In this paper we extend and apply the electrostatic model [Jortner, J.; Even, U.; Leutwyler, S.; Berkowitch-Yellin, Z. J. Chem. Phys. 1983, 78, 305] for the calculation of the ionization potentials of M.A(n) heteroclusters (M = benzene, anthracene (ANT) and 9,10-dichloroanthracene (DCA); A = Ar and Kr). The electrostatic contributions to the ionization potential shift delta-I of the heterocluster relative to the bare molecule (consisting of charge-induced dipole and induced dipole-induced dipole M+-A(n) and M-A(n) interactions) were evaluated using the entire pi and sigma-atomic charge densities of M+ and of M. Molecular wave functions for ANT, for DCA, and for their cations were computed using the semiempirical MNDO method and utilized for the computation of the atomic charges by the Mulliken and the Lowdin methods. The Lowdin charges provide the best description of delta-I. The modification of the calculated delta-I for benzene-Ar by the improvement of the molecular wave functions for benzene+ and benzene was also explored. The electrostatic model, together with structural data, accounts for the experimental delta-I data of benzene.Ar1, ANT.Ar1, ANT.Kr1, DCA.Ar1, and DCA.Kr1. The electrostatic model in conjunction with finite temperature molecular dynamics simulations accounts well for the size dependence of delta-I for DCA.AR(n) and DCA.Kr(n) (n = 1-18) heteroclusters.
