High-temperature infrared spectra of rare-earth trihalides. Part II. Re-interpretation of the infrared spectra of CeCl 3, NdCl 3, SmCl 3, GdCl 3 and DyCl 3 using ab initio molecular orbital calculations

Abstract

Ab initio molecular orbital calculations have been carried out for the rare earth trichlorides CeCl 3, NdCl 3, SmCl 3, GdCl 3, DyCl 3 at the MP2 level of theory supplemented with quasirelativistic effective core potentials and (7s6p5d)/[5s4p3d]-GTO valence basis sets for the rare earth atoms. The computations indicated that the molecules have a flat potential energy surface around the global minimum. The ab initio vibrational analyses indicated that only two of the four fundamentals ( v 2 and v 3) have a significant intensity in the infrared spectra. Combining the results of the computations with an analysis of the rotational contours, the results of our previous infrared spectroscopy experiments have been re-interpreted and the v 2 and v 3 fundamentals have been assigned.