Ab initio calculation of electronic states of the ions H4+ and H5+

Electronic state calculations for the ions H4+ (with symmetries D4 and C2v) and H (with symmetries D5 and D2d) are made using the valence‐bond method. All the configurations obtained from the given set of 1s‐functions of Slater type are taken into account. Space functions are used throughout the computation (“spin‐free quantum chemistry”). Preliminary quasidiagonalization of the secular equation is implemented by the construction of the multiplet eigenfunctions 2S+1Γ(α) from the initial variational functions. The results of the calculations are as follows: the ion H is unstable, the ion H is stable with equilibrium nuclear conformation of symmetry D2d and with the energy of dissociation into H and H2 near 4 eV.