  Delta-self-consistent field theory (delta-SCF) is a conceptually simple and
computationally inexpensive method for finding excited states. Using the
maximum overlap method to guide optimization of the excited state, delta-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
delta-SCF on a larger set of molecules than has previously been considered,
and, in particular, we examine the performance of delta-SCF in predicting
transition dipole moments, the essential quantity for spectral intensities. A
potential downfall for delta-SCF transition dipoles is origin dependence
induced by the nonorthogonality of delta-SCF ground and excited states. We
propose and test the simplest 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.
