Nonadiabatic generator-coordinate calculation ofH2+

We report on a nonadiabatic calculation of the few lowest $J=0\mathrm{}$ states in the ${\mathrm{H}}_2^{+}$ molecule done within the framework of the generator-coordinate method. Substantial accuracy is achieved with the diagonalization of matrices of very modest dimensions. The resulting wave functions are strongly dominated by just a few basis states. The computational scheme is set up so as to take the best advantage of good analytical approximations to existing adiabatic molecular wave functions.