A Simple One-Body Approach to the Calculation of the First Electronic Absorption Band of Water

摘要

A one-body decomposition approach for investigating the electronic absorption spectra of molecular systems was proposed and applied to water clusters (H20)" including up to N = 80 water molecules. Two specific aspects of the present implementation are the inclusion of the coupling between excited states and a simplified representation for the N-body Coulombic effects. For smaller clusters, the results based on the one-body decomposition scheme are in good agreement with full EOM-CCSD calculations. Two different regimes can be identified in the electronic absorption profile of larger water clusters. The first low-energy regime is dominated by local excitonic states on the cluster surface, whereas the higher-energy excitations associated with the second one are of delocalized nature.