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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 present a method to compute the many-body real-time Green's function using an adaptive variational quantum dynamics simulation approach. The real-time Green's function involves the time evolution of a quantum state with one additional…

Quantum Physics · Physics 2023-02-08 Niladri Gomes , David B. Williams-Young , Wibe A. de Jong

A Monte Carlo algorithm for computing quantum mechanical expectation values of coordinate operators in many body problems is presented. The algorithm, that relies on the forward walking method, fits naturally in a Green's Function Monte…

Condensed Matter · Physics 2009-10-28 J. Casulleras , J. Boronat

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

Quantum Monte Carlo (QMC) methods have proven to be highly accurate for computing excited states, but the choice of optimization strategies for multiple states remains an active topic of investigation. In this work, we revisit the…

Computational Physics · Physics 2025-04-15 Stuart Shepard , Anthony Scemama , Saverio Moroni , Claudia Filippi

We propose a quantum Monte Carlo approach to solve the ground state many-body Schrodinger equation for the electronic ground state. The method combines optimization from variational Monte Carlo and propagation from auxiliary field quantum…

Computational Physics · Physics 2023-04-21 Yixiao Chen , Linfeng Zhang , Weinan E , Roberto Car

We present a variational Monte Carlo algorithm for estimating the lowest excited states of a quantum system which is a natural generalization of the estimation of ground states. The method has no free parameters and requires no explicit…

Computational Physics · Physics 2024-09-04 David Pfau , Simon Axelrod , Halvard Sutterud , Ingrid von Glehn , James S. Spencer

Variational Monte Carlo methods have recently been applied to the calculation of excited states; however, it is still an open question what objective function is most effective. A promising approach is to optimize excited states using a…

Computational Physics · Physics 2023-12-04 William A. Wheeler , Kevin G. Kleiner , Lucas K. Wagner

We used methods of Bayesian statistical inference and the principle of maximum entropy to analytically continue imaginary-time Green's function generated in quantum Monte Carlo simulations to obtain the real-time Green's functions. For test…

Condensed Matter · Physics 2009-10-28 J. Bonca , J. E. Gubernatis

We describe in detail a simple and efficient Green Function Monte Carlo technique for computing both the ground state energy and the ground state properties by the ``forward walking'' scheme. The simplicity of our reconfiguration process,…

Condensed Matter · Physics 2007-05-23 M. Calandra , S. Sorella

The self-energy method for quantum impurity models expresses the correlation part of the self-energy in terms of the ratio of two Green's functions and allows for a more accurate calculation of equilibrium spectral functions than is…

Strongly Correlated Electrons · Physics 2021-11-24 H. T. M. Nghiem , T. A. Costi

We present the first Green's function Monte Carlo calculations of light nuclei with nuclear interactions derived from chiral effective field theory up to next-to-next-to-leading order. Up to this order, the interactions can be constructed…

Nuclear Theory · Physics 2014-11-11 J. E. Lynn , J. Carlson , E. Epelbaum , S. Gandolfi , A. Gezerlis , A. Schwenk

An acceleration of continuous time quantum Monte Carlo (CTQMC) methods is a potentially interesting branch of work as they are matchless as impurity solvers of a density functional theory in combination with a dynamical mean field theory…

Strongly Correlated Electrons · Physics 2019-08-07 Taegeun Song , Hunpyo Lee

The single particle Green's function provides valuable information on the momentum and energy-resolved spectral properties for a strongly correlated system. In large-scale numerical calculations using quantum Monte Carlo (QMC), dynamical…

Strongly Correlated Electrons · Physics 2024-10-01 Maksymilian Kliczkowski , Lauren Keyes , Sayantan Roy , Thereza Paiva , Mohit Randeria , Nandini Trivedi , Maciej M. Maska

High-quality random samples of quantum states are needed for a variety of tasks in quantum information and quantum computation. Searching the high-dimensional quantum state space for a global maximum of an objective function with many local…

Quantum Physics · Physics 2015-04-28 Yi-Lin Seah , Jiangwei Shang , Hui Khoon Ng , David John Nott , Berthold-Georg Englert

The phaseless Auxiliary Field Quantum Monte Carlo method provides a well established approximation scheme for accurate calculations of ground state energies of many-fermions systems. Here we apply the method to the calculation of imaginary…

Strongly Correlated Electrons · Physics 2015-06-17 M. Motta , D. E. Galli , S. Moroni , E. Vitali

We present a worm sampling method for calculating one- and two-particle Green's functions using continuous-time quantum Monte Carlo simulations in the hybridization expansion (CT-HYB). Instead of measuring Green's functions by removing…

Strongly Correlated Electrons · Physics 2015-10-07 Patrik Gunacker , Markus Wallerberger , Emanuel Gull , Andreas Hausoel , Giorgio Sangiovanni , Karsten Held

The Green's function has been an indispensable tool to study many-body systems that remain one of the biggest challenges in modern quantum physics for decades. The complicated calculation of Green's function impedes the research of…

Quantum Physics · Physics 2022-05-04 Jie Zhu , Yuya O. Nakagawa , Chuan-Feng Li , Guang-Can Guo , Yong-Sheng Zhang

We calculate eigenvalues of one-dimensional quantum-systems by the exact numerical solution of the Lippmann-Schwinger equation, analogous to the scattering problem. To illustrate our method, we treat elementary problems: the harmonic and…

Quantum Physics · Physics 2019-12-04 Alexander Jurisch

The calculation of imaginary time displaced correlation functions with the auxiliary field projector quantum Monte-Carlo algorithm provides valuable insight (such as spin and charge gaps) in the model under consideration. One of the authors…

Strongly Correlated Electrons · Physics 2009-10-31 M. Feldbacher , F. F. Assaad