COMPLETE ACTIVE-SPACE CONFIGURATION-INTERACTION WITH OPTIMIZED ORBITALS - APPLICATION TO LI2

We performed CAS-CI calculations on Li2 using a set of molecular orbit als (MO) optimized with a procedure that, in the case of highly symmet ric molecules, permits extraction of a small set of MO out of a large set of atomic orbitals (AO). The dimension of the CAS-CI space was of about 12 million symmetry-adapted determinants. We determined some spe ctrosopic constants of Li2 with three different atomic basis sets of i ncreasing quality. The values obtained with the largest atomic basis s et are very close to the experimental results. (C) 1995 John Wiley & S ons, Inc.