Polarisability of the bromide anion in NaBr. Parameters for simulation of molten NaBr

Abstract

Ab initio coupled Hartree–Fock calculations on Br– in NaBr give a polarisability of 27.6 a.u., a reduction of more than 35% from the free-ion value. Electron correlation, approximated by Moller–Plesset theory, adds 1 a.u. and brings the calculated bromide polarisability to within 1% of the value derived from the experimental refractive index of the solid. Polarisability derivatives with respect to nearest-neighbour displacements are calculated and interpreted in terms of changes in the confining potential well of a distorted solid.