented for the chemisorption of hydrogen on the Pd(111) surface. Our calculation uses the Vienna ab initio molecular-dynamics program (VAMP) based on (i) finite-temperature LDF, (ii) exact calculation of the electronic ...

Ab initio molecular dynamics (MD) method has been used to study high pressure-induced phase transformation in BeO based on the local density approximation (LDA) and the generalized gradient approximation (GGA). Both methods show that the wurtzite (WZ) and zinc blende (ZB) BeO transforms to the rocksalt (RS) ...

Simulations of the tetravalent group IV metal ions, Ge(IV), Sn(IV), and Pb(IV), in aqueous solution were performed using ab initio quantum mechanical charge field molecular dynamics (QMCF MD). The process of hydrolysis, which occurred for each of the metal ions, was analyzed in terms of the time evolution of ...

Social permutation invariant coordinates are introduced describing the bond network around a given atom. They originate from the largest eigenvalue and the corresponding eigenvector of the contact matrix, are invariant under permutation of identical atoms, and bear a clear signature of an order-disorder transition. Once combined with ab initio ...

We have simulated exchange of inner-sphere and bulk water molecules for different sizes of Al3+(aq) clusters, Al(H2O)63+ + nH2O for n = 0, 1, 6, or 12, with ab initio and molecular dynamics simulations, in order to understand how robust the ab initio method is for ...

in Molecular Wires Alexander B. Pacheco and Srinivasan S. Iyengar Department of Chemistry, Indiana University through molecular wires. The simultaneous dynamics of electrons and nuclei in the wire is coupled are common tools for studying such system. � The system consists of a molecular wire system sandwiched

The interaction of hydrogen with palladium surfaces represents a model system for the study of the adsorption and absorption at metal surfaces. Theoretical gas-surface dynamics studies have usually concentrated on the adsorption dynamics on clean surfaces. Only recently has it become possible, based on advances in electronic structure codes and ...

The near-UV absorption spectra of barnase double-point mutants are calculated using a combination of molecular dynamics and ab initio techniques. The atoms of the fluorescent probes are placed in a cloud of point charges, generated by molecular dynamics simulations. ...

The near-UV absorption spectra of barnase double-point mutants are calculated using a combination of molecular dynamics and ab initio techniques. The atoms of the fluorescent probes are placed in a cloud of point charges, generated by molecular dynamics simulations. ...

Molecular dynamics (MD) is a powerful tool to probe the thermodynamic and kinetic properties of solid, glass and liquid phases. In classical molecular dynamics (CMD), empirical models are used to describe the force by considering bond, bend and dihedral angle contributions with parameters fitted to experimental ...

We have applied the ab initio path integral molecular dynamics simulation to study hydronium ion and its isotopes, which are the simplest systems for hydrated proton and deuteron. In this simulation, all the rotational and vibrational degrees of freedom are treated fully quantum mechanically, while the potential ...

We have applied the ab initio path integral molecular dynamics simulation to study hydronium ion and its isotopes, which are the simplest systems for hydrated proton and deuteron. In this simulation, all the rotational and vibrational degrees of freedom are treated fully quantum mechanically, while the potential ...

The potential of mean force for the dissociation of a Ca-Cl ion pair in water is calculated from ab initio molecular dynamics simulations. The constraint-force method is employed to enhance sampling over the entire range of the reaction coordinate (Ca-Cl distance) from 2.2 to 6.5 A?. Particular attention is paid to ...

The potential of mean force for the dissociation of a Ca-Cl ion pair in water is calculated from ab initio molecular dynamics simulations. The constraint-force method is employed to enhance sampling over the entire range of the reaction coordinate (Ca-Cl distance) from 2.2 to 6.5 A?. Particular attention is paid to ...

Incoherent inelastic neutron scattering is used to probe the effects of dihydrogen bonding on the vibrational dynamics in the molecular crystal of ammonia borane. The thermal neutron energy loss spectra of (11)B enriched ammonia borane isotopomers ((11)BH(3)NH(3), (11)BD(3)NH(3), and (11)BH(3)ND(3)) are presented and compared to the vibrational power ...

