Some Excited States of the Hydrogen Molecule. I. 1Πu(1s2pΠ) and 3Πu(1s2pΠ)

Abstract

Theoretical potential curves, spectroscopic constants, and expectation values for some one‐electron operators are given for the ³Π_u(1s2pΠ) (metastable) and ¹Π_u(1s2pΠ) states of the hydrogen molecule. Total energies of 0.7145 and 0.7334 a.u. are obtained for ¹Π_u and ³Π_u, respectively. The experimental total energies are 0.7186 and 0.7381 a.u. for ¹Π_u and ³Π_u, respectively. The maximum in the potential curve of the ¹Π_u state is found to be much smaller and to occur at a larger internuclear separation (0.02 eV at R≈8.5 a.u.) than estimated by previous theoretical calculations (0.1 eV at R≈4.5 a.u.). Our ¹Π_u curve is reasonably consistent with the observed data of Herzberg and Monfils.