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We introduce a novel many body method which combines two powerful many body techniques, viz., quantum Monte Carlo and coupled cluster theory. Coupled cluster wave functions are introduced as importance functions in a Monte Carlo method…

Nuclear Theory · Physics 2013-12-04 Alessandro Roggero , Abhishek Mukherjee , Francesco Pederiva

We present an accurate numerical study of the equation of state of nuclear matter based on realistic nucleon--nucleon interactions by means of Auxiliary Field Diffusion Monte Carlo (AFDMC) calculations. The AFDMC method samples the spin and…

Nuclear Theory · Physics 2008-11-26 Stefano Gandolfi , Francesco Pederiva , Stefano Fantoni , Kevin E. Schmidt

The accuracy and efficiency of ab-initio quantum Monte Carlo (QMC) algorithms benefits greatly from compact variational trial wave functions that accurately reproduce ground state properties of a system. We investigate the possibility of…

Materials Science · Physics 2019-01-30 Shivesh Pathak , Lucas K. Wagner

We perform \emph{ab initio} quantum Monte Carlo (QMC) simulations of the warm dense uniform electron gas in the thermodynamic limit. By combining QMC data with linear response theory we are able to remove finite-size errors from the…

The convergence of full configuration interaction quantum Monte Carlo (FCIQMC) is accelerated using a quasi-Newton propagation (QN) which can also be applied to coupled cluster Monte Carlo (CCMC). The computational scaling of this optimised…

Chemical Physics · Physics 2020-06-11 Verena A. Neufeld , Alex J. W. Thom

The pressure-induced structural phase transition from diamond to beta-tin in silicon is an excellent test for theoretical total energy methods. The transition pressure provides a sensitive measure of small relative energy changes between…

Materials Science · Physics 2009-12-24 Wirawan Purwanto , Henry Krakauer , Shiwei Zhang

We study cluster perturbation theory [Phys. Rev. Lett. \textbf{84}, 522 (2000)] when auxiliary field quantum Monte Carlo method is used for solving the cluster hamiltonian. As a case study, we calculate the spectral functions of the Hubbard…

Strongly Correlated Electrons · Physics 2007-05-23 Fei Lin , Erik S. Sorensen , Catherine Kallin , A. John Berlinsky

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

We propose an algorithm for accurate, systematic and scalable computation of interatomic forces within the auxiliary-field Quantum Monte Carlo (AFQMC) method. The algorithm relies on the Hellman-Fenyman theorem, and incorporates Pulay…

Computational Physics · Physics 2018-05-30 Mario Motta , Shiwei Zhang

Quantum Monte Carlo (QMC) is an advanced simulation methodology for studies of manybody quantum systems. In this review, we focus on the electronic structure QMC, i.e., methods relevant for systems described by the electron-ion…

Other Condensed Matter · Physics 2010-08-16 Michal Bajdich , Lubos Mitas

Quantum Monte Carlo (QMC) methods can very accurately compute ground state properties of quantum systems. We applied these methods to a system of boson hard spheres to get exact, infinite system size results for the ground state at several…

Computational Physics · Physics 2016-09-08 Mark Dewing

We introduce an efficient and numerically stable technique to make use of a BCS trial wave function in the computation of correlation functions of strongly correlated quantum fermion systems. The technique is applicable to any projection…

Strongly Correlated Electrons · Physics 2019-08-28 Ettore Vitali , Peter Rosenberg , Shiwei Zhang

We report modifications of the ph-AFQMC algorithm that allow the use of large time steps and reliable time step extrapolation. Our modified algorithm eliminates size-consistency errors present in the standard algorithm when large time steps…

Chemical Physics · Physics 2024-03-06 Zoran Sukurma , Martin Schlipf , Moritz Humer , Amir Taheridehkordi , Georg Kresse

Quantum Monte Carlo (QMC) is a family of powerful tools for addressing quantum many-body problems. However, its applications are often plagued by the fermionic sign problem. A promising strategy is to simulate an interaction without sign…

Nuclear Theory · Physics 2025-05-01 Jun Liu , Teng Wang , Bing-Nan Lu

We incorporate explicit, non-perturbative treatment of spin-orbit coupling into ab initio auxiliary-field quantum Monte Carlo (AFQMC) calculations. The approach allows a general computational framework for molecular and bulk systems in…

Strongly Correlated Electrons · Physics 2023-02-16 Brandon Eskridge , Henry Krakauer , Hao Shi , Shiwei Zhang

We study the effects of disorder on long-range antiferromagnetic correlations in the half-filled, two dimensional, repulsive Hubbard model at T=0. A mean field approach is first employed to gain a qualitative picture of the physics and to…

Strongly Correlated Electrons · Physics 2009-11-07 M. Enjalran , F. Hebert , G. G. Batrouni , R. T. Scalettar , Shiwei Zhang

While Diffusion Monte Carlo (DMC) is in principle an exact stochastic method for \textit{ab initio} electronic structure calculations, in practice the fermionic sign problem necessitates the use of the fixed-node approximation and trial…

Many-electron problems pose some of the greatest challenges in computational science, with important applications across many fields of modern science. Fermionic quantum Monte Carlo (QMC) methods are among the most powerful approaches to…

Variational quantum Monte Carlo (QMC) is an ab-initio method for solving the electronic Schr\"odinger equation that is exact in principle, but limited by the flexibility of the available ansatzes in practice. The recently introduced deep…

Computational Physics · Physics 2021-03-26 Zeno Schätzle , Jan Hermann , Frank Noé
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