Some Excited States of the Hydrogen Molecule. I. 1Π<i>u</i>(1<i>s</i>2<i>p</i>Π) and 3Π<i>u</i>(1<i>s</i>2<i>p</i>Π)

Abstract

Theoretical potential curves, spectroscopic constants, and expectation values for some one-electron operators are given for the 3Πu(1s2pΠ) (metastable) and 1Πu(1s2pΠ) states of the hydrogen molecule. Total energies of 0.7145 and 0.7334 a.u. are obtained for 1Πu and 3Πu, respectively. The experimental total energies are 0.7186 and 0.7381 a.u. for 1Πu and 3Πu, respectively. The maximum in the potential curve of the 1Πu 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 1Πu curve is reasonably consistent with the observed data of Herzberg and Monfils.