The ab initio molecular-dynamics formalism of Car and Parrinello is extended to preserve the locality of the orbitals. The supplementary term in the Lagrangian does not affect the nuclear dynamics, but ensures "on the fly" localization of the electronic orbitals within a periodic supercell in the Gamma-point ...

The ab initio molecular-dynamics formalism of Car and Parrinello is extended to preserve the locality of the orbitals. The supplementary term in the Lagrangian does not affect the nuclear dynamics, but ensures ``on the fly'' localization of the electronic orbitals within a periodic supercell in the ?-point ...

In a previous contribution, we outlined a method for predicting (hydr)oxy-acid and oxide surface acidity constants based on three main factors: bond valence, Me O bond ionicity, and molecular shape. Here, electrostatics calculations and ab initio molecular dynamics simulations are used to ...

We performed a comprehensive study of the static, dynamic, and electronic properties of liquid Pb at T=650K , ?=0.0309�?3 by means of 216-particle ab initio molecular dynamics simulations based on a real-space implementation of pseudopotentials constructed within density-functional theory. ...

We present results for several structural and dynamical properties of the liquid Li1-xNax alloy. The study has been carried out by means of the orbital-free ab initio molecular dynamics method, combined with local ionic pseudopotentials constructed within the same framework. We obtain good ...

The static and dynamic properties of liquid Sn at two di?erent thermodynamic states have been studied from the Orbital Free Ab-Initio Molecular Dynamics (OFAIMD) simulation method. This method is based on the density functional theory (DFT) of Hohenberg and Kohn. The exchange and correlation interaction is ...

We present results for a comprehensive study of the static, dynamic and electronic properties of liquid Pb near melting by means of 216-particle ab initio molecular dynamics simulations based on a real-space implementation of pseudopotentials constructed within density-functional theory. The ...

Ab initio molecular dynamics simulations are a powerful tool for examining liquids and amorphous materials; however, such simulations are often computationally intensive. We present a molecular dynamics method that dramatically reduces the computational load using a new ...

Pairing of guanidinium moieties in water is explored by molecular dynamics simulations of short arginine-rich peptides and ab initio calculations of a pair of guanidinium ions in water clusters of increasing size. Molecular dynamics simulations show that, in an aqueous ...

Terahertz spectroscopy, which investigates the electromagnetic spectrum of samples between 0.1 and 10 THz, allows not only for exploration of molecular structures but also of molecular dynamics. One difficulty in performing THz spectroscopy is that the data can be noisy and difficult to interpret. Ab ...

The conformational preference of the glycosidic linkage of methyl-?-mannose was studied in the gas phase and in aqueous solution by ab initio calculations, and by molecular dynamics (MD) and Car-Parrinello molecular dynamics (CPMD) simulations. MD simulations were performed ...

We report here a direct ab initio molecular dynamics study of the p-/o-H2+HOC+ reaction on the basis of the accurate SAC-MP2 potential energy surface. The quasi-classical trajectory method was employed. This work largely focuses on the study of reaction mechanisms. A roaming mechanism was identified for this ...

An all-atom force field for 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) is presented. The classical intermolecular interaction potential for TATB is based on single-point energies determined from high-level ab initio calculations of TATB dimers. The newly developed potential function is used to examine bulk crystalline TATB via ...

The gas phase reaction of Th(+) with H(2)O to produce HThO(+) + H and ThO(+) + H(2) was investigated using density functional theory and coupled cluster methods. RRKM calculations of the branching ratio favor the H atomic elimination channel in disagreement with experiment. Ab initio classical trajectory calculations were carried out to obtain a better ...

Classical molecular dynamics (CMD) calculations are fast but are heavily dependent on the potential feasibility. On the other hand, first-principles (ab initio) molecular dynamics (AIMD) does not use any empirical knowledge, but can be extremely time consuming. As both ...

