FIRST EXCITED 1SIGMAG+ STATE OF HYDROGEN MOLECULE AND ITS ISOTOPES

A complete theoretical analysis of the first excited 1Σg+ state of the hydrogen molecule is presented. A linear variational method based on a James and Coolidge wave function was used to compute a potential curve for the electronic motion. The potential curve obtained has two minima. A 24-term wave function gave a potential minimum at R = 1.9 atomic units of -0.71749 a.u. as compared to the experimental value of -0.7181 a.u. A minimum energy of -0.70532 a.u. was obtained at R = 4.3 a.u. as compared to Davidson's calculated value of -0.70067 a.u. at R = 4.35 a.u. Using this potential curve vibrational and rotational levels were then computed for the hydrogen molecule and its isotopic species. The results for H2, D2, and T2 are compared with experimental values. The levels below the potential barrier were classified as belonging to the separate minima by examining the rotational differences and the wave functions for the nuclear motion. Above the barrier the probability density was approximately the same for both minima. © 1968.