. Author manuscript; available in PMC: 2009 Sep 9.

Published in final edited form as: J Chem Theory Comput. 2008 Sep 9;4(9):1409–1422. doi: 10.1021/ct800109s

Table 5.

Computed ground state energies (kcal/mol) for hydrogen chloride, hydrogen fluoride, and hydrogen molecules from the Morse potential using the harmonic approximation Rayleigh-Ritz (RR) variational approach, second-order Rayleigh-Schrödinger perturbation theory (RS2), and first and second orders of the Kleinert variational perturbation theory (KP1 and KP2)

Molecule	Quantum	Harmonic	RR	RS2	KP1/P10-0.02A	KP2/P10-0.02A
HCl	4.231	4.274	4.348	4.238	4.253	4.234
HF	5.732	5.793	5.899	5.742	5.762	5.736
H₂	6.193	6.284	6.437	6.213	6.238	6.202