Quantitative Accuracy in Calculating Charge Transfer State Energies in Solvated Molecular Complexes Using a Screened Range Separated Hybrid Functional within a Polarized Continuum Model

Abstract

A screened-range separated hybrid (SRSH) functional in combination with a polarized continuum model (PCM) was recently implemented within a consistent dielectric polarization treatment. The SRSH-PCM demonstrated excellent agreement of the calculated fundamental orbital gaps with measured energies in the condensed phase. Here we develop a linear response time-dependent DFT (TDDFT) approach to obtain solvated charge transfer state energies. We show that the calculated excited state energies of solvated electron-donor-acceptor complexes are in excellent agreement with measured benchmark values. Specifically we consider donor-acceptor complexes of functionalized anthracenes with tetracyanoethylene in methylene chloride. Our proposed SRSH-PCM calculated energies earn a mean absolute deviation (MAD) from the benchmark values as low as 0.04 eV with optimal tuning in PCM, whereas values based on simpler RSH-PCM, without proper treatment of dielectric screening, are associated with a 0.27 eV MAD.