Solvation model effects on the static first hyperpolarizability of a push–pull π-conjugated molecule

In this work, we presented the results of density functional theory calculations for the static first hyperpolarizability for one representative push–pull π-conjugated molecule, 2-dimethylamino-7-nitrofluorene, in six organic solvents (p-dioxane, chloroform, tetrahydrofuran, acetone, acetonitrile, and dimethylsulfoxide) spanning a large range of dielectric constant. The finite-field formalism was used to calculate the longitudinal component of the static first hyperpolarizability. The solvent effect was calculated using two distinct polarizable continuum solvation models: the linear response and the state-specific polarizable continuum models. The calculations demonstrated the existence of solvation model effects on the property of interest, which warranted further analysis. The two-level model was then employed to illustrate the impact of solvation model. Our findings suggested that the state-specific polarizable continuum model gave a decrease of the dipole moment of the excited state in high polarity solvent for a bathochromic molecule whose excited state should have a larger polarization than its ground state.