PNNL

Abstract

The vertical excitation energies of low-lying excited states of the zinc-porphyrin molecule in aqueous solution are characterized using a combination of coupled cluster and molecular mechanics descriptions. Coupled cluster description of excited states is based on equation-of-motion approach with singles and doubles (EOMCCSD) as well as its non-iterative extension for triply excited configurations. These results are compared with those obtained with time-dependent density functional theory (TD-DFT), which experiences severe problems with adequate description of low-lying states of chargetransfer character.