Reliable transition properties from excited-state mean-field calculations

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.