A new class of ensemble conserving algorithms for approximate quantum dynamics: Theoretical formulation and model problems.
J Chem Phys
; 142(24): 244112, 2015 Jun 28.
Article
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| MEDLINE
| ID: mdl-26133415
ABSTRACT
We develop two classes of quasi-classical dynamics that are shown to conserve the initial quantum ensemble when used in combination with the Feynman-Kleinert approximation of the density operator. These dynamics are used to improve the Feynman-Kleinert implementation of the classical Wigner approximation for the evaluation of quantum time correlation functions known as Feynman-Kleinert linearized path-integral. As shown, both classes of dynamics are able to recover the exact classical and high temperature limits of the quantum time correlation function, while a subset is able to recover the exact harmonic limit. A comparison of the approximate quantum time correlation functions obtained from both classes of dynamics is made with the exact results for the challenging model problems of the quartic and double-well potentials. It is found that these dynamics provide a great improvement over the classical Wigner approximation, in which purely classical dynamics are used. In a special case, our first method becomes identical to centroid molecular dynamics.
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01-internacional
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MEDLINE
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En
Revista:
J Chem Phys
Año:
2015
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Article
País de afiliación:
Estados Unidos