Knowledge Bank

“A configuration interaction study of the ground state of the $H2$ molecule has been made, using approximate LCAO molecular orbitals to build various $\mathrm{<mrow\; data-mjx-texclass="ORD">1</mrow>}\Sigma g+$ wave functions. The forms of the molecular orbitals are $\sigma a,u-(1/2)(\chi a\pm \chi b$ and $\pi \mu ,ϵ=(1/2)(2p\pi a\pm 2p\pi b)$ where $\chi$ represents a 1s, 2s, or $2p\sigma$ Slater atomic orbital. Computations have been made with up to 12 configurations, using the 1103 digital computer at Wright-Patterson Air Force Base. The configurations and the effective nuclear charges were chosen to reduce the correlation energy as much as possible. To this end, open-shell configurations were also used; e.g. $[\sigma g1s(1)\sigma g1s\prime (2)+\sigma g1s\prime (1)\sigma g1s(2)]$ where $\zeta 1s\ne \zeta 1s\prime$. Computations varying the $\zeta \prime s$ are still in progress. The best result to date, obtained with 10 configurations, yields a binding energy of 4.52 e.v., compared with an experimental value of 4.72 e.v.”