ON THE CALCULATION OF LOCAL-FIELD FACTORS FOR MICROSCOPIC STATIC HYPERPOLARIZABILITIES OF MOLECULES IN SOLUTION WITH THE AID OF QUANTUM-MECHANICAL METHODS

We present a simple computational method to connect the computed nb in itio values of static dipole polarizabilities and hyperpolarizabilitie s of molecules in solution with their experimental counterparts, The c onnection is done in terms of local field factors, We show that formul as used by experimentalists are not adequate, and that thy can be repl aced by a reformulation of the quantum-mechanical codes for the calcul ation of (hyper)polarizabilities in solution by using a realistic desc ription of the solvent reaction field (i.e., a cavity with the proper molecular shape). This reformulation leads to an additional set of hyp erpolarizability values which lake into account local modifications to the external static field, This second set of values has a direct rel ation with the macroscopic susceptibility tensors and, when compared t o that derived from standard calculations, allows one to evaluate real istic local field factors.