The hyperpolarizability of the tricyanomethanide molecular ion in solution

Considering the tricyanomethanide ion [C(CN)3]− as a prototype for octopole-like molecules we explore the solvent, correlation and frequency dependences of its polarizability and first hyperpolarizability using a reaction field response model with single- and multiconfigurational self-consistent wavefunctions. The convention problem of relating the hyperpolarizability obtained from the hyper-Rayleigh scattering technique and from computations is disentangled. The validity of the simplifying two- and three-state models for the hyperpolarizability are examined.