The single-center adiabatic-nuclei convergent close-coupling method is used to investigate positron collisions with molecular hydrogen (${\mathrm{H}}_2$) in the ground and first vibrationally excited states. Cross sections are presented over the energy range from 1 to 1000 eV for elastic scattering, vibrational excitation, total ionization, and the grand total cross section. The present adiabatic-nuclei positron-${\mathrm{H}}_2$ scattering length is calculated as $A=-2.70a_0$ for the ground state and $A=-3.16a_0$ for the first vibrationally excited state. The present elastic differential cross sections are also used to “correct” the low-energy grand total cross-section measurements of the Trento group [A. Zecca et al., Phys. Rev. A 80, 032702 (2009)] for the forward-angle-scattering effect. In general, the comparison with experiment is good. By performing convergence studies, we estimate that our $R_m=1.448a_0$ fixed-nuclei results are converged to within $\pm 5\%$ for the major scattering integrated cross sections.

• Received 14 November 2016

DOI:https://doi.org/10.1103/PhysRevA.95.022707