GAUSSIAN FUNCTIONS IN HYLLERAAS-CONFIGURATION-INTERACTION CALCULATIONS .6. THE 1ST EXCITED-STATE OF H-3+

The Hylleraas-configuration-interaction (H-CI) method has been applied to the first 3-SIGMA-u+ excited state of the H3+ molecular ion. Besides the ground state, this is the only known bound state of H3+, albeit with a very weak minimum of 8.428 kcal/mol. The equilibrium geometry and the minimum energy have been determined. The Hylleraas-CI energy of - 1.116 102 7 a.u. at an equidistant nuclear separation of 2.454 bohr is the lowest reported so far. The vibrational force constants and vibrational frequencies also have been computed.