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Quantum Monte Carlo (QMC) methods represent a powerful family of computational techniques for tackling complex quantum many-body problems and performing calculations of stationary state properties. QMC is among the most accurate and…

Materials Science · Physics 2025-01-08 Alfonso Annarelli , Dario Alfè , Andrea Zen

Artificial neural networks have been successfully incorporated into variational Monte Carlo method (VMC) to study quantum many-body systems. However, there have been few systematic studies of exploring quantum many-body physics using deep…

Strongly Correlated Electrons · Physics 2020-02-26 Li Yang , Zhaoqi Leng , Guangyuan Yu , Ankit Patel , Wen-Jun Hu , Han Pu

We demonstrate a scaling method for non-Markovian Monte Carlo wave-function simulations used to study open quantum systems weakly coupled to their environments. We derive a scaling equation, from which the result for the expectation values…

Quantum Physics · Physics 2009-11-10 J. Piilo , S. Maniscalco , A. Messina , F. Petruccione

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…

The toolbox for imaging molecules is well-equipped today. Some techniques visualize the geometrical structure, others the electron density or electron orbitals. Molecules are many-body systems for which the correlation between the…

We review an approach where the energy functional of Density-Functional Theory (DFT) can be determined without empiricism via a Quantum Monte Carlo (QMC) procedure. The idea consists of a nested iterative loop where the configurational…

Strongly Correlated Electrons · Physics 2017-11-22 Luigi Delle Site

Quantum Monte Carlo (QMC) algorithms have long relied on Jastrow factors to incorporate dynamic correlation into trial wave functions. While Jastrow-type wave functions have been widely employed in real-space algorithms, they have seen…

Strongly Correlated Electrons · Physics 2016-12-28 Chia-Chen Chang , Brenda M. Rubenstein , Miguel A. Morales

We report the first successful application of the {\it ab initio} quantum Monte Carlo (QMC) framework to a phonon dispersion calculation. A full phonon dispersion of diamond is successfully calculated at the variational Monte Carlo (VMC)…

Materials Science · Physics 2021-04-14 Kousuke Nakano , Tommaso Morresi , Michele Casula , Ryo Maezono , Sandro Sorella

We apply diffusion quantum Monte Carlo (DMC) to a broad set of solids, benchmarking the method by comparing bulk structural properties (equilibrium volume and bulk modulus) to experiment and DFT based theories. The test set includes…

Materials Science · Physics 2015-06-17 Luke Shulenburger , Thomas R. Mattsson

We propose here a single Pfaffian correlated variational ansatz, that dramatically improves the accuracy with respect to the single determinant one, while remaining at a similar computational cost. A much larger correlation energy is indeed…

Chemical Physics · Physics 2020-07-28 Claudio Genovese , Tomonori Shirakawa , Kousuke Nakano , Sandro Sorella

We investigate pfaffian trial wave functions with singlet and triplet pair orbitals by quantum Monte Carlo methods. We present mathematical identities and the key algebraic properties necessary for efficient evaluation of pfaffians.…

Other Condensed Matter · Physics 2013-05-29 M. Bajdich , L. Mitas , L. K. Wagner , K. E. Schmidt

We show that the standard Lanczos algorithm can be efficiently implemented statistically and self consistently improved, using the stochastic reconfigurat ion method, which has been recently introduced to stabilize the Monte Carlo sign…

Strongly Correlated Electrons · Physics 2009-02-05 S. Sorella

We propose a variational wavefunction containing parameters to tune the probabilities of all the possible onsite configurations for the periodic Anderson model. We call it the full onsite-correlation wavefunction (FOWF). This is a simple…

Strongly Correlated Electrons · Physics 2016-12-01 Katsunori Kubo , Hiroaki Onishi

Based on the canonical Lang-Firsov transformation of the Hamiltonian we develop a very efficient quantum Monte Carlo algorithm for the Holstein model with one electron. Separation of the fermionic degrees of freedom by a reweighting of the…

Strongly Correlated Electrons · Physics 2007-05-23 Martin Hohenadler , Hans Gerd Evertz , Wolfgang von der Linden

A general-purpose, self-adapting Monte Carlo (MC) algorithm implemented in the program {\tt Foam} is described. The high efficiency of the MC, that is small maximum weight or variance of the MC weight is achieved by means of dividing the…

Computational Physics · Physics 2009-11-07 S. Jadach

We present a recently developed projector quantum Monte Carlo method for calculations of electronic structure in systems with spin-orbit interactions. The method solves for many-body eigenstates in the presence of spin-orbit using the…

Chemical Physics · Physics 2017-08-09 Cody A. Melton , M. Chandler Bennett , Lubos Mitas

When solving stochastic partial differential equations (SPDEs) driven by additive spatial white noise, the efficient sampling of white noise realizations can be challenging. Here, we present a new sampling technique that can be used to…

Numerical Analysis · Mathematics 2023-01-10 Matteo Croci , Michael B. Giles , Marie E. Rognes , Patrick E. Farrell

Clusters of sizes ranging from two to five are studied by variational quantum Monte Carlo techniques. The clusters consist of Ar, Ne and hypothetical lighter (``$1 \over 2$-Ne") atoms. A general form of trial function is developed for which…

chem-ph · Physics 2009-10-22 Andrei Mushinski , M. P. Nightingale

Employing a classical density-functional description of liquid environments, we introduce a rigorous method for the diffusion quantum Monte Carlo calculation of free energies and thermodynamic averages of solvated systems that requires…

We evaluate using programmable superconducting flux qubit D-Wave quantum annealers to approximate the partition function of Ising models. We propose the use of two distinct quantum annealer sampling methods: chains of Monte Carlo-like…

Quantum Physics · Physics 2025-12-23 Thinh Le , Elijah Pelofske