Quadrupole polarizabilities of anions in crystals

Abstract

An implementation of coupled Hartree-Fock theory for static quadrupolar perturbations is used to calculate the quadrupole polarizability C and mixed dipole-quadrupole hyperpolarizability B for anions in crystals. The ions studied are F- in LiF and NaF, O2- in MgO, S2- in MgS, H- in LiH, and C4- in Be2C. In-crystal compression produces a more than fourfold reduction in C(F-) to 9·7 a.u. in LiF and 11·6 a.u. in NaF, and nominally infinite reductions for O2- and S2-. Low anisotropies ΔC indicate retention of approximate spherical symmetry for all but C4-. The hyperpolarizability B shows similar reductions. Implications for quadrupolar shell models of Cauchy violation are discussed.