Time-dependent Electronic Populations in Fragment-based Time-dependent Density Functional Theory

TL;DR

This paper introduces a formally exact time-dependent density-functional theory framework for molecular fragments with variable electrons, enabling better modeling of chemical bond dynamics and providing a stable density-inversion method applicable to various DFT extensions.

Contribution

It extends previous work by developing a formalism for electronic dynamics of molecular fragments with variable electrons and introduces a stable density-inversion method for time-dependent and ground-state DFT.

Findings

Formal exact TDDFT for molecular fragments with variable electrons.

New stable density-inversion method for TDDFT and ground-state DFT.

Enhanced modeling of chemical bond formation and breaking.

Abstract

Conceiving a molecule as composed of smaller molecular fragments, or subunits, is one of the pillars of the chemical and physical sciences, and leads to productive methods in quantum chemistry. Using a fragmentation scheme, efficient algorithms can be proposed to address problems in the description of chemical bond formation and breaking. We present a formally exact time-dependent density-functional theory for the electronic dynamics of molecular fragments with variable number of electrons. This new formalism is an extension of previous work [Phys. Rev. Lett. {\bf 111}, 023001 (2013)]. We also introduce a stable density-inversion method that is applicable to time-dependent and ground-state density-functional theory, and their extensions, including those discussed in this work.