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Complete active‐space configuration interaction with optimized orbitals: Application to Li 2
Author(s) -
Evangelisti Stefano,
Bendazzoli Gian Luigi,
Gagliardi Laura
Publication year - 1995
Publication title -
international journal of quantum chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.484
H-Index - 105
eISSN - 1097-461X
pISSN - 0020-7608
DOI - 10.1002/qua.560550309
Subject(s) - basis set , atomic orbital , chemistry , basis (linear algebra) , complete active space , molecular orbital , space (punctuation) , linear combination of atomic orbitals , slater type orbital , localized molecular orbitals , atomic physics , dimension (graph theory) , sto ng basis sets , set (abstract data type) , molecule , symmetry (geometry) , computational chemistry , molecular physics , physics , quantum mechanics , mathematics , density functional theory , combinatorics , geometry , computer science , programming language , operating system , electron , organic chemistry
We performed CAS – CI calculations on Li 2 using a set of molecular orbitals ( MO ) optimized with a procedure that, in the case of highly symmetric 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 spectroscopic constants of Li 2 with three different atomic basis sets of increasing quality. The values obtained with the largest atomic basis set are very close to the experimental results. © 1995 John Wiley & Sons, Inc.