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General harmonic approximation for time‐dependent molecular dynamics
Author(s) -
Deumens E.,
Öhrn Y.
Publication year - 2009
Publication title -
international journal of quantum chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.484
H-Index - 105
eISSN - 1097-461X
pISSN - 0020-7608
DOI - 10.1002/qua.560360807
Subject(s) - born–huang approximation , random phase approximation , muffin tin approximation , linear approximation , quadratic equation , born approximation , wave function , high frequency approximation , equations of motion , gaussian , physics , phase (matter) , electron , classical mechanics , statistical physics , quantum mechanics , mathematics , nonlinear system , mathematical analysis , approximation error , scattering , geometry
The linear approximation to TDVP equations for the complete molecular system is used to derive equations of motion for the electrons and the nuclei in the random phase approximation (RPA). Definitions of the relevant matrix elements in terms of nuclear gradients and hessians of the energy are given. The linear approximation to the evolution equations corresponds to a Gaussian approximation to the overlap and a quadratic approximation to the overall phase of the wave function.