Global hybrid multiconfiguration pair-density functional theory

TL;DR

This paper introduces a global hybrid multiconfiguration pair-density functional theory that combines local and nonlocal exchange interactions to efficiently handle static and dynamic correlations in strongly correlated systems.

Contribution

It develops a new {bb}-MCPDFT method that integrates v2RDM-driven CASSCF with pair-density functionals, improving computational efficiency and accuracy.

Findings

Successfully applied to molecular nitrogen dissociation

Accurately modeled water double dissociation

Predicted O3 cycloaddition reactions effectively

Abstract

A global hybrid extension of variational two-electron reduced-density matrix (v2RDM)-driven multiconfiguration pair-density functional theory (MCPDFT) is developed. Using a linear decomposition of the electron-electron repulsion term, a fraction {\lambda} of the nonlocal exchange interaction, obtained from v2RDM-driven complete active-space self-consistent field (CASSCF) theory, is combined with its local counterpart, obtained from an on-top pair-density functional. The resulting scheme (called {\lambda}-MCPDFT) inherits the benefits of MCPDFT (e.g., its simplicity and the resolution of the symmetry dilemma), and, when combined with the v2RDM approach to CASSCF, {\lambda}-MCPDFT requires only polynomially scaling computational effort. As a result, it can efficiently describe static and dynamical correlation effects in strongly correlated systems. The efficacy of the approach is assessed for several challenging multiconfigurational problems, including the dissociation of molecular nitrogen, the double dissociation of a water molecule, and the 1,3-dipolar cycloadditions of ozone to ethylene and ozone to acetylene in the O3ADD6 benchmark set.