Topologically partitioned dynamic polarizabilities using the theory of atoms in molecules

Abstract

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 atoms in molecules. The basis set dependence of the distributed dynamic polarizabilities is analyzed in terms of the first few Cauchy moments, for the carbon monoxide, water, cyanogen, urea and benzene molecules. Two alternative relocalization schemes have been considered in order to reduce the number of distributed dynamic polarizability parameters. The first one, closely related to the atomic polarizability model of Bader, leads to atomic charge–dipole and dipole–dipole polarizabilities, describing the response of the molecular charge distribution to a uniform external field, in terms of atomic charges and dipoles. The second scheme, similar to that suggested by Stone, retains the fully distributed description of the dynamic charge-flow polarizabilities, while all two-center dipole–dipole and charge–dipole contributions are condensed in one-center dynamic dipole–dipole polarizabilities. Key words: Bader-partitioning, distributed dynamic polarizabilities, Cauchy-moments, benzene, polarizability of; urea, polarizability of.