On the importance of excited state dynamic response electron correlation in polarizable embedding methods
We investigate the effect of including a dynamic reaction field at the lowest possible ab inito wave function level of theory, namely the Hartree Fock (HF) self consistent field level within the polarizable embedding (PE) formalism. We formulate HF based PE within the linear response theory picture leading to the PE random phase approximation (PE RPA) and bridge the expressions to a second order polarization propagator approximation (SOPPA) frame such that dynamic reaction field contributions are included at the RPA level in addition to the static response described at the SOPPA level but with HF induced dipole moments. We conduct calculations on para nitro aniline and para nitro phenolate using said model in addition to dynamic PE RPA and PE CAM B3LYP. We compare the results to recently published PE CCSD data and demonstrate how the cost effective SOPPA based model successfully recovers a great portion of the inherent PE RPA error when the observable is the solvatochromic shift. We furthermore demonstrate that whenever the change in density resulting from the ground state excited state electronic transition in the solute is not associated with a significant change in the electric field, dynamic response contributions formulated at the HF level of theory manage to capture the majority of the system response originating from derivative densities. (c) 2012 Wiley Periodicals, Inc.
J. Comput. Chem.