Calculation of ab initio frequencies from short time classical trajectories

1989 ◽  
Vol 154 (4) ◽  
pp. 391-395 ◽  
Author(s):  
D.W. Noid ◽  
J.E. Bloor ◽  
M. Spotswood ◽  
M.L. Koszykowski
Keyword(s):  
Ab Initio ◽  
Classical Trajectories ◽  
Short Time

SEMI-CLASSICAL PROPAGATION AND SPECTRAL ANALYSIS IN THE H- ION INTERACTING WITH A METALLIC SURFACE

2005 ◽  
Vol 04 (02) ◽  
pp. 357-372
Author(s):  
JOHN JAIRO ZULUAGA ◽  
JORGE MAHECHA ◽  
EUGENE CHULKOV
Keyword(s):  
Spectral Analysis ◽  
Local Potential ◽  
Metallic Surface ◽  
Electron Interaction ◽  
Time Signal ◽  
Filter Diagonalization ◽  
Resonant States ◽  
Classical Trajectories ◽  
Short Time ◽  
Harmonic Inversion

A semi-classical propagator method combined with harmonic inversion of short time signals is used to find the resonant states of an electron interacting with a hydrogen atom near a metallic surface. The atom-electron interaction corresponds to one electron in the presence of a neutral compact core, which can be described by a simple local potential proposed by Cohen. On the other hand, the electron-surface interaction is described by a model proposed by Jennings, the so-called Jelly Model, or by a more realistic local potential that takes into account the shell structure of the metal. A semi-classical propagator approach, proposed by Herman and Kluk, is used to calculate an approximation to the autocorrelation function A(t) = <ψt|ψ0> entirely in terms of classical trajectories. A filter-diagonalization method for harmonic inversion of the complex time signal A(t) is applied to extract the resonances. We verified that the spectral analysis of the signal obtained by semi-classical methods gives satisfactory numerical results for the position and width of the lowest lying resonances.

Irradiation-induced ordering in Pt-Cu alloy focusing on Pt7Cu

2015 ◽  
Vol 1760 ◽  
Author(s):  
T. Nagase ◽  
Y. Seno ◽  
H. Yasuda ◽  
H. Mori
Keyword(s):  
Ab Initio ◽  
Density Functional ◽  
Alloy System ◽  
Functional Theory ◽  
High Voltage Electron Microscopy ◽  
Voltage Electron ◽  
Cu Alloy ◽  
Gcmc Simulation ◽  
Phase Intermetallic ◽  
Short Time

ABSTRACTThe existence of Pt7Cu ordering phase (intermetallic compound) was investigated by ab initio calculations and high voltage electron microscopy (HVEM) focusing on irradiation-induced ordering. The Pt7Cu ordering phase (cF32, prototype Ca7Ge) was predicted at 0 K through density functional theory (DFT), and using cluster expansion (CE) method and grand canonical Monte Carlo (GCMC) simulation, the ordering temperature of fcc-based Pt7Cu ordering phase was estimated to be above room temperature. The formation of Pt7Cu ordering phase was confirmed by a short-time irradiation for 3.6×103 s at 600 K. MeV electron irradiation can reduce drastically the annealing time for the ordering in the Pt-Cu alloy system, indicating that the combination of the prediction by ab initio calculations and HVEM can offer the unique opportunity to investigate the existence of ordering phase in alloys.

Ab initio classical trajectories on the Born–Oppenheimer surface: Updating methods for Hessian-based integrators

1999 ◽  
Vol 111 (19) ◽  
pp. 8773-8777 ◽  
Author(s):  
Vebjørn Bakken ◽  
John M. Millam ◽  
H. Bernhard Schlegel
Keyword(s):  
Ab Initio ◽  
Classical Trajectories

Quasiclassical trajectory study of the CH2 + O2 reaction

1987 ◽  
Vol 52 (2) ◽  
pp. 535-540
Author(s):  
Ján Urban ◽  
Viliam Klimo ◽  
Jozef Tiňo
Keyword(s):  
Ab Initio ◽  
Rate Constant ◽  
Dynamic Characteristics ◽  
Atomic Oxygen ◽  
Oxygen Formation ◽  
Classical Trajectories

The reaction of atomic oxygen formation from methylene and O2 reactants was studied on the LEPS surface with Sato parameters determined by fitting ab initio points of the triplet reaction hypersurface. Besides the rate constant obtained from the analysis of classical trajectories, dynamic characteristics of the reaction have been determined.

scholarly journals Ab initio structure determination of [Eu5(C2H4O2)6(CH3CO2)3] n by X-ray powder diffraction

2018 ◽  
Vol 74 (6) ◽  
pp. 592-597 ◽  
Author(s):  
Amal Abdallah ◽  
Souad Ammar ◽  
Voraksmy Ban ◽  
Romain Sibille ◽  
Michel Francois
Keyword(s):  
Ab Initio ◽  
Powder Diffraction ◽  
Metal Organic Framework ◽  
Porous Metal ◽  
Optimization Methods ◽  
Cubic Symmetry ◽  
Synchrotron Powder Diffraction ◽  
Metal Organic ◽  
Ab Initio Structure ◽  
Short Time

The compound [Eu5(C2H4O2)6(CH3CO2)3] n was synthesized by dissolving acetate europium salt in ethylene glycol solvent and heating under reflux for a short time. Its structure was solved ab initio from synchrotron powder diffraction data using optimization methods in direct space. The compound has a very large unit-cell volume of 23679 Å3 and the highest centred cubic symmetry space group, Ia{\bar 3}d (No. 230). The porous metal–organic framework structure is similar to those usually observed in zeolites, with pores volumes of 82 Å3, which is of potential interest for gas storage.

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