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Diffusion Monte Carlo (DMC) is an exact technique to project out the ground state (GS) of a Hamiltonian. Since the GS is always bosonic, in fermionic systems the projection needs to be carried out while imposing anti-symmetric constraints,…

Computational Physics · Physics 2025-01-08 Kousuke Nakano , Sandro Sorella , Dario Alfè , Andrea Zen

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…

Development of exponentially scaling methods has seen great progress in tackling larger systems than previously thought possible. One such technique, full configuration interaction quantum Monte Carlo, is a useful algorithm that allows…

Strongly Correlated Electrons · Physics 2016-08-23 Norm M. Tubman , Joonho Lee , Tyler Y. Takeshita , Martin Head-Gordon , K. Birgitta Whaley

We formulate a quantum Monte Carlo (QMC) method for calculating the ground state of many-boson systems. The method is based on a field-theoretical approach, and is closely related to existing fermion auxiliary-field QMC methods which are…

Computational Physics · Physics 2009-11-10 Wirawan Purwanto , Shiwei Zhang

We perform quantum Monte Carlo (QMC) calculations to determine minimum energy pathways of simple chemical reactions, and compare the computed geometries and reaction barriers with those obtained with density functional theory (DFT) and…

Chemical Physics · Physics 2015-06-12 Sebastiano Saccani , Claudia Filippi , Saverio Moroni

In recent years Quantum Monte Carlo techniques provided to be a valuable tool to study strongly interacting Fermi gases at zero temperature. We have used QMC methods to investigate several properties of the two-components Fermi gas at…

Quantum Gases · Physics 2015-06-18 Stefano Gandolfi

We present the first quantum Monte Carlo (QMC) calculations with chiral effective field theory (EFT) interactions. To achieve this, we remove all sources of nonlocality, which hamper the inclusion in QMC calculations, in nuclear forces to…

Nuclear Theory · Physics 2013-07-24 A. Gezerlis , I. Tews , E. Epelbaum , S. Gandolfi , K. Hebeler , A. Nogga , A. Schwenk

Diffusion Monte Carlo (DMC) is being recognized as a higher-accuracy, albeit more computationally expensive, alternative to Density Functional Theory (DFT) for energy predictions of catalytic systems. A major computational bottleneck in the…

Materials Science · Physics 2022-10-12 Gopal R. Iyer , Brenda M. Rubenstein

Highly accurate results for the homogeneous electron gas (HEG) have only been achieved to date within a diffusion Monte Carlo (DMC) framework. Here, we introduce a newly developed stochastic technique, Full Configuration Interaction Quantum…

Quantum Gases · Physics 2012-02-22 James J. Shepherd , George Booth , Andreas Grüneis , Ali Alavi

We provide a pedagogical introduction to the two main variants of real-space quantum Monte Carlo methods for electronic-structure calculations: variational Monte Carlo (VMC) and diffusion Monte Carlo (DMC). Assuming no prior knowledge on…

Chemical Physics · Physics 2015-08-13 Julien Toulouse , Roland Assaraf , C. J. Umrigar

We report a study of the electronic dissociation energy of the water dimer using quantum Monte Carlo (QMC) techniques. We have performed variational quantum Monte Carlo (VMC) and diffusion quantum Monte Carlo (DMC) calculations of the…

Other Condensed Matter · Physics 2009-11-13 I. G. Gurtubay , R. J. Needs

In this work, we test a recently developed method to enhance classical auxiliary-field quantum Monte Carlo (AFQMC) calculations with quantum computers against examples from chemistry and material science, representatives of classes of…

We have used the variational and diffusion quantum Monte Carlo methods to calculate the energy, pair correlation function, static structure factor, and momentum density of the ground state of the two-dimensional homogeneous electron gas. We…

Mesoscale and Nanoscale Physics · Physics 2010-03-02 N. D. Drummond , R. J. Needs

We present the extension of variational Monte Carlo (VMC) to the calculation of electronic excitation energies and oscillator strengths using time-dependent linear-response theory. By exploiting the analogy existing between the linear…

Chemical Physics · Physics 2018-11-08 Bastien Mussard , Emanuele Coccia , Roland Assaraf , Matt Otten , C. J. Umrigar , Julien Toulouse

We introduce a theoretical approach to study the quantum-dissipative dynamics of electronic excitations in macromolecules, which enables to perform calculations in large systems and cover long time intervals. All the parameters of the…

Mesoscale and Nanoscale Physics · Physics 2016-07-20 S. A Beccara , F. Mascherpa , E. Schneider , P. Faccioli

According to Landau's Fermi liquid theory, the main properties of the quasiparticle excitations of an electron gas are embodied in the effective mass $m^*$, which determines the energy of a single quasiparticle, and the Landau interaction…

Strongly Correlated Electrons · Physics 2021-08-25 Sam Azadi , N. D. Drummond , W. M. C. Foulkes

We report state-of-the-art quantum Monte Carlo calculations of the singlet $n \to \pi^*$ (CO) vertical excitation energy in the acrolein molecule, extending the recent study of Bouab\c{c}a {\it et al.} [J. Chem. Phys. {\bf 130}, 114107…

Chemical Physics · Physics 2010-12-24 Julien Toulouse , Michel Caffarel , Peter Reinhardt , Philip E. Hoggan , C. J. Umrigar

We investigate the use of different variational principles in quantum Monte Carlo, namely energy and variance minimization, prompted by the interest in the robust and accurate estimate of electronic excited states. For two prototypical,…

Chemical Physics · Physics 2021-11-19 Alice Cuzzocrea , Anthony Scemama , Wim J. Briels , Saverio Moroni , Claudia Filippi

We propose an end-to-end integrated strategy to produce highly accurate quantum chemistry (QC) synthetic datasets (energies and forces) aimed at deriving Foundation Machine Learning models for molecular simulation. Starting from Density…

The perturbatively selected configuration interaction scheme (CIPSI) is particularly effective in constructing determinantal expansions for quantum Monte Carlo (QMC) simulations with Jastrow-Slater wave functions: fast and smooth…

Classical Physics · Physics 2021-03-02 Monika Dash , Saverio Moroni , Claudia Filippi , Anthony Scemama
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