Photoionization from the ground and excited vibrational states of H$_{2}^{+}$

Photoionization cross sections for all bound vibrational levels of the 1s$\sigma_{\text{g}}$ state of H${}_{2}^{+}$ are presented. The only approximation employed in our calculation of vibrationally-resolved photoionization cross sections is the Born-Oppenheimer approximation. The origin of the near threshold oscillations in the vibrationally-resolved photoionization cross sections is described. A benchmark set of photoionization cross sections are presented. Fixed-nuclei photoionization cross sections are calculated using true continuum wave functions for H${}_{2}^{+}$ at an internuclear separation of 2 a${}_{0}$ and compared with previous calculations with excellent agreement found in many cases, but not all.