TOPOLOGICALLY PARTITIONED DYNAMIC POLARIZABILITIES USING THE THEORY OF ATOMS IN MOLECULES

Frequency-dependent distributed polarizabilities have been determined from time-dependent Hartree-Fock calculations, using the partitioning of the molecular space suggested by Bader's topological theory of atom s in molecules. The basis set dependence of the distributed dynamic po larizabilities is analyzed in terms of the first few Cauchy moments, f or the carbon monoxide, water, cyanogen, urea and benzene molecules. T wo alternative relocalization schemes have been considered in order to reduce the number of distributed dynamic polarizability parameters. T he first one, closely related to the atomic polarizability model of Ba der, leads to atomic charge-dipole and dipole-dipole polarizabilities, describing the response of the molecular charge distribution to a uni form external field, in terms of atomic charges and dipoles. The secon d scheme, similar to that suggested by Stone, retains the fully distri buted description of the dynamic charge-flow polarizabilities, while a ll two-center dipole-dipole and charge-dipole contributions are conden sed in one-center dynamic dipole-dipole polarizabilities.