Path integral molecular dynamics approximations of quantum canonical observables
| العنوان: | Path integral molecular dynamics approximations of quantum canonical observables |
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| المؤلفون: | Huang, Xin, Plecháč, Petr, Sandberg, Mattias, Szepessy, Anders, 1960 |
| المصدر: | Journal of Computational Physics. 523 |
| مصطلحات موضوعية: | Ab initio molecular dynamics, Canonical ensemble, Fermion sign problem, Gibbs distribution, Path integral |
| الوصف: | Mean-field molecular dynamics based on path integrals is used to approximate canonical quantum observables for particle systems consisting of nuclei and electrons. A computational bottleneck is the Monte Carlo sampling from the Gibbs density of the electron operator, which due to the fermion sign problem has a computational complexity that scales exponentially with the number of electrons. In this work, we construct an algorithm that approximates the mean-field Hamiltonian by path integrals for fermions. The algorithm is based on the determinant of a matrix with components built on Brownian bridges connecting permuted electron coordinates. The computational work for n electrons is O(n3), which reduces the computational complexity associated with the fermion sign problem. We analyze a bias resulting from this approximation and provide a rough computational error indicator. It remains to rigorously explain the surprisingly high accuracy for high temperatures. The method becomes infeasible at low temperatures due to a large sample variance. |
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| URL الوصول: | https://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-357912 https://doi.org/10.1016/j.jcp.2024.113625 |
| قاعدة البيانات: | SwePub |
| تدمد: | 00219991 10902716 |
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| DOI: | 10.1016/j.jcp.2024.113625 |