Computing accurate forces in quantum Monte Carlo using Pulay’s corrections and energy minimization
Computing accurate forces in quantum Monte Carlo using Pulay’s corrections and energy minimization
复制标题
使用 Pulay 校正和能量最小化计算量子蒙特卡罗中的精确力
DOI：
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发表时间：
2003
期刊：
影响因子：
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通讯作者：
A. Rappe
中科院分区：
文献类型：
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作者：
M. Casalegno;M. Mella;A. Rappe
In order to overcome the difficulty of optimizing molecular geometry using quantum Monte Carlo methods, we introduce various approximations to the exact force expectation value. We follow Pulay’s suggestion [Mol. Phys. 17, 153 (1969)] to correct the Hellmann–Feynman estimator by introducing the contributions due to the changes in the wave function with respect to the nuclear positions. When used in conjunction with energy-optimized explicitly correlated trial wave functions for H2 and LiH, these approximations appear to yield accurate forces using both the variational and diffusion Monte Carlo methods. Also, the accuracy of the second-order estimate of the Hellmann–Feynman force estimator was investigated employing our energy-optimized trial wave functions, and an erratic behavior was uncovered for some of the studied bond lengths. The additional computational cost required to compute the corrections to the Hellmann–Feynman estimator was found to be only a small fraction of the cost for a simple mean ener...
