Atomic and molecular applications of open-shell cluster expansion techniques with incomplete model spaces

Abstract

Pilot numerical applications are reported of two recently formulated cluster expansion formalisms that generate connected effective Hamiltonians even for incomplete model spaces. Results are presented for prototype systems such as (a) the He atom, (b) the H 2 molecule and (c) the He 2 2+ ion. For He and H 2 we give results for typical examples of incomplete model spaces, and for He 2 2+ we present adiabatic potential energy curves the first four 1Σ g + and the first two 3Σ g +states, calculated with an incomplete model space.