Diffusion Monte Carlo
View article: Ultradilute Low-Dimensional Liquids
Ultradilute Low-Dimensional Liquids Open
We calculate the energy of one- and two-dimensional weakly interacting Bose-Bose mixtures analytically in the Bogoliubov approximation and by using the diffusion Monte Carlo technique. We show that in the case of attractive inter- and repu…
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Majorana Positivity and the Fermion Sign Problem of Quantum Monte Carlo Simulations Open
The sign problem is a major obstacle in quantum Monte Carlo simulations for many-body fermion systems. We examine this problem with a new perspective based on the Majorana reflection positivity and Majorana Kramers positivity. Two sufficie…
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q-AQUA: A Many-Body CCSD(T) Water Potential, Including Four-Body Interactions, Demonstrates the Quantum Nature of Water from Clusters to the Liquid Phase Open
Many model potential energy surfaces (PESs) have been reported for water; however, none are strictly from "first-principles". Here we report such a potential, based on a many-body representation at the CCSD(T) level of theory up to the fou…
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Auxiliary field diffusion Monte Carlo calculations of light and medium-mass nuclei with local chiral interactions Open
Quantum Monte Carlo methods have recently been employed to study properties of nuclei and infinite matter using local chiral effective-field-theory interactions. In this paper, we present a detailed description of the auxiliary field diffu…
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Benchmark study of the two-dimensional Hubbard model with auxiliary-field quantum Monte Carlo method Open
Ground-state properties of the Hubbard model on a two-dimensional square lattice are studied by the auxiliary-field quantum Monte Carlo method. Accurate results for energy, double occupancy, effective hopping, magnetization, and momentum d…
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Discovering Quantum Phase Transitions with Fermionic Neural Networks Open
Deep neural networks have been very successful as highly accurate wave function Ansätze for variational Monte Carlo calculations of molecular ground states. We present an extension of one such Ansatz, FermiNet, to calculations of the groun…
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Boosting the accuracy and speed of quantum Monte Carlo: Size consistency and time step Open
Diffusion Monte Carlo (DMC) simulations for fermions are becoming the\nstandard to provide high quality reference data in systems that are too large\nto be investigated via quantum chemical approaches. DMC with the fixed-node\napproximatio…
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Excitation energies from diffusion Monte Carlo using selected configuration interaction nodes Open
Quantum Monte Carlo (QMC) is a stochastic method that has been particularly successful for ground-state electronic structure calculations but mostly unexplored for the computation of excited-state energies. Here, we show that within a Jast…
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Path integral Monte Carlo simulations of warm dense aluminum Open
We perform first-principles path integral Monte Carlo (PIMC) and density functional theory molecular dynamics (DFT-MD) calculations to explore warm dense matter states of aluminum. Our equation of state (EOS) simulations cover a wide densi…
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Infinite variance in fermion quantum Monte Carlo calculations Open
For important classes of many-fermion problems, quantum Monte Carlo (QMC) methods allow exact calculations of ground-state and finite-temperature properties without the sign problem. The list spans condensed matter, nuclear physics, and hi…
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Communication: Toward an improved control of the fixed-node error in quantum Monte Carlo: The case of the water molecule Open
All-electron Fixed-node Diffusion Monte Carlo calculations for the nonrelativistic ground-state energy of the water molecule at equilibrium geometry are presented. The determinantal part of the trial wavefunction is obtained from a selecte…
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Coupled cluster benchmarks of large noncovalent complexes: The L7 dataset as well as DNA–ellipticine and buckycatcher–fullerene Open
In this work, benchmark binding energies for dispersion-bound complexes in the L7 dataset, the DNA–ellipticine intercalation complex, and the buckycatcher–C60 complex with 120 heavy atoms using a focal-point method based on the canonical f…
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<span>TurboRVB</span>: A many-body toolkit for <i>ab initio</i> electronic simulations by quantum Monte Carlo Open
TurboRVB is a computational package for ab initio Quantum Monte Carlo (QMC) simulations of both molecular and bulk electronic systems. The code implements two types of well established QMC algorithms: Variational Monte Carlo (VMC) and diff…
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Excited States with Selected Configuration Interaction-Quantum Monte Carlo: Chemically Accurate Excitation Energies and Geometries Open
We employ quantum Monte Carlo to obtain chemically accurate vertical and adiabatic excitation energies, and equilibrium excited-state structures for the small, yet challenging, formaldehyde and thioformaldehyde molecules. A key ingredient …
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One-dimensional three-boson problem with two- and three-body interactions Open
We solve the three-boson problem with contact two- and three-body interactions in one dimension and analytically calculate the ground and excited trimer-state energies. Then, by using the diffusion Monte Carlo technique we calculate the bi…
