Excited States from Quasiparticle Hamiltonian Based on Density Functional Theory

TL;DR

This paper introduces an extended quasiparticle Hamiltonian method based on density functional theory, improving the description of electronic excitations beyond traditional single-determinant approaches.

Contribution

The authors develop a quasiparticle Hamiltonian extension of occupancy extrapolation, enabling multi-configurational electronic excitation calculations with improved accuracy.

Findings

Method performs comparably to Bethe-Salpeter equation for valence singlet and charge-transfer excitations.

Method outperforms Bethe-Salpeter in valence triplet and Rydberg states.

Supports broad applicability and accuracy of the new approach.

Abstract

Recent advances in occupancy extrapolation (OE) show that potential of orbital-occupation based energy functions can describe electronic excitations. Here, the OE method in the particle-hole channel is extended to an effective quasiparticle Hamiltonian, enabling a multi-configurational description beyond single-determinant OE and $\Delta$SCF. The method performs comparably to the Bethe-Salpeter equation for valence singlet and charge-transfer excitations, and better for valence triplet and Rydberg states, supporting its accuracy and broad applicability.