论文标题

有限温度辅助场量子蒙特卡洛在规范合奏中

Finite Temperature Auxiliary Field Quantum Monte Carlo in the Canonical Ensemble

论文作者

Shen, Tong, Liu, Yuan, Yu, Yang, Rubenstein, Brenda

论文摘要

有限的温度辅助田间量子蒙特卡洛方法,包括决定符量子蒙特卡洛(DQMC)和辅助场量子量蒙特卡洛(AFQMC),历史上在研究中具有多种多种晶状体模型和材料的有限温度相图的研究中具有枢轴作用。但是,尽管它们的实用性,但这些技术通常是在大规范合奏中配制的,这使得它们很难应用于超流体等冷凝物,并且很难根据规范合奏中配制的替代方法进行基准测试。在大规范合奏中的工作还伴随着与必须确定产生所需填充物的化学势相关的开销。鉴于这种背景,在这项工作中,我们提出了一种在规范合奏中进行AFQMC模拟的新递归方法,该方法不需要化学势知识。为了得出这种方法,我们利用了一个方便的事实,即AFQMC通过将多体繁殖物分解为积分的一体性问题来解决多体问题,而这些问题可以应用于非相互作用理论。我们基准在说明性玻色和费米哈伯德模型上基准了我们的技术的准确性,并证明它可以比大规范的AFQMC模拟更快地收敛到基础状态。我们认为,我们对HS转换操作员的新颖使用最初是为非交互系统得出的,这将激发各种其他方法的开发,并预计我们的技术将对在规范组合中提出的其他多体方法进行直接的性能比较。

Finite temperature auxiliary field-based Quantum Monte Carlo methods, including Determinant Quantum Monte Carlo (DQMC) and Auxiliary Field Quantum Monte Carlo (AFQMC), have historically assumed pivotal roles in the investigation of the finite temperature phase diagrams of a wide variety of multidimensional lattice models and materials. Despite their utility, however, these techniques are typically formulated in the grand canonical ensemble, which makes them difficult to apply to condensates like superfluids and difficult to benchmark against alternative methods that are formulated in the canonical ensemble. Working in the grand canonical ensemble is furthermore accompanied by the increased overhead associated with having to determine the chemical potentials that produce desired fillings. Given this backdrop, in this work, we present a new recursive approach for performing AFQMC simulations in the canonical ensemble that does not require knowledge of chemical potentials. To derive this approach, we exploit the convenient fact that AFQMC solves the many-body problem by decoupling many-body propagators into integrals over one-body problems to which non-interacting theories can be applied. We benchmark the accuracy of our technique on illustrative Bose and Fermi Hubbard models and demonstrate that it can converge more quickly to the ground state than grand canonical AFQMC simulations. We believe that our novel use of HS-transformed operators to implement algorithms originally derived for non-interacting systems will motivate the development of a variety of other methods and anticipate that our technique will enable direct performance comparisons against other many-body approaches formulated in the canonical ensemble.

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