Vibrational analysis of TeCl4 .2. A Hartree-Fock, MP2, and density functional study

The geometry and vibrational spectrum of TeCl4 was calculated with various quantum chemical methods [Hartree-Fock, second-order Moller-Plesset (MP2) and generalized gradient approximation density functional theory (GGA-DFT)]. Five different basis-set combinations were tested: the relativistic effective core potentials with double-zeta split valence basis (RECP) of Hay & Wadt (HW) and Stevens et al. (CEP); the above RECP basis sets extended with polarization functions for Te and using a 6-31G* basis for Cl (HW* and CEP*); a medium-size all-electron basis set (ALL). The quality of the calculated data was assessed by comparison with recent experimental results. The Hartree-Fock method combined with the HW and CEP I,asis sets provided a very good approximation of the experimental vibrational spectra. The quality of the results is comparable to those of the best methods (MP2, B3-P, B3-PW with HW* and CEP* and B3-LYP, B3-P, BS-PW with the ALL basis set). However, the HW and CEP basis sets provided very poor geometry and vibrational frequencies when they were used in combination with any correlated method in this work. Similarly, the DFT methods using Becke's 1988 exchange functional (B-LYP. B-P, B-PW) without the inclusion of the exact exchange let to very poor results with the basis sets used in this study. (C) 1997 John Wiley & Sons, Inc.