Calculated static and dynamic properties of solid α-F2

Abstract

The equilibrium structure and orientations of soid fluorine are calculated at zero temperature and pressure by completely optimizing a general monoclinic lattice with two molecules per unit cell. In addition to the lattice parameters and orientations, the molar volume, sublimation energy, and gas phase second virial coefficients are calculated. The k=0 libron and phonon frequencies are calculated using a lattice dynamics procedure, based upon the optimized structure. Both the proposed C2/c and C2/m structures are found for which nearly identical sublimation energies are calculated. Consequently, we are unable to resolve the controversy concerning which structure should be physically realized, although the C2/c structure gives slightly better overall agreement with experiment. The predicted results are found to be very sensitive to the magnitude of the quadrupole moment θ, which is taken to be 0.65×10−26 esu cm2 in this work.