Information-Theoretic Appraisal of Electron Densities

TL;DR

This paper uses information-theoretic measures to evaluate and compare electron densities in atoms and molecules, providing new benchmarks and insights for quantum chemistry methods.

Contribution

It introduces the use of information entropy and divergence metrics, like J-divergence, for benchmarking electron densities against high-level references and analyzing density changes.

Findings

J-divergence effectively benchmarks densities against coupled cluster and CI references.

Information measures reveal differences between mean-field and correlated orbitals.

Entropic analysis correlates with the accuracy of computed molecular properties like dipole moments.

Abstract

We present an information-theoretic assessment of atomic and molecular densities in the ground state and under a range of physical scenarios--excitation, confinement, and ensemblization. Comparisons across densities obtained from single-reference methods are facilitated through information entropy measures evaluated in position space. We demonstrate that the J-divergence serves as a key metric for benchmarking electron densities against coupled cluster and configuration interaction references. Mean-field orbital information is further compared with that of Brueckner and Dyson orbitals, and informational changes in multiple self-consistent-field solutions are examined under various symmetry-breaking conditions. We also explore the relationship between entropic measures of electron delocalization and the accuracy of the CO dipole moment computed with different methods. Our work offers insights into the selection of optimal reference determinants for a given chemical application and highlights potential benefits of incorporating information-entropy concepts in the development of new density functionals.