The (2p2)3P state of H− and the convergence of the CI series

Abstract

A sequence of increasingly accurate configuration interaction (CI) wave functions is used to discuss binding and the convergence of the CI series for the (2p2)3P state of H−. We get an upper bound energy Eu=−0.1 253 547 166 a.u.(H), the lowest yet obtained, lying within an estimated 0.4 μhartree from the exact eigenvalue of Schrödinger’s nonrelativistic equation. The angular energy limits define angular energy increments ΔEl which follows the formula ΔEl?0.18 (l+1/2)−7a.u. for l?4. Five or eighty per cent of binding is obtained with a three-term Ψ=c1(2p)2+c2(2p′)2+c3 (3d)2 depending on whether the 2p,2p′, and 3d orbitals are energy optimized STO’s or accurate natural orbitals, respectively.