  Theoretical antiproton and proton cross sections for ionization and
excitation of hydrogen molecules as well as energy spectra of the ionized
electrons were calculated in the impact-energy range from 8 to 4000 keV. The
cross sections were computed with the close-coupling formulation of the
semi-classical impact-parameter method. The target was described using a
one-active electron model centered on the target and assuming a fixed
internuclear distance during the collision process. The dependence of the
ionization cross sections on the internuclear distance is examined. The present
cross sections are compared with experimental and theoretical data from the
literature. For impact energies E > 90 keV the obtained results for ionization
by antiproton impact are comparable to the experimental data while they
disagree for energies E < 80 keV.
