On The Inclusion of One Double Within CIS and TD-DFT

TL;DR

This paper introduces an improved method for optimizing frontier orbitals by including a double configuration, benchmarking its impact within CIS and TD-DFT calculations, showing significant qualitative improvements despite limited quantitative accuracy.

Contribution

The paper presents a novel approach to include a double configuration in orbital optimization and assesses its effects within CIS and TD-DFT methods.

Findings

Robust algorithm that improves qualitative results in electronic structure calculations.

Including a double configuration enhances the accuracy of excited state descriptions.

Method shows consistent qualitative improvements across test cases.

Abstract

We present an improved approach for generating a set of optimized frontier orbitals (HOMO and LUMO) that minimizes the energy of one double configuration. We further benchmark the effect of including such a double within a CIS or TD-DFT configuration interaction Hamiltonian for a set of test cases. We find that, although we cannot achieve quantitative accuracy, the algorithm is quite robust and routinely delivers an enormous qualitative improvement to standard single-reference electronic structure calculations.