QMeCha: quantum Monte Carlo package for fermions in embedding environments

Fuente: arXiv
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Main Authors: Barborini, Matteo, Charry, Jorge, Ditte, Matej, Leventis, Andronikos, Kafanas, Georgios, Tkatchenko, Alexandre
Format: Preprint
Published: 2025
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author Barborini, Matteo
Charry, Jorge
Ditte, Matej
Leventis, Andronikos
Kafanas, Georgios
Tkatchenko, Alexandre
author_facet Barborini, Matteo
Charry, Jorge
Ditte, Matej
Leventis, Andronikos
Kafanas, Georgios
Tkatchenko, Alexandre
contents We present the first open access version of the QMeCha (Quantum MeCha) code, a quantum Monte Carlo (QMC) package developed to study many-body interactions between different types of quantum particles, with a modular and easy-to-expand structure. The present code has been built to solve the Hamiltonian of a system that can include nuclei and fermions of different mass and charge, e.g. electrons and positrons, embedded in an environment of classical charges and quantum Drude oscillators. To approximate the ground state of this many-particle operator, the code features different wavefunctions. For the fermionic particles, beyond the traditional Slater determinant, QMeCha also includes Geminal functions such as the Pfaffian, and presents different types of explicit correlation terms in the Jastrow factors. The classical point charges and quantum Drude oscillators, described through different variational ansätze, are used to model a molecular environment capable of explicitly describing dispersion, polarization, and electrostatic effects experienced by the nuclear and fermionic subsystem. To integrate these wavefunctions, efficient variational Monte Carlo and diffusion Monte Carlo protocols have been developed, together with a robust wavefunction optimization procedure that features correlated sampling.
format Preprint
id arxiv_https___arxiv_org_abs_2511_03439
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle QMeCha: quantum Monte Carlo package for fermions in embedding environments
Barborini, Matteo
Charry, Jorge
Ditte, Matej
Leventis, Andronikos
Kafanas, Georgios
Tkatchenko, Alexandre
Chemical Physics
We present the first open access version of the QMeCha (Quantum MeCha) code, a quantum Monte Carlo (QMC) package developed to study many-body interactions between different types of quantum particles, with a modular and easy-to-expand structure. The present code has been built to solve the Hamiltonian of a system that can include nuclei and fermions of different mass and charge, e.g. electrons and positrons, embedded in an environment of classical charges and quantum Drude oscillators. To approximate the ground state of this many-particle operator, the code features different wavefunctions. For the fermionic particles, beyond the traditional Slater determinant, QMeCha also includes Geminal functions such as the Pfaffian, and presents different types of explicit correlation terms in the Jastrow factors. The classical point charges and quantum Drude oscillators, described through different variational ansätze, are used to model a molecular environment capable of explicitly describing dispersion, polarization, and electrostatic effects experienced by the nuclear and fermionic subsystem. To integrate these wavefunctions, efficient variational Monte Carlo and diffusion Monte Carlo protocols have been developed, together with a robust wavefunction optimization procedure that features correlated sampling.
title QMeCha: quantum Monte Carlo package for fermions in embedding environments
topic Chemical Physics
url https://arxiv.org/abs/2511.03439