Feynman-Kleinert Linearized Path Integral (FK-LPI) Algorithms for Quantum Molecular Dynamics, with Application to Water and He(4)

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• 作者：Jens Aage Poulsen ; Gunnar Nyman ; Peter J. Rossky
• 刊名：Journal of Chemical Theory and Computation
• 出版年：2006
• 出版时间：November 2006
• 年：2006
• 卷：2
• 期：6
• 页码：1482 - 1491
• 全文大小：157K
• 年卷期：v.2,no.6(November 2006)
• ISSN：1549-9626

文摘

The Feynman-Kleinert Linearized Path Integral (FK-LPI) representation of quantumcorrelation functions is extended in applications and algorithms. Diffusion including quantumeffects for a flexible simple point charge model of liquid water is explored, including new testsof internal consistency. An ab initio quantum correction factor (QCF) is also obtained to correctthe far-infrared spectrum of water. After correction, a spectrum based on a classical simulationis in good agreement with the experiment. The FK-LPI QCF is shown to be superior to theso-called harmonic QCF. New computational algorithms are introduced so that the quantumBoltzmann Wigner phase-space density, the central object in the implementation, can be obtainedfor arbitrary potentials. One scheme requires only that the standard classical force routine bereplaced when turning from one molecular problem to another. The new algorithms are appliedto the calculation of the Van Hove spectrum of liquid He(4) at 27 K. The spectrum moments arein very good agreement with the experiment. These observations indicate that the FK-LPIapproach can be broadly effective for molecular problems involving the dynamics of light nuclei.