Knowledge Bank

A configuration interaction calculation has been carried out for the $\mathrm{<mrow\; data-mjx-texclass="ORD">1</mrow>}\Sigma +$ ground state of $HeH+$ using as a basis functions in elliptical (prolate spheroidal) coordinates. Several internuclear distances have been considered and angular terms have been included. The results will be discussed in terms of correlation energies and natural spin orbitals.