EXTENSION OF GAUSSIAN-2 THEORY TO MOLECULES CONTAINING 3RD-ROW ATOMS GA-KR

Gaussian-2 (G2) theory has been extended to molecules containing the t hird-row nontransition elements Ga-Kr. Basis sets compatible with thos e used in G2 theory for molecules containing first- and second-row ato ms have been derived. Spin-orbit corrections for atoms and molecules h aving spatially degenerate states (P-2, P-3 for atoms and (2) Pi for m olecules in this work) are included explicitly in the G2 energies. The average absolute deviation from experiment for 40 test reactions is 1 .37 kcal/mol. In contrast to the situation for first- and second-row m olecules, inclusion of spin-orbit effects is very important in attaini ng accurate energies for molecules containing third-row atoms. Without spin-orbit effects, the average absolute deviation is 2.36 kcal/mol. (C) 1995 American Institute of Physics.