Relativistic corrections, Born-Oppenheimer energies and adiabatic corrections are computed for R < 12.0 bohr for the electronic ground state of the hydrogen molecule. The Born-Oppenheimer potential is slightly lower than ever reported. The problem of linear dependencies in the basis set is removed and the same set is used for all internuclear distances which assures continuity of the results. The radiative corrections are evaluated approximately and-for that purpose-the polarizability of the

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... ecule is also computed. Vibrational energies are computed andcorrected for nonadiabatic effects-compared with experiment for several isotopes. It is argued on the basis of the remaining discrepancies that an improvement in the ab initio nonadiabatic corrections is necessary.