Copyright © 2007 American Chemical Society
Web Release Date: September 13,
All-Electron First Principles Calculations of the Ground and Some Low-Lying ExcitedStates of BaI
Laboratory of Physical Chemistry, Department of Chemistry, National and Kapodistrian University of Athens,P.O. Box 64 004, 157 10 Zografou, Athens, Greece
Received: June 13, 2007
In Final Form: July 18, 2007
The electronic structure of the heavy diatomic molecule BaI has been examined for the first time by ab initiomulticonfigurational configuration interaction (MRCI) and coupled cluster (RCCSD(T)) methods. The effectsof special relativity have been taken into account through the second-order Douglas-Kroll-Hess approximation. The construction of (,) potential energy curves allows for the estimation of "experimental"dissociation energies (De) of the first few excited states by exploiting the accurately known De experimentalvalue of the X2+ ground state. All states examined are of ionic character with a Mulliken charge transfer of0.5 e- from Ba to I, and this is reflected to large dipole moments ranging from 6 to 11 D. Despite theinherent difficulties of a heavy system like BaI, our results are encouraging. With the exception of bonddistances that on the average are calculated 0.05 Å longer than the experimental ones, common spectroscopicparameters are in fair agreement with experiment, whereas De values are on the average 10 kcal/mol smaller.