Information-theoretic appraisal of electron densities.

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 the 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.