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A software library is presented for the polynomial expansion method (PEM) of the density of states (DOS) developed by two of the authors (N.F. and Y. M.). The library provides all necessary functions for the use of the PEM and its truncated…

Strongly Correlated Electrons · Physics 2007-05-23 G. Alvarez , C. Sen , N. Furukawa , Y. Motome , E. Dagotto

We present a quantum Monte-Carlo algorithm for computing the perturbative expansion in power of the coupling constant $U$ of the out-of-equilibrium Green's functions of interacting Hamiltonians of fermions. The algorithm extends the one…

Strongly Correlated Electrons · Physics 2019-09-23 Corentin Bertrand , Olivier Parcollet , Antoine Maillard , Xavier Waintal

We describe an application of variational Monte Carlo to two-dimensional fermionic systems within the recently developed tensor-network string-bond state (SBS) ansatz. We use a combination of variational Monte Carlo and stochastic…

Strongly Correlated Electrons · Physics 2014-03-04 J. -P. Song , R. T. Clay

We present a simple, general purpose, quantum Monte-Carlo algorithm for out-of-equilibrium interacting nanoelectronics systems. It allows one to systematically compute the expansion of any physical observable (such as current or density) in…

Mesoscale and Nanoscale Physics · Physics 2015-07-08 Rosario E. V. Profumo , Christoph Groth , Laura Messio , Olivier Parcollet , Xavier Waintal

I discuss our recent work on Green's function Monte Carlo (GFMC) calculations of light nuclei using local nucleon-nucleon interactions derived from chiral effective field theory (EFT) up to next-to-next-to-leading order (N$^2$LO). I present…

Nuclear Theory · Physics 2016-04-20 J. E. Lynn

The Abrikosov fermion representation of the spin-1/2 degree of freedom allows for auxiliary-field quantum Monte Carlo simulations of frustrated spin systems. This approach provides a manifold of equivalent actions over which the negative…

Strongly Correlated Electrons · Physics 2025-02-11 João C. Inácio , Jeroen van den Brink , Fakher F. Assaad , Toshihiro Sato

These notes are intended as a detailed discussion on how to implement the diagrammatic Monte Carlo method for a physical system which is technically simple and where it works extremely well, namely the Fr\"ohlich polaron problem. Sampling…

Statistical Mechanics · Physics 2019-07-02 Jonas Greitemann , Lode Pollet

On the base of the diffusion Monte-Carlo method we develop the method allowing to simulate the quantum systems with complex wave function. The method is exact and there are no approximations on the simulations of the module and the phase of…

Condensed Matter · Physics 2007-05-23 B. Abdullaev , M. Musakhanov , A. Nakamura

Quantum Monte Carlo is one of the most powerful numerical tools for studying nonpeturbative properties of quantum many-body systems. However, its application to real-time problems is limited since the complex and highly-oscillating…

Quantum Physics · Physics 2021-07-16 Tomoya Hayata

In this work we present a novel quantum Monte-Carlo method for fermions, based on an exact decomposition of the Boltzmann operator $exp(-\beta H)$. It can be seen as a synthesis of several related methods. It has the advantage that it is…

Strongly Correlated Electrons · Physics 2009-10-31 S. Rombouts , K. Heyde , N. Jachowicz

We introduce a quantum Monte Carlo technique to calculate exactly at finite temperatures the Green function of a fermionic quantum impurity coupled to a bosonic field. While the algorithm is general, we focus on the single impurity Anderson…

Mesoscale and Nanoscale Physics · Physics 2009-11-11 Liliana Arrachea , Marcelo J. Rozenberg

The Green's function Monte Carlo (GFMC) method provides accurate solutions to the nuclear many-body problem and predicts properties of light nuclei starting from realistic two- and three-body interactions. Controlling the GFMC fermion-sign…

Nuclear Theory · Physics 2023-04-07 Gurtej Kanwar , Alessandro Lovato , Noemi Rocco , Michael Wagman

We present a Monte Carlo wavefunction method for semiclassically modeling spin-$\frac12$ systems in a magnetic field gradient in one dimension. Our model resolves the conflict of determining what classical force an atom should be subjected…

Quantum Physics · Physics 2015-02-25 C. J. Billington , C. J. Watkins , R. P. Anderson , L. D. Turner

Quantum Monte Carlo simulations of fermions are hampered by the notorious sign problem whose most striking manifestation is an exponential growth of sampling errors with the number of particles. With the sign problem known to be an NP-hard…

Statistical Mechanics · Physics 2016-08-23 Peter Broecker , Simon Trebst

The accuracy of Green Function Monte Carlo (GFMC) simulations can be greatly improved by a clever choice of the approximate ground state wave function that controls configuration sampling. This trial wave function typically depends on many…

High Energy Physics - Lattice · Physics 2007-05-23 Matteo Beccaria , Massimo Campostrini , Alessandra Feo

A new method for the stabilization of the sign problem in the Green Function Monte Carlo technique is proposed. The method is devised for real lattice Hamiltonians and is based on an iterative ''stochastic reconfiguration'' scheme which…

Condensed Matter · Physics 2009-10-31 S. Sorella

We demonstrate, by considering the triangular lattice spin-1/2 Heisenberg model, that Monte Carlo sampling of skeleton Feynman diagrams within the fermionization framework offers a universal first-principles tool for strongly correlated…

Strongly Correlated Electrons · Physics 2013-04-09 S. A. Kulagin , N. Prokof'ev , O. A. Starykh , B. Svistunov , C. N. Varney

We introduce a method that combines the power of both the lattice Green function Monte Carlo (LGFMC) with the auxiliary field techniques (AFQMC), and allows us to compute exact ground state properties of the Hubbard model for U<~ 4t on…

Strongly Correlated Electrons · Physics 2015-06-03 Sandro Sorella

Entanglement measures such as the entanglement entropy have become an indispensable tool to identify the fundamental character of ground states of interacting quantum many-body systems. For systems of interacting spin or bosonic degrees of…

Strongly Correlated Electrons · Physics 2014-08-27 Peter Broecker , Simon Trebst

Monte Carlo simulations are performed in classical phase space for a one-dimensional quantum harmonic crystal. Symmetrization effects for spinless bosons and fermions are quantified. The algorithm is tested for a range of parameters against…

Quantum Physics · Physics 2019-04-25 Phil Attard