Combining Localized Orbital Scaling Correction and Bethe-Salpeter Equation for Accurate Excitation Energies

TL;DR

This paper introduces a combined approach using localized orbital scaling correction (LOSC) with the Bethe-Salpeter equation (BSE) to predict molecular excitation energies more accurately and efficiently than traditional methods.

Contribution

The study demonstrates that integrating LOSC with BSE improves excitation energy predictions, outperforming standard $G_{0}W_{0}$ approaches and reducing computational costs.

Findings

BSE/LOSC outperforms BSE/$G_{0}W_{0}$ in excitation predictions.

BSE/LOSC achieves accuracy comparable to TDDFT and ev$GW$ methods.

BSE/LOSC reduces starting point dependence in calculations.

Abstract

We applied localized orbital scaling correction (LOSC) in Bethe-Salpeter equation (BSE) to predict accurate excitation energies for molecules. LOSC systematically eliminates the delocalization error in the density functional approximation and is capable of approximating quasiparticle (QP) energies with accuracy similar or better than the $GW$ Green's function approach and with much less computational cost. The QP energies from LOSC instead of commonly used $G_{0}W_{0}$ and ev$GW$ are directly used in BSE. We show that the BSE/LOSC approach greatly outperforms the commonly used BSE/$G_{0}W_{0}$ approach for predicting excitations with different characters. For the calculations for Truhlar-Gagliardi test set containing valence, charge transfer (CT) and Rydberg excitations, BSE/LOSC with the Tamm-Dancoff approximation provides a comparable accuracy to time-dependent density functional theory (TDDFT) and BSE/ev$GW$. For the calculations of Stein CT test set and Rydberg excitations of atoms, BSE/LOSC considerably outperforms both BSE/$G_{0}W_{0}$ and TDDFT approaches with a reduced starting point dependence. BSE/LOSC is thus a promising and efficient approach to calculate excitation energies for molecular systems.