THE POTENTIAL ENERGY CURVE OF THE B $^{1}\Sigma_{u}^{+}$ STATE OF $H_{2}$

Author Institution: Department Chemistry, University of IowaThe potential energy curve of the B $^{1}\Sigma_{u}^{+}$ state of $H_{2}$ has been obtained by accurate ab initio $calculation^{1}$ and by the Rydberg-Klein-Rees (RKR) $method.^{2}$ However, the ab initio potential is less accurate outside $4a_{0}$ (because a smaller basis set is used) and has not been calculated outside $12a_{0}$. Moreover, the RKR potentials used as input ``deperturbed’’ $B_{v}$ values, which must be considered rather uncertain because of the strong perturbation by the C $^{1}\Pi_{u}$ state. Thus a new hybrid potential has been constructed using the ab initio results for the inner wall $r_-(E)$ and for the outer branch $r_+(E)$ to $4a_{0}$, and using just the RKR equation for $r_+(E) - r_- (E)$ (which depends only on the unperturbed (i.e. $J = 0$) vibrational spacings) to obtain $r_+(E)$ out to the long-range region. Calculation of the eigenvalues of this potential is in progress. Preliminary results indicate improved agreement $(-1 cm^{-1})$ with experimental vibrational $spacings.^{1}$ W. Kolos and L. Wolniewicz, J. Chem. Phys. 45, 509 (1966);48, 3672 (1968). $^{2}$ T. Namioka, J. Chem. Phys. 43, 1636 (1965); A. Monfils, Bull. Acad. Roy. Belg., Cl. Sci. [5], 54, 44 (1968); R. J. Spindler, JR., J. Quant. Spectrosc. Radiat. Transfer 9, 597 (1969)