Bethe logarithm for the hydrogen molecular ion H2+

The mean excitation energy (the Bethe logarithm) is calculated for the lowest rotational (up to L=4) and vibrational (up to v=4) states of the hydrogen molecular ion H-2(+). The calculations are based on a method of the direct integration over photon momenta. The estimated accuracy of obtained values is about 10(-6). The Araki-Sacher Q term is computed as well, which allows us to evaluate the leading order alpha(3) radiative correction to the rovibrational energies of the hydrogen molecular ion.