Two-effective center approximation for the single ionization of molecular hydