Density Functional Calculation of the Electronic Structure and Vibrational Spectroscopy of SbI₃ and BiI₃

The amsterdam density functional method （ADF） is used to calculate the electronic structures and vibrational spectroscopy of SbI₃, and BiI₃, at the level of STO-3ζ. The geometry optimization of BiI₃, were carried out at the level of compuational study of SbI₃ and BiI₃ with experimental geometry local density approximation employing STO-2ζ basis sets and STO-3ζ basis sets. The theoretical results indicate that the kinetic energy, the atomic net populations and overlap populations are influenced by the correlation effects of basis sets.
The theoretical data of vibrational spectra of SbI₃ and BiI₃ with experimental geometries are discrepanied the reported experimental results comparing with ah initio at the level of MP2. But the theoretical results of the four normal vibrational modes （IR active） of vibrational spectra of BiI₃ molecule with fall geometry optimization at the level of local density approximation with STO-3ζ basis sets are in good agreement with the experimental results reported by Hargitton et al., and the theoretical results also are influenced by the selected basis sets. It is found that the density functional theory can give a more reasonable explanation. Because the correlation effect is taken into consideration in density functional theory. The absorption strengths of the four normal vibrational modes are also reported.