Momentum imaging experiments on dissociative electron attachment to the water molecule are combined with ab initio theoretical calculations of the angular dependence of the quantum mechanical amplitude for electron attachment to provide a detailed picture of the molecular dynamics of dissociation attachment via ...

Momentum imaging experiments on dissociative electron attachment (DEA) to a water molecule are combined with ab initio theoretical calculations of the angular dependence of the quantum mechanical amplitude for electron attachment to provide a detailed picture of the molecular dynamics of dissociation attachment via ...

Molecular dynamics simulations were performed using a modified amoeba force field to determine hydration and dynamical properties of the divalent cations Ca2+ and Mg2+. The extension of amoeba to divalent cations required the introduction of a cation specific parametrization. To accomplish this, the Thole polarization damping model ...

Molecular dynamics simulations were performed using a modified amoeba force field to determine hydration and dynamical properties of the divalent cations Ca2+ and Mg2+. The extension of amoeba to divalent cations required the introduction of a cation specific parametrization. To accomplish this, the Thol� polarization damping model ...

A new �on the fly� method to perform Born-Oppenheimer ab initio molecular dynamics (AIMD) simulations is presented. Inspired by Ehrenfest dynamics in time-dependent density functional theory, the electronic orbitals are evolved by a Schr�dinger-like equation, where the orbital time ...

Large-scale ab initio molecular dynamics simulations of ion-solid interactions in SiC reveal that significant charge transfer occurs between atoms, and defects can enhance charge transfer to surrounding atoms. The results demonstrate that charge transfer to and from recoiling atoms can alter the energy barriers and ...

Ab initio molecular dynamics (AIMD) simulations are performed for studying the S0-->T1 excitation dynamics of psoralen compounds; namely, nonsubstituted psoralen, 5-methoxypsoralen (5-MOP), and 8-methoxypsoralen (8-MOP). The density functional theory calculations at the B3LYP/D95V level are ...

The importance of quantum effects as well as the accuracy of the ab initio-based polarizable TTM2.1-F force field in describing liquid water are quantitatively assessed by a detailed analysis of the temperature dependence of several thermodynamic and dynamical properties computed using the path-integral molecular ...

The accurate molecular simulation of many hydrated chemical systems, including clay minerals and other phyllosilicates and their interfaces with aqueous solutions, requires improved classical force field potentials to better describe structure and vibrational behavior. Classical and ab initio molecular ...

An aqueous glycine solution is studied with ab initio molecular dynamics to investigate the structural aspects of the different solvation shells within the zwitterion and their impact on the infrared spectrum. The individual contributions to the total IR spectrum from glycine and solvation water are decomposed ...

The molecular probe N-methyl-6-quinolone (MQ) gives experimental access to its local chemical environment, e.g. inside a biomolecule. Using ab initio molecular dynamics (MD), it is possible to simulate the time evolution of the Stokes shift as a function of the actual atomistic coupling to the ...

We have developed new force field and parameters for copper(I) and mercury(II) to be used in molecular dynamics simulations of metalloproteins. Parameters have been derived from fitting of ab initio interaction potentials calculated at the MP2 level of theory, and results compared to experimental data when ...

The use of discrete variable representation (DVR) basis sets within ab initio molecular dynamics calculations allows the latter to be performed with converged energies and, more importantly, converged forces. In this paper, we show how to carry out ab initio ...

We have tested approaches for molecular-dynamics simulations of the ion properties in high-energy-density matter. The scheme incorporates quantum corrections within the potentials used in the classical molecular-dynamics simulation. Thus, a significantly larger number of particles in the simulation box as in ab ...

The pressure dependence of the static and dynamic properties of liquid boron oxide, B2O3 , is studied by ab initio molecular dynamics simulations. Planar BO3 units are found to be scarcely deformed under pressures up to about 3 GPa. Under further compression, the number of tetrahedral BO4 ...

The hydrogen storage is still a challenge for mobile applications. The diffusion of hydrogen in solids is considered as a general model system but there is limited knowledge available for the dynamics of hydrogen in complex hydrides. In this letter, we present a systematic approach to study the hydrogen-deuterium exchange in bulk LiBH4 based on ab ...

Structures of the ground state pyrrole-(H2O)n clusters are investigated using ab initio calculations. The charge-transfer driven femtosecond scale dynamics are studied with excited state ab initio molecular dynamics simulations employing the ...

Ab initio molecular orbital calculations on phosphites, protonated phosphites, and protonated phosphates reveal important stereoelectronic effects. In the phosphites, an antiperiplanar lone pair on oxygen to the phosphite lone pair raises the energy of th...

The number of ab initio molecular electronic calculations has increased dramatically in the last few years. Both the practitioners and other interested students of the results of the calculations have found it increasingly difficult to determine the prese...

An ab initio model is developed for the potentials in ionic molecular solids in which the electron covalenc within the molecular ions substantially affects the interionic interactions. By treating the intermolecular and intramolecular interactions on the ...

and compression cycles is studied. Ab-initio local- spin-density functional based molecular dynamics simula- tions the Born-Oppenheimer Local-Spin-Density Functional Molecular-Dynamics (BO-LSD-MD) method [28] in inves confining the electrons in the wire is short-ranged (as also found in recent local density ...

Studies of ring-saturated pyrimidine base lesions are used to illustrate an integrated modeling approach that combines quantum-chemical calculations with molecular dynamics simulation. Electronic-structure calculations on the lesions in Isolation reveal s...

The aim of this thesis is to study metallic sodium clusters by numerical simulation. We have developed two ab initio molecular dynamics programs within the formalism of density functional theory. The first is based on the semi- classical extended Thomas-F...

: the four bead model A(1-40) and A(1-42) oligomer formation -four-bead protein model with amino acid of electrostatic interactions in A oligomer formation: A discrete molecular dynamics study,'' in preparation: The DMD code has been generalized to account for assembly studies of two different peptides. Oligomer

. All ab initio molecular dynamics simulations were performed with the CPMD program.13 Density func and Ernzerhof.14 Core electrons on all atoms were represented by norm- conserving pseudopotentials15). 13 J. H�utter et al., CPMD, Copyright IBM Z�urich Research Laboratory and MPI f�ur Festk

The Born-Oppenheimer approximation divides the problem of quantum molecular dynamics into two familiar problems: (1) solution for the electronic wave functions for a given instantaneous arrangement of ions and (2) the motion of the atomic cores under the ...

... Molecular Orbital Studies on Nucleoside Antibodies VIII, Ab Initio Calculation of Cubic Force Constants in Formamide Monomer, Formamide Dimer ...

... Corporate Author : NATIONAL STANDARD REFERENCE DATA SYSTEM. ... observable properties including the total energy, dissociation energy ...

The dynamics of the ethylene molecule in femtosecond laser pulses is studied as a function of the laser parameters using an ab initio time-dependent approach, called nonadiabatic quantum molecular dynamics. We predict that, by choosing different femtosecond pulses with well-defined excitation ...

The four possible mechanisms of ring closure in dioxin formation from chlorophenols are studied using ab initio molecular dynamics, within generalized gradient approximation. Free energy barriers, derived as the potential of mean constraint force, directly lead to a static approximation for the transition rates. We ...

Using ab initio molecular dynamics we investigate the electronic and lattice structure of AFe2As2 (A=Ca,Sr,Ba) under pressure. We find that the structural phase transition (orthorhombic to tetragonal symmetry) is always accompanied by a magnetic phase transition in all the compounds while the nature of the ...

The structural and bonding properties of liquid boron oxide are studied by ab initio molecular dynamics simulations. It is seen that, even in the liquid state, boron atoms are predominantly threefold coordinated to oxygen atoms, and most of oxygen atoms bridge two adjacent boron atoms. The neighboring atoms are ...

The initial stages of NaCl dissolution in liquid water have been examined with state-of-the-art ab initio molecular dynamics and free energy sampling techniques. Our simulations reveal a complex multi-step process triggered by the departure of Cl ions from the lattice, with a well-defined intermediate state wherein ...

Potassium ion in water plays a very important role in chemistry and biology. In this paper, we investigated the hydration structure and coordination of K(+) solvation in water at 300 and 450 K using ab initio Car-Parrinello molecular dynamics. The K(+)-oxygen radial distribution function indicated that the ...

An overview of the parallel algorithms for ab initio molecular dynamics (AIMD) used in the NWChem program package is presented, including recent developments for computing exact exchange. These algorithms make use of a two-dimensional processor geometry proposed by Gygi et al for use in AIMD algorithms. Using this ...

The local atomic structure and elastic properties of two series of multicomponent amorphous steels--with and without phosphorus addition--have been investigated by ab initio molecular dynamics. A comparison of neutron pair-distribution functions allowed the difference in local atomic organization for these two ...

We used a variational approach adapted to a quantum molecular-dynamics code to determine the best reference potential for warm dense aluminum. This ab initio variational approach was based on the Gibbs-Bogolyubov inequality. We used many-body reference systems interacting through inverse-power-law potentials, among which the Coulomb ...

The structural environment of Mg in a K-bearing silicate glass of composition K2MgSi3O8 is investigated by x-ray absorption near-edge structure (XANES) spectroscopy at the Mg K-edge. XANES calculations are performed using a plane-wave electronic structure code, and a structural model obtained by classical molecular dynamics coupled to ...

The structural environment of Mg in a K-bearing silicate glass of composition K(2)MgSi(3)O(8) is investigated by x-ray absorption near-edge structure (XANES) spectroscopy at the Mg K-edge. XANES calculations are performed using a plane-wave electronic structure code, and a structural model obtained by classical molecular dynamics coupled to ...

Collision processes between a single gold atom and a gold cluster are investigated by means of ab initio techniques. The targets we consider are minimum energy 13 gold atom clusters. The kinetic energy of the projectile and its impact parameter are chosen within a range such that the three regimes we are mainly interested in studying (fusion, scattering ...

The atomic and electronic structure of uniformly and nonuniformly mixed Au-Co nanowires have been studied using the ab initio molecular dynamics method. The effect of elastic stretching/contraction deformations on the stability and electronic properties of mixed Au-Co nanowires has been studied. It is established ...

The structural and electronic properties of molten CuI are studied by means of ab initio molecular-dynamics simulations. From the first-peak positions of the partial pair distribution functions, we confirm that the nearest-neighbor distance for Cu-Cu pair is almost the same as that for Cu-I pair in spite of the correlation between the ...

A direct calculation of the coherent x-ray scattering spectrum of liquid water under ambient conditions is presented using ab initio density functional theory. The experimental data are compared with the calculated x-ray scattering spectra retrieved from the trajectories of two Car-Parrinello molecular dynamics ...

The microscopic mechanism of the metallization of liquid selenium under pressure is studied by ab initio molecular dynamics simulations. From the obtained electronic properties, such as the electronic density of states and the bond-overlap population, the pressure-induced metallization is found to be completed at a ...

Using ab initio molecular dynamics simulations, the local atomic structure and electronic properties of supercooled liquid Si (l-Si) at different temperatures from 1700 to 1100 K were studied. Our calculated coordination numbers present no obvious change in the temperature range investigated. Our results indicate ...

Proton dissociation and transfer were examined with ab initio molecular dynamics (AIMD) simulations of carbon nanotubes (CNT) functionalized with perfluorosulfonic acid (-CF(2)SO(3)H) groups with 1-3 H(2)O/SO(3)H. The CNT systems were constructed both with and without fluorine atoms covalently bound to the walls to ...

Al bombardment induced structural changes in ?-Al2O3 (R-3c) and ?-Al2O3 (Fd-3m) were studied using ab initio molecular dynamics. Diffusion and irradiation damage occur for both polymorphs in the kinetic energy range from 3.5 to 40 eV. However, for ?-Al2O3(001) subplantation of impinging Al causes significantly ...

We describe the construction of a multi-phase equation of state for carbon at extreme pressures based on ab initio electronic structure calculations of two solid phases (diamond and BC8) and the liquid. Solid-phase free energies are built from knowledge of the cold curves and phonon calculations, together with direct ab ...

We present a general method for tracking molecular relaxation along different pathways from an excited state down to the ground state. We follow the excited state dynamics of cytosine pumped near the S(0)-S(1) resonance using ultrafast laser pulses in the deep ultraviolet and probed with strong field near infrared pulses which ionize and dissociate the ...

We present a general method for tracking molecular relaxation along different pathways from an excited state down to the ground state. We follow the excited state dynamics of cytosine pumped near the S0-S1 resonance using ultrafast laser pulses in the deep ultraviolet and probed with strong field near infrared pulses which ionize and dissociate the ...

We present a first ab initio investigation of the electron phonon coupling (EPC) of molecular metallic hydrogen with a Cmca structure based on the linear-response approach. This molecular metallic hydrogen with overlapping bands has an elastic instability at lower pressures (<300 GPa), but stabilizes ...

Molecular dynamics simulations of NO-doped Ar solid upon Rydberg photoexcitation of the impurity have been carried out taking into account angular dependent potential energy surfaces (PESs) in the ground and excited states. To go beyond isotropic potentials simulations, the effects of anisotropy of potentials on the structure, ...

We calculate the static structure factor of dense multi-component plasmas. Large scale ab initio finite-temperature DFT molecular dynamics simulations are performed in order to cover the region where a consistent quantum treatment for the electrons is inevitable. Especially, the behavior at small wave numbers k can ...

We report the e?ects of system size on melting of dense sodium at about 100 GPa. We have performed systematic ab initio molecular-dynamics (MD) simulations with the number of atoms at most 250 for bcc and 256 for fcc structures based on 3s-valence-electron model and 2p3s-valence-electron model. We have shown that the inner-core 2p ...

The structure dependent magnetism and intermixing characteristics of Ti/Fe(001) thin films were investigated using molecular dynamics simulations and ab initio calculations. Through density functional theory based ab initio calculations, sharply decreased demagnetization ...

We have studied the liquid surface of sodium with extensive ab initio molecular dynamics simulations based on ensemble density-functional theory. We find clear evidence of layering in the direction perpendicular to the surface that persists to temperatures more than 100 K above the melting point. We also observe ...

The adsorption energies of methane and ethane in zeolites are investigated with ab initio molecular orbital theory and density functional theory. In this work we have used zeolite cluster models containing two, three, and five tetrahedral (Si, Al) atoms a...

The detailed molecular structure of methyl phosphonate, the simplest phosphorus ester, was determined by ab initio quantum-chemical calculations in a variety of basis sets. Computed properties include the optimized structure, dipole moment, number and rel...

A new method called adaptive force matching (AFM) has been developed that is capable of producing high quality force fields for condensed phase simulations. This procedure involves the parametrization of force fields to reproduce ab initio forces obtained from condensed phase quantum-mechanics/molecular-mechanics (QM/MM) calculations. ...

A theory of quantum electron wavepacket dynamics that nonadiabatically couples with classical nuclear motions in intense optical fields is studied. The formalism is intended to track the laser-driven electron wavepackets in terms of the linear combination of configuration-state functions generated with ab initio ...

We calculate the dynamic structure factor S(k,?) of liquid Ge (l-Ge) at temperature T=1250 K, and of amorphous Ge (a-Ge) at T=300 K, using ab initio molecular dynamics. The electronic energy is computed using density-functional theory, primarily in the generalized gradient approximation, ...

The profiles of the potential of mean force for the Cl^- - H₃O⁺ pair, as predicted by two ab initio models, are determined by constraint molecular dynamics simulation at a near-critical condition. The corresponding association constants are then ...

The structural stability of protonated methane \\(CH +5\\) and acetylene \\(C2H +3\\) has been investigated with ab initio molecular dynamics. In CH +5, the hydrogen atoms execute large amplitude pseudorotational motions. The hydrogen migrations are not disturbed by complexation with a hydrogen molecule. In ...

deposition on Al(111) - STM FOV: 23 nm. Ti/Al(111) deposited at 400 K. #12;10 FT-IR Spectroscopy - atomic H, time-resolved, high-pressure. � X-ray microprobe � IR micro-spectroscopy � Surface microscopy & energetics. Ab-initio molecular dynamics - surface dynamics. FT-infrared reflection spectroscopy - ...

In this paper, we generate a-Ge2Sb2Te5 models via ab initio molecular dynamic simulations, track the dynamic changes of network at 500 K, and correlate the structural changes in the course of the simulation with changes in electronic structure. Considerable fluctuations of the electronic gap ...

Alacranite, As(8)S(9), has been studied by a combined approach based on micro-Raman measurements and ab initio molecular dynamics simulations, with the Car-Parrinello method. The structure of this arsenic sulfide mineral consists of an ordered packing of As(4)S(4) and As(4)S(5) cagelike molecules, with a topology ...

The reduced-added Green's function technique in the quantum defect theory combines the advantages of analytical and ab initio methods in calculating frequency-dependent (dynamic) polarizabilities of atoms and molecules, providing an exact account for the high-excited and continuum electronic states. In the present paper this ...

We investigate the capabilities of dynamic compression by intense heavy ion beams to yield information about the high pressure phases of hydrogen. Employing ab initio simulations and experimental data, a new wide range equation of state for hydrogen that covers solid, fluid, gas and plasma phases has been constructed for our ...

The ab initio atom-centered density matrix propagation (ADMP) method has been employed to study the dynamics of protonated water clusters of various sizes. An interesting result that hints at the possible amphiphilicity of the hydronium ion is detected. The hydrated proton tends to reside on the surface of the water clusters studied, ...

Intermolecular interaction potentials of the trifluoromethane dimer in 15 orientations have been calculated using the Hartree-Fock (HF) self-consistent theory and the second-order M�ller-Plesset (MP2) perturbation theory. Single point energies at important geometries were also calibrated by the coupled cluster with single and double and perturbative triple excitation [CCSD(T)] calculations. We ...

This study involves: Ab-initio crystal orbitals and polymer orbitals; Ab-initio coupled cluster program; Ab-initio quantum chemical calculations and electrostatic molecular potential contour maps for cationic polymerization; Prediction of crystal density;...

The nuclear magnetic resonance chemical shift is one of the most powerful properties available for structure determination at the molecular level. A review of advances made in the ab initio calculation of chemical shielding during the past five years is presented. Specifically, progress in the areas including the effects of an unpaired ...

The structure of a Zr{sub 73}Pt{sub 27} metallic glass, which forms a Zr{sub 5}Pt{sub 3} (Mn{sub 5}Si{sub 3}-type) phase having local atomic clusters with distorted icosahedral coordination during the primary crystallization, has been investigated by means of x-ray diffraction and combining ab initio molecular-dynamics (MD) and reverse ...

We report herein ab initio molecular dynamics simulations of graphite under shock compression in conjunction with the multiscale shock technique. Our simulations reveal that a novel short-lived layered diamond intermediate is formed within a few hundred of femtoseconds upon shock loading at a shock velocity of 12 ...

The potential energy surfaces (PESs) of the two lowest excited singlet states of furan [correlating with the Rydberg 1A2(3s) and valence 1B2(V) states at the C2v ground-state molecular configuration] have been studied in some detail with regard to the photoinduced ring-opening reaction. The surfaces have been characterized in terms of their stationary points and points of ...

Quantum-mechanical molecular dynamics have been used to investigate structural and physical properties of the 1/1 approximant of the icosahedral Al-Cu-Fe quasicrystal. Particular local structural arrangements of atoms, referred to here as clusters, have been analyzed with respect to their properties within the crystal structure. Artificial strain and ...

Using a quasi-ab initio molecular-dynamics method we have studied two-dimensional (2D) versus three-dimensional (3D) structures in Co clusters deposited on Cu(001) finding that the magnetism plays a relevant role. For the magnetic Co25 supported cluster, the influence of such a 2D to 3D structural change on the magnetic properties ...