Accurate electron densities from quantum Monte Carlo calculations using real-space grids DOI
Alexander Kaiser, Stephan Kümmel

The Journal of Chemical Physics, Journal Year: 2025, Volume and Issue: 162(13)

Published: April 7, 2025

We provide accurate energies and electronic densities for Li2, C, N2 from the diffusion Monte Carlo (DMC) method in fixed node approximation based on orbitals a real-space grid approach. With relatively simple single-determinant trial wave functions, we demonstrate benefits of an all-electron approach conjunction with highly calculating that build determinant. Our DMC ground state match those more elaborate single-reference quantum (QMC) methods orbital basis sets. The binning technique is revisited to calculate density spatial grid. examine dependence resulting mixed estimator extrapolated function, specifically functional generating orbitals, by employing two distinctly different functionals, namely, local exact-exchange functional. Residual statistical artifacts QMC are readily corrected using regularization method, smooth densities. As example insight can be gained density, verify carbon atom, along one specific direction have asymptotic decay differs found all other directions. relate this observation previously published work, which discussed implications such nodal feature may exact Kohn–Sham potential.

Language: Английский

Understanding the Core Limitations of Second-Order Correlation-Based Functionals Through: Functional, Orbital, and Eigenvalue-Driven Analysis DOI Creative Commons
Aditi Singh, Eduardo Fabiano, Szymon Śmiga

et al.

Journal of Chemical Theory and Computation, Journal Year: 2025, Volume and Issue: unknown

Published: March 7, 2025

Density functional theory has long struggled to obtain the exact exchange-correlational functional. Numerous approximations have been designed in hope of achieving chemical accuracy. However, designing a involves numerous methodologies, which greater possibility for error accumulation if functionals are poorly formulated. This study aims investigate performance and limitations second-order correlation within framework density theory. Specifically, we focus on three major classes that incorporate energy expressions: ab initio (primarily Görling-Levy) functionals, adiabatic connection models, double-hybrid functionals. The principal objectives this research evaluate accuracy understand how choice reference orbitals eigenvalues affects these identify intrinsic expressions, especially when using arbitrary or noncanonical configurations, propose strategies improving their By addressing questions, aim provide deeper insights into factors governing thereby guiding future development.

Language: Английский

Citations

1
Accuracy of charge densities in electronic structure calculations DOI Creative Commons
Moritz Gubler, Moritz R. Schäfer, Jörg Behler

et al.

The Journal of Chemical Physics, Journal Year: 2025, Volume and Issue: 162(9)

Published: March 3, 2025

Accurate charge densities are essential for reliable electronic structure calculations because they significantly impact predictions of various chemical properties and, in particular, according to the Hellmann–Feynman theorem, atomic forces. This study examines accuracy obtained from different density functional theory (DFT) exchange–correlation functionals comparison with coupled cluster single and double excitations. We find that modern DFT can provide highly accurate densities, particularly case meta-generalized gradient approximations hybrid functionals. In connection Gaussian basis sets, it is necessary use largest sets available obtain nearly free set errors. These findings highlight importance selecting appropriate computational methods generating high-precision which are, instance, needed generate reference data training machine learned potentials.

Language: Английский

Citations

0
Accurate electron densities from quantum Monte Carlo calculations using real-space grids DOI
Alexander Kaiser, Stephan Kümmel

The Journal of Chemical Physics, Journal Year: 2025, Volume and Issue: 162(13)

Published: April 7, 2025

We provide accurate energies and electronic densities for Li2, C, N2 from the diffusion Monte Carlo (DMC) method in fixed node approximation based on orbitals a real-space grid approach. With relatively simple single-determinant trial wave functions, we demonstrate benefits of an all-electron approach conjunction with highly calculating that build determinant. Our DMC ground state match those more elaborate single-reference quantum (QMC) methods orbital basis sets. The binning technique is revisited to calculate density spatial grid. examine dependence resulting mixed estimator extrapolated function, specifically functional generating orbitals, by employing two distinctly different functionals, namely, local exact-exchange functional. Residual statistical artifacts QMC are readily corrected using regularization method, smooth densities. As example insight can be gained density, verify carbon atom, along one specific direction have asymptotic decay differs found all other directions. relate this observation previously published work, which discussed implications such nodal feature may exact Kohn–Sham potential.

Language: Английский

Citations

0