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Diffusion Monte Carlo for Accurate Dissociation Energies of 3d Transition Metal Containing Molecules Open
Transition metals and transition metal compounds are important to catalysis, photochemistry, and many superconducting systems. We study the performance of diffusion Monte Carlo (DMC) applied to transition metal containing dimers (TMCDs) us…
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Hubbard model on the honeycomb lattice: From static and dynamical mean-field theories to lattice quantum Monte Carlo simulations Open
We study the one-band Hubbard model on the honeycomb lattice using a\ncombination of quantum Monte Carlo (QMC) simulations and static as well as\ndynamical mean-field theory (DMFT). This model is known to show a quantum phase\ntransition b…
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Evidence for stable square ice from quantum Monte Carlo Open
Recent experiments on ice formed by water under nanoconfinement provide evidence for a two-dimensional (2D) “square ice” phase. However, the interpretation of the experiments has been questioned and the stability of square ice has become a…
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Perturbatively Selected Configuration-Interaction Wave Functions for Efficient Geometry Optimization in Quantum Monte Carlo Open
We investigate the performance of a class of compact and systematically improvable Jastrow-Slater wave functions for the efficient and accurate computation of structural properties, where the determinantal component is expanded with a pert…
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Deterministic Construction of Nodal Surfaces within Quantum Monte Carlo: The Case of FeS Open
In diffusion Monte Carlo (DMC) methods, the nodes (or zeroes) of the trial wave function dictate the magnitude of the fixed-node (FN) error. In standard DMC implementations, the nodes are optimized by stochastically optimizing a short mult…
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Quantum Monte Carlo calculations of energy gaps from first principles Open
We review the use of continuum quantum Monte Carlo (QMC) methods for the\ncalculation of energy gaps from first principles, and present a broad set of\nexcited-state calculations carried out with the variational and fixed-node\ndiffusion Q…
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Development of a Multicenter Density Functional Tight Binding Model for Plutonium Surface Hydriding Open
We detail the creation of a multicenter density functional tight binding (DFTB) model for hydrogen on δ-plutonium, using a framework of new Slater-Koster interaction parameters and a repulsive energy based on the Chebyshev Interaction Mode…
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Full-dimensional, <i>ab initio</i> potential energy surface for glycine with characterization of stationary points and zero-point energy calculations by means of diffusion Monte Carlo and semiclassical dynamics Open
A full-dimensional, permutationally invariant potential energy surface (PES) for the glycine amino acid is reported. A precise fit to energies and gradients calculated at the density functional theory (DFT)/B3LYP level of electronic-struct…
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Diffusion Monte Carlo study of strongly interacting two-dimensional Fermi gases Open
Ultracold atomic Fermi gases have been a popular topic of research, with attention being paid recently to two-dimensional (2D) gases. In this work, we perform T=0 ab initio diffusion Monte Carlo calculations for a strongly interacting two-…
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Surmounting the sign problem in nonrelativistic calculations: A case study with mass-imbalanced fermions Open
The calculation of the ground state and thermodynamics of mass-imbalanced Fermi systems is a challenging many-body problem. Even in one spatial dimension, analytic solutions are limited to special configurations and numerical progress with…
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Using CIPSI Nodes in Diffusion Monte Carlo Open
Several aspects of the recently proposed DMC-CIPSI approach consisting in\nusing selected Configuration Interaction (SCI) approaches such as CIPSI\n(Configuration Interaction using a Perturbative Selection done Iteratively) to\nbuild accur…
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Benchmark calculations of infinite neutron matter with realistic two- and three-nucleon potentials Open
We present the equation of state of infinite neutron matter as obtained from highly realistic Hamiltonians that include nucleon-nucleon and three-nucleon coordinate-space potentials. We benchmark three independent many-body methods: Brueck…
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Lattice Monte Carlo for quantum Hall states on a torus Open
The Monte Carlo method is very useful for studying various model states proposed for the fractional quantum Hall systems. In this paper, we introduce a lattice Monte Carlo method based on an exact lattice formalism for quantum Hall problem…
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A first-principles Quantum Monte Carlo study of two-dimensional (2D) GaSe Open
Two-dimensional (2D) post-transition metal chalcogenides (PTMCs) have attracted attention due to their suitable bandgaps and lower exciton binding energies, making them more appropriate for electronic, optical, and water-splitting devices …
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Diffusion quantum Monte Carlo and density functional calculations of the structural stability of bilayer arsenene Open
We have studied the structural stability of monolayer and bilayer arsenene (As) in the buckled (b) and washboard (w) phases with diffusion quantum Monte Carlo (DMC) and density functional theory (DFT) calculations. DMC yields cohesive ener…