Journal of Physics B: Atomic, Molecular and Optical Physics
A double basis set in Hylleraas coordinates is used to obtain improved variational upper bounds for the nonrelativistic energy of the 1 1S (v = 0, R = 0), 2 1S (v = 1, R = 0) and 2 3P (v = 0, R = 1) states of H2 +. This method shows a remarkable convergence rate for relatively compact basis set expansions. A comparison with the most recent work is made. The accuracy of the wavefunctions is tested using the electron-proton Kato cusp condition.
Cassar, M. M. and Drake, Gordon W. F.. (2004). High precision variational calculations for H2 +. Journal of Physics B: Atomic, Molecular and Optical Physics, 37 (12), 2485-2492.