Hexadecapole moment, dipole and quadrupole polarizability of sulfur hexafluoride

We have obtained SCF and MP2 values for the polarizability and hyperpolariz ability of sulfur hexafluoride. A large [8s6p5d2f/6s4p4d1f] basis set, cons isting of 335 Gaussian-type functions, provides near-Hartree-Fock values fo r all properties of interest: -24.76 ea(0)(4) for the hexadecapole moment ( Phi), 26.54 e(2)a(0)(2)E(h)(-1) for the dipole polarizability (alpha), gamm a(zzzz); = 738, gamma(xxzz) = 317 and <(gamma)over bar> = 823 e(4)a(0)(4)E( h)(-3) for the dipole hyperpolarizabilily, 227.5 e(2)a(0)(4)E(h)(-1) for th e mean quadrupole polarizability ((C) over bar), 101.7 e(2) a(0)(4) E-h(-1) for the dipole-octopole polarizability (E) and B-zz,B-zz = - 134, B-xz,B-x z = - 156 e(3) a(0)(4) E-h(-2) for the dipole-dipole-quadrupole hyperpolari zability. At MP2 level the dipole polarizability varies with the S-F bond l ength (symmetric stretch) as [alpha(R)- alpha(R-0)]/e(2)a(0)(2) E-h(-1) = 2 5.38 Delta R + 13.72 Delta R-2 - 0.99 Delta R-3 where Delta R/a(0) = (RS-F - R-0) and R, is the experimental S-F separation. The value of Phi is lower than any experimental result, and E is lower than the best experimental es timate. (C) 1999 Elsevier Science B.V. All rights reserved.