L. Joubert et al., STRUCTURAL AND THERMOCHEMICAL AB-INITIO STUDIES OF LANTHANIDE TRIHALIDE MOLECULES WITH PSEUDOPOTENTIALS, Inorganic chemistry, 37(8), 1998, pp. 1984-1991
Structural and vibrational frequency studies have been carried out for
30 lanthanide trihalide molecules LnX(3) (Ln = La-Lu; X = Cl, F) usin
g ab initio quasi-relativistic effective core potentials at Hartree-Fo
ck and Moller-Plesset post-Hartree-Fock levels of theory. A planar D-3
h geometry was obtained for all trichloride molecules. In accordance w
ith previous theoretical works, a C-3v, structure was clearly establis
hed for the majority of the trifluorides. Calculated bond lengths and
vibrational frequencies are in good agreement with the experimental da
ta. Therefore, thermochemical functions have been estimated from therm
ostatistics calculations combined with our quantum mechanics results.
The electronic partition function is crucial in order to be in accorda
nce with experimental data tables, especially for temperatures higher
than 500 K. A simple example of thermochemical equilibrium clearly pro
ves the validity of the estimated functions in the case of the lanthan
um halides.