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We introduce regular series expansion for weakly- and moderately-correlated fermionic systems, based on Fluctuating Local Field approach. The method relies on the explicit account of leading fluctuating mode(s) and is therefore suitable for…

Strongly Correlated Electrons · Physics 2024-12-25 Ya. S. Lyakhova , S. D. Semenov , A. I. Lichtenstein , A. N. Rubtsov

Quantum Monte Carlo is an efficient technique for finding the ground-state energy and related properties of small molecules. A major challenge remains in accurate determination of a molecule's geometry, i.e. the optimal location of its…

Computational Physics · Physics 2017-04-12 Jan Vrbik

Within the framework of quenched lattice QCD and using O(a) improved Wilson fermions and non-perturbative renormalisation, a high statistics computation of low moments of the unpolarised nucleon structure functions is given. Particular…

High Energy Physics - Phenomenology · Physics 2008-11-26 M. Göckeler , R. Horsley , D. Pleiter , P. E. L. Rakow , G. Schierholz

This Dissertation presents results of a thorough study of ultracold bosonic and fermionic gases in three-dimensional and quasi-one-dimensional systems. Although the analyses are carried out within various theoretical frameworks…

Quantum Gases · Physics 2014-12-16 G. E. Astrakharchik

We present numerical methods to solve the Generalized Hartree-Fock theory for fermionic systems in lattices, both in thermal equilibrium and out of equilibrium. Specifically, we show how to determine the covariance matrix corresponding to…

Quantum Physics · Physics 2013-04-10 Christina V. Kraus , J. Ignacio Cirac

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

This project investigates the applicability of quasi-Monte Carlo methods to Euclidean lattice systems in order to improve the asymptotic error scaling of observables for such theories. The error of an observable calculated by averaging over…

High Energy Physics - Lattice · Physics 2013-11-20 Andreas Ammon , Tobias Hartung , Karl Jansen , Hernan Leovey , Andreas Griewank , Micheal Müller-Preussker

Single particle basis functions for composite fermions are obtained from which many-composite fermion states confined to the lowest electronic Landau level can be constructed in the standard manner, i.e., by building Slater determinants.…

Mesoscale and Nanoscale Physics · Physics 2009-10-30 J. K. Jain , R. K. Kamilla

The entanglement entropy probing novel phases and phase transitions numerically via quantum Monte Carlo has made great achievements in large-scale interacting spin/boson systems. In contrast, the numerical exploration in interacting fermion…

Statistical Mechanics · Physics 2025-05-15 Weilun Jiang , Gaopei Pan , Zhe Wang , Bin-Bin Mao , Heng Shen , Zheng Yan

In this work we develop tools that enable the study of non-adiabatic effects with variational and diffusion Monte Carlo methods. We introduce a highly accurate wave function ansatz for electron-ion systems that can involve a combination of…

Chemical Physics · Physics 2014-10-29 Norm M. Tubman , Ilkka Kylänpää , Sharon Hammes-Schiffer , David M. Ceperley

In this contribution, a first look at simulations using maximally twisted mass Wilson fermions at the physical point is presented. A lattice action including clover and twisted mass terms is presented and the Monte Carlo histories of one…

We study harmonically trapped, unpolarized fermion systems with attractive interactions in two spatial dimensions with spin degeneracies Nf = 2 and 4 and N/Nf = 1, 3, 5, and 7 particles per flavor. We carry out our calculations using our…

Quantum Gases · Physics 2016-03-09 Z. -H. Luo , C. E. Berger , J. E. Drut

The recently developed auxiliary field diffusion Monte Carlo method is applied to compute the equation of state and the compressibility of neutron matter. By combining diffusion Monte Carlo for the spatial degrees of freedom and auxiliary…

Nuclear Theory · Physics 2009-11-10 A. Sarsa , S. Fantoni , K. E. Schmidt , F. Pederiva

We give a detailed description of the so-called Polynomial Hybrid Monte Carlo (PHMC) algorithm. The effects of the correction factor, which is introduced to render the algorithm exact, are discussed, stressing their relevance for the…

High Energy Physics - Lattice · Physics 2009-10-31 R. Frezzotti , K. Jansen

We discuss differences and similarities between variational Monte Carlo approaches that use conventional and artificial neural network parameterizations of the ground-state wave function for systems of fermions. We focus on a relatively…

Mesoscale and Nanoscale Physics · Physics 2025-01-13 Even M. Nordhagen , Jane M. Kim , Bryce Fore , Alessandro Lovato , Morten Hjorth-Jensen

We study the ground state of the two-dimensional (2D) disordered Hubbard model by means of the projector quantum Monte Carlo (PQMC) method. This approach allows us to investigate the ground state properties of this model for lattice sizes…

Disordered Systems and Neural Networks · Physics 2009-10-31 Gaetan Caldara , Bhargavi Srinivasan , Dima Shepelyansky

The diffusion quantum Monte Carlo method is extended to solve the old theoretical physics problem of many-electron atoms and ions in intense magnetic fields. The feature of our approach is the use of adiabatic approximation wave functions…

Quantum Physics · Physics 2009-11-13 S. Bucheler , D. Engel , J. Main , G. Wunner

We develop an implementation for a recently proposed Noisy Monte Carlo approach to the simulation of lattice QCD with dynamical fermions by incorporating the full fermion determinant directly. Our algorithm uses a quenched gauge field…

High Energy Physics - Lattice · Physics 2009-11-07 B. Joo , I. Horvath , K. F. Liu

We tutorially review the determinantal Quantum Monte Carlo method for fermionic systems, using the Hubbard model as a case study. Starting with the basic ingredients of Monte Carlo simulations for classical systems, we introduce aspects…

Strongly Correlated Electrons · Physics 2007-05-23 Raimundo R. dos Santos

A recently developed lattice method for large numbers of strongly interacting nonrelativistic fermions exhibits a heavy tail in the distributions of correlators for large Euclidean time {\tau} and large number of fermions N, which only…

High Energy Physics - Lattice · Physics 2015-03-19 Jong-Wan Lee , Michael G. Endres , David B. Kaplan , Amy N. Nicholson