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Auxiliary Field Quantum Monte Carlo (AFQMC) has emerged as a powerful framework for treating strongly correlated electronic systems, offering a favorable balance between computational cost and accuracy. In this paper, we present a novel…

Chemical Physics · Physics 2026-04-03 Maxine Luo , Victor Chen , Yu Wang , Christian B. Mendl

The ground state electronic energy of benzene is the focus of a recent blind test by Eriksen and co-workers [arXiv:2008.02678]. In this note, we report the phaseless auxiliary-field quantum Monte Carlo (ph-AFQMC) results on the identical…

Chemical Physics · Physics 2020-09-23 Joonho Lee , Fionn D. Malone , David R. Reichman

The auxiliary-field quantum Monte Carlo (AFQMC) method is a general numerical method for correlated many-electron systems, which is being increasingly applied in lattice models, atoms, molecules, and solids. Here we introduce the theory and…

Computational Physics · Physics 2021-02-24 Hao Shi , Shiwei Zhang

We introduce an efficient approach to implement correlated many-body trial wave functions in auxiliary-field quantum Monte Carlo (AFQMC). To control the sign/phase problem in AFQMC, a constraint is derived from an exact gauge condition but…

Strongly Correlated Electrons · Physics 2025-10-27 Zhi-Yu Xiao , Zixiang Lu , Yixiao Chen , Tao Xiang , Shiwei Zhang

We describe computational methods for the theoretical study of explicit correlations beyond the mean field in excitons confined in semiconductor quantum dots in terms of the Auxiliary-Field Monte Carlo (AFMC) method. Using AFMC, the…

Strongly Correlated Electrons · Physics 2009-09-25 D. J. Dean , M. R. Strayer , J. C. Wells

To make useful connections with experimental measurements, correlated electronic structure theories must accurately predict chemical properties in addition to energies. We present a finite-difference based algorithm to compute first-order…

Chemical Physics · Physics 2025-09-24 Leon Otis , Sri Gudivada , Marvin Friede , James Shee

In this work, we develop a size extensive Auxiliary-Field Quantum Monte Carlo (AFQMC) approach that scales as $O(N^5)$ for local energy evaluation by treating the Coupled Cluster Singles and Doubles (CCSD) trial wavefunctions…

Chemical Physics · Physics 2026-05-13 Yichi Zhang , Ankit Mahajan , Yann Damour , Sandeep Sharma

We marry tensor network states (TNS) and projector quantum Monte Carlo (PMC) to overcome the high computational scaling of TNS and the sign problem of PMC. Using TNS as trial wavefunctions provides a route to systematically improve the sign…

Strongly Correlated Electrons · Physics 2014-07-04 Sebastian Wouters , Brecht Verstichel , Dimitri Van Neck , Garnet Kin-Lic Chan

We investigate the phase diagram and the mechanism for the sign problem to appear in finite density QCD at strong coupling in a combined framework of the auxiliary field Monte-Carlo (AFMC) and the chiral angle fixing (CAF) methods. When…

High Energy Physics - Lattice · Physics 2013-11-22 Terukazu Ichihara , Takashi Z. Nakano , Akira Ohnishi

We explore different ways of incorporating accurate trial wave functions into free projection auxiliary field quantum Monte Carlo (fp-AFQMC). Trial states employed include coupled cluster singles and doubles, multi-Slater, and symmetry…

Chemical Physics · Physics 2021-04-15 Ankit Mahajan , Sandeep Sharma

The use of an approximate reference state wave function |Phi_r> in electronic many-body methods can break the spin symmetry of Born-Oppenheimer spin-independent Hamiltonians. This can result in significant errors, especially when bonds are…

Computational Physics · Physics 2008-03-19 Wirawan Purwanto , W. A. Al-Saidi , Henry Krakauer , Shiwei Zhang

The auxiliary-field quantum Monte Carlo (AFQMC) method provides a computational framework for solving the time-independent Schroedinger equation in atoms, molecules, solids, and a variety of model systems by stochastic sampling. We…

Strongly Correlated Electrons · Physics 2018-07-19 Shiwei Zhang

Spin-orbit coupling (SOC) is incorporated into the phaseless plane-wave-based auxiliary-field quantum Monte Carlo (pw-AFQMC) method. This integration is implemented using optimized multiple-projector norm-conserving pseudopotentials, which…

Materials Science · Physics 2026-02-13 Zheng Liu , Shiwei Zhang , Fengjie Ma

In this work, we test a recently developed method to enhance classical auxiliary-field quantum Monte Carlo (AFQMC) calculations with quantum computers against examples from chemistry and material science, representatives of classes of…

Quantum Monte Carlo (QMC) methods are some of the most accurate methods for simulating correlated electronic systems. We investigate the compatibility, strengths and weaknesses of two such methods, namely, diffusion Monte Carlo (DMC) and…

Computational Physics · Physics 2020-10-14 Fionn D. Malone , Anouar Benali , Miguel A. Morales , Michel Caffarel , P. R. C. Kent , Luke Shulenburger

We present efficient algorithms for using selected configuration interaction (sCI) trial wave functions in phaseless auxiliary field quantum Monte Carlo (ph-AFQMC). These advancements, geared towards optimizing computational performance for…

Chemical Physics · Physics 2022-05-18 Ankit Mahajan , Joonho Lee , Sandeep Sharma

In the study of strongly-correlated, many-electron systems, the Hubbard Kanamori (HK) model has emerged as one of the prototypes for transition metal oxide physics. The model is multi-band in nature and contains Hund's coupling terms, which…

Strongly Correlated Electrons · Physics 2019-06-26 Hongxia Hao , Brenda M. Rubenstein , Hao Shi

Quantum Monte Carlo (QMC) algorithms have long relied on Jastrow factors to incorporate dynamic correlation into trial wave functions. While Jastrow-type wave functions have been widely employed in real-space algorithms, they have seen…

Strongly Correlated Electrons · Physics 2016-12-28 Chia-Chen Chang , Brenda M. Rubenstein , Miguel A. Morales

The computational demand posed by applying multi-Slater determinant trials in phaseless auxiliary-field quantum Monte Carlo methods (MSD-AFQMC) is particularly significant for molecules exhibiting strong correlations. Here, we propose using…

Chemical Physics · Physics 2023-12-27 Hung Q. Pham , Runsheng Ouyang , Dingshun Lv

Quantum Monte Carlo (QMC) methods are powerful approaches for solving electronic structure problems. Although they often provide high-accuracy solutions, the precision of most QMC methods is ultimately limited by a trial wave function that…

Quantum Physics · Physics 2025-03-13 Nick S. Blunt , Laura Caune , Javiera Quiroz-Fernandez