Short-Range Contributions to the Polarization of Cations

Charge-overlap cluster calculations [Wheatley, R. J. Chem. Phys. Lett . 1998, 294, 487], in which the electronic structure of a central ion is modified self-consistently by the frozen densities of its neighbors, are used to model induced dipoles in the condensed-phase alkali metal halides. Two distinct effects of overlap are identified: exchange-repulsion and Coulomb corrections. For anions, both substantially reduce the dipole from its asymptotic value; for cations, the two short-range effects are opposed, producing small net short-range corrections of different sign for different alkali metal cations.