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We present a first-principle numerical study of charge transport in a realistic two-dimensional tight-binding model of organic molecular semiconductors. We use the Hybrid Monte Carlo (HMC) algorithm to simulate the full quantum dynamics of…

Materials Science · Physics 2024-09-12 Johann Ostmeyer , Tahereh Nematiaram , Alessandro Troisi , Pavel Buividovich

We present a finite-temperature canonical-ensemble determinant quantum Monte Carlo algorithm that enforces an exact fermion number and enables stable simulations of correlated lattice fermions. We propose a stabilized QR update that reduces…

Strongly Correlated Electrons · Physics 2026-01-21 Tu Hong , Kun Chen , Xiao Yan Xu

Recently developed pair coupled cluster doubles (pCCD) theory successfully reproduces doubly occupied configuration interaction (DOCI) with mean field cost. However, the projective nature of pCCD makes the method non-variational and thus…

Chemical Physics · Physics 2016-08-19 Luning Zhao , Eric Neuscamman

We calculate the ground-state properties of unpolarized two-component Fermi gas by the diffusion quantum Monte Carlo (DMC) methods. Using an extrapolation to the zero effective range of the attractive two-particle interaction, we find…

Quantum Gases · Physics 2013-05-29 Xin Li , Jindrich Kolorenc , Lubos Mitas

We present three modifications to our recently introduced fast randomized iteration method for full configuration interaction (FCI-FRI) and investigate their effects on the method's performance for Ne, H$_2$O, and N$_2$. The initiator…

Computational Physics · Physics 2023-10-03 Samuel M. Greene , Robert J. Webber , Jonathan Weare , Timothy C. Berkelbach

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 describe an algorithm to reduce the cost of auxiliary-field quantum Monte Carlo (AFQMC) calculations for the electronic structure problem. The technique uses a nested low-rank factorization of the electron repulsion integral (ERI). While…

Computational Physics · Physics 2019-07-02 Mario Motta , James Shee , Shiwei Zhang , Garnet Kin-Lic Chan

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

We apply a diagrammatic Monte Carlo method to the problem of an impurity interacting resonantly with a homogeneous Fermi bath for a quasi-two-dimensional setup. Notwithstanding the series divergence, we can show numerically that the three…

Quantum Gases · Physics 2014-09-18 Peter Kroiss , Lode Pollet

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

An adaptation of the full configuration interaction quantum Monte Carlo (FCIQMC) method is presented, for correlated electron problems containing heavy elements and the presence of significant relativistic effects. The modified algorithm…

Chemical Physics · Physics 2020-10-26 Robert J. Anderson , George H. Booth

We introduce QC-CBT-AFQMC, a hybrid algorithm that incorporates computational basis tomography (CBT) into the quantum-classical auxiliary-field quantum Monte Carlo (QC-AFQMC) method proposed by Huggins et al. [Nature 603, 416-420 (2022)],…

Quantum Physics · Physics 2025-12-30 Viktor Khinevich , Wataru Mizukami

We study several aspects of the recently introduced fixed-phase spin-orbit diffusion Monte Carlo (FPSODMC) method, in particular, its relation to the fixed-node method and its potential use as a general approach for electronic structure…

Computational Physics · Physics 2017-10-18 Cody A. Melton , Lubos Mitas

Wave-function Monte Carlo methods are an important tool for simulating quantum systems, but the standard method cannot be used to simulate decoherence in continuously measured systems. Here we present a new Monte Carlo method for such…

Quantum Physics · Physics 2013-05-29 Kurt Jacobs

The influence of strong electron-electron interactions and Wigner-molecule (WM) formation on the spectra of $2e$ singlet-triplet double-dot Si qubits is presented based on a full configuration interaction (FCI) approach that incorporates…

Mesoscale and Nanoscale Physics · Physics 2022-11-28 Constantine Yannouleas , Uzi Landman

We present an ab-initio dynamical configuration interaction (DCI) study of free- and Mg-porphyrin. DCI is a recently developed active space theory based on the L\"owdin downfolding technique. In the active space, static correlation is…

Materials Science · Physics 2020-06-18 Marc Dvorak , Patrick Rinke

We study a resonant Bose-Fermi mixture at zero temperature by using the fixed-node diffusion Monte Carlo method. We explore the system from weak to strong boson-fermion interaction, for different concentrations of the bosons relative to the…

Quantum Gases · Physics 2013-03-19 G. Bertaina , E. Fratini , S. Giorgini , P. Pieri

The Dynamic Monte Carlo (DMC) method is an established molecular simulation technique for the analysis of the dynamics in colloidal suspensions. An excellent alternative to Brownian Dynamics or Molecular Dynamics simulation, DMC is…

Soft Condensed Matter · Physics 2020-07-15 Fabián A. García Daza , Alejandro Cuetos , Alessandro Patti

Simulating entangled atoms is a prerequisite to modeling quantum materials and remains an outstanding challenge for theory. I introduce a correlated wavefunction approach capable of simulating large entangled systems, and demonstrate its…

Chemical Physics · Physics 2026-01-05 Benjamin G. Janesko

The recently developed density matrix quantum Monte Carlo (DMQMC) algorithm stochastically samples the N -body thermal density matrix and hence provides access to exact properties of many-particle quantum systems at arbitrary temperatures.…

Strongly Correlated Electrons · Physics 2015-10-15 Fionn D. Malone , N. S. Blunt , James J. Shepherd , D. K. K. Lee , J. S. Spencer , W. M. C. Foulkes