Orbital Optimized Density Functional Theory for Electronic Excited States

TL;DR

This paper discusses the development and application of orbital optimized density functional theory (OO-DFT) as a promising alternative to traditional TDDFT for accurately modeling challenging electronic excited states in large systems.

Contribution

It introduces modern advancements in OO-DFT methods, demonstrating their effectiveness for complex excited states and highlighting their growing practical utility.

Findings

OO-DFT effectively models charge-transfer and doubly excited states.

Recent developments improve the efficiency and reliability of OO-DFT.

Applications show OO-DFT's practical success in large chemical systems.

Abstract

Density functional theory (DFT) based modeling of electronic excited states is of importance for investigation of the photophysical/photochemical properties and spectroscopic characterization of large systems. The widely used linear response time-dependent DFT (TDDFT) approach is however not effective at modeling many types of excited states, including (but not limited to) charge-transfer states, doubly excited states and core-level excitations. In this perspective, we discuss state-specific orbital optimized (OO) DFT approaches as an alterative to TDDFT for electronic excited states. We motivate the use of OO-DFT methods and discuss reasons behind their relatively restricted historical usage (vs TDDFT). We subsequently highlight modern developments that address these factors and allow efficient and reliable OO-DFT computations. Several successful applications of OO-DFT for challenging electronic excitations are also presented, indicating their practical efficacy. OO-DFT approaches are thus increasingly becoming a useful route for computing excited states of large chemical systems. We conclude by discussing the limitations and challenges still facing OO-DFT methods, as well as some potential avenues for addressing them.