A Theoretical Study of the Crystal HgCl2 Compound

Abstract

Abstract A theoretical study of the crystal HgCl2 compound has been done using a quasi-relativistic density-functional method. The crystalline environment was simulated by a cut-off type Madelung potential. Bond length, dissociation energy, force constants, and sublimation enthalpy are calculated. The calculated properties are in goon agreement with available experimental data. The calculated difference in bond length between the isolated and crystalline molecule is consistent with the data obtained by the more recent gas-phase electron diffraction and X-ray single crystal measurements. The predicted symmetrical and antisymmetrical force constants (ks, kas) and their trend (kas > ks) are in accordance with the Raman and IR data. The trend is in contrast to the free molecule case, where kas < ks. The sublimation enthalpies of hypothetical HgX2 (X = F, Cl, Br, I) compounds with the XeF2-type structure are evaluated. It is shown that the XeF2-type structures for HgX2are significantly less stable than the actual structures.