Visual and Computational Comparison of Functionals Used in Density Functional Theory

This work presents the visual and quantitative comparison of Density Functional Theory (DFT) exchange-correlation energy E_xc functionals with Coupled Cluster with Single and Double excitations (CCSD) calculations (and experiment where possible). The E_xc functional is an approximate term which is a component of the total energy of a molecule. This comparison is based on visualizing the differences of computed properties, such as the charge density, geometry and other molecular properties between the functional and a CCSD calculation. In this work, this visual comparison for a set of functionals using a set of small molecules is presented to elucidate the method. Specifically, this visual comparison of the local molecular properties includes the charge density and electron localization function and global molecular properties such as molecular geometry for each DFT functional compared with a CCSD calculation. Note, that the differences of the particular computed properties are computed visually.