Relativistic all-electron Dirac-Fock-Breit calculations on xenon fluorides (XeFn, n=1, 2, 4, 6)

The MOLFDIR package of programs is used to perform fully relativistic all-electron Dirac-Fock and Dirac-Fock-Breit calculations for the the XeFn (n = 1, 2, 4, 6) molecules assuming experimental symmetries. The Xe-F bound length for XeF2, XeF4, and XeF6 is optimized and the total ground-state energies are reported. The variation of the relativistic energy and the Breit correction with the internuclear distance is plotted. The role of relativistic corrections in the proper prediction of the Xe-F distance and the dissociation energy of the molecule is discussed. The problem of the reduction of the number of scalar two-electron integrals is studied. Our results illustrate the possibilities, difficulties, and limitations of the finite basis Dirac-Fock calculations for polyatomic molecules of different symmetries. (C) 1997 by John Wiley & Sons, Inc.