Delta-self-consistent field theory (∆SCF) is a conceptually simple and computationally in- expensive method for finding excited states. Using the maximum overlap method to guide optimization of the excited state, ∆SCF has been shown to predict excitation energies with a level of accuracy that is competitive with, and sometimes better than, that of TDDFT. Here we benchmark ∆SCF on a larger set of molecules than has previously been considered, and, in particular, we examine the performance of ∆SCF in predicting transition dipole moments, the essential quantity for spectral intensities. A potential downfall for ∆SCF transition dipoles is origin dependence induced by the nonorthogonality of ∆SCF ground and excited states. We propose and test a simple correction for this problem, based on symmetric orthogonalization of the states, and demonstrate its use on bacteriochlorophyll structures sampled from the photosynthetic antenna in purple bacteria.
Bibliographical noteFunding Information:
We gratefully acknowledge the funding agencies that supported this work: O.F. was funded by the U.S. Department of Energy (Grant No. DE-FOA-0001912). S.B.W. was supported by a research fellowship from the Royal Commission for the Exhibition of 1851. We are grateful for a comment from Diptarka Hait pointing out that the transition dipole can alternatively be evaluated by aligning the molecular center of charge with the origin. F.R.M. is the co-founder and CTO of Entos, Inc. The other authors declare no conflict of interest.
© 2021 Author(s).