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Main Authors: He, Ran-Chen, Zeng, Jia-Xi, Yang, Shu, Wang, Cong, Ye, Qi-Jun, Li, Xin-Zheng
Format: Preprint
Published: 2025
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Online Access:https://arxiv.org/abs/2507.22779
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author He, Ran-Chen
Zeng, Jia-Xi
Yang, Shu
Wang, Cong
Ye, Qi-Jun
Li, Xin-Zheng
author_facet He, Ran-Chen
Zeng, Jia-Xi
Yang, Shu
Wang, Cong
Ye, Qi-Jun
Li, Xin-Zheng
contents To simulate indistinguishable particles, recent studies of path-integral molecular dynamics formulated their partition function $Z$ as a recurrence relation involving a variable $ξ$, with $ξ=1$(-1) for bosons (fermions). Inspired by Lee-Yang phase transition theory, we extend $ξ$ into the complex plane and reformulate $Z$ as a polynomial in $ξ$. By analyzing the distribution of the partition function zeros, we gain insights into the analytical properties of indistinguishable particles, particularly regarding the fermion sign problem (FSP). We found that at 0~K, the partition function zeros for $N$-particles are located at $ξ=-1$, $-1/2$, $-1/3$, $\cdots$, $-1/(N-1)$. This distribution disrupts the analytic continuation of thermodynamic quantities, expressed as functions of $ξ$ and typically performed along $ξ=1\to-1$, whenever the paths intersect these zeros. Moreover, we highlight the zero at $ξ= -1$, which induces an extra term in the free energy of the fermionic systems compared to ones at other $ξ=e^{iθ}$ values. If a path connects this zero to a bosonic system with identical potential energies, it brings a transition resembling a phase transition. These findings provide a fresh perspective on the successes and challenges of emerging FSP studies based on analytic continuation techniques.
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institution arXiv
publishDate 2025
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spellingShingle Revisiting the Fermion Sign Problem from the Structure of Lee-Yang Zeros. I. The Form of Partition Function for Indistinguishable Particles and Its Zeros at 0~K
He, Ran-Chen
Zeng, Jia-Xi
Yang, Shu
Wang, Cong
Ye, Qi-Jun
Li, Xin-Zheng
Statistical Mechanics
To simulate indistinguishable particles, recent studies of path-integral molecular dynamics formulated their partition function $Z$ as a recurrence relation involving a variable $ξ$, with $ξ=1$(-1) for bosons (fermions). Inspired by Lee-Yang phase transition theory, we extend $ξ$ into the complex plane and reformulate $Z$ as a polynomial in $ξ$. By analyzing the distribution of the partition function zeros, we gain insights into the analytical properties of indistinguishable particles, particularly regarding the fermion sign problem (FSP). We found that at 0~K, the partition function zeros for $N$-particles are located at $ξ=-1$, $-1/2$, $-1/3$, $\cdots$, $-1/(N-1)$. This distribution disrupts the analytic continuation of thermodynamic quantities, expressed as functions of $ξ$ and typically performed along $ξ=1\to-1$, whenever the paths intersect these zeros. Moreover, we highlight the zero at $ξ= -1$, which induces an extra term in the free energy of the fermionic systems compared to ones at other $ξ=e^{iθ}$ values. If a path connects this zero to a bosonic system with identical potential energies, it brings a transition resembling a phase transition. These findings provide a fresh perspective on the successes and challenges of emerging FSP studies based on analytic continuation techniques.
title Revisiting the Fermion Sign Problem from the Structure of Lee-Yang Zeros. I. The Form of Partition Function for Indistinguishable Particles and Its Zeros at 0~K
topic Statistical Mechanics
url https://arxiv.org/abs/2507.22779