Explicitly correlated configuration interaction studies using spherical Gaussians. II. Exploratory studies on LiH

✍ Scribed by K. M. Karunakaran; Ralph E. Christoffersen

• Publisher: John Wiley and Sons
• Year: 1982
• Tongue: English
• Weight: 531 KB
• Volume: 22
• Category: Article
• ISSN: 0020-7608
• DOI: 10.1002/qua.560220103

✦ Synopsis

Abstract

Ab initio self‐consistent‐field and configuration interaction studies have been carried out on the ground state of the LiH molecule at its equilibrium distance. Floating spherical Gaussian basis orbitals (FSGO) were employed, along with spherical Gaussian correlation factors, using the procedure described in the preceding paper. A near‐Hartree–Fock function was found using only 13 FSGO. Exploratory configuration interaction studies recovered approximately 73% of the inner shell correlation energy and approximately 56% of the total correlation energy with five configurations plus the Hartree–Fock configuration. These studies indicate that, by using spherical Gaussian correlation factors, direct introduction of interelectronic coordinates into trial wave functions can be accomplished for molecular systems. It was also shown that correlating configurations need not utilize the full Hartree–Fock basis, but may use substantially smaller bases and still recover correlation energy effectively. Finally, the results indicate that, in spite of their improper cusp behavior, FSGOS and spherical Gaussian correlation factors can be used for construction of high accuracy wave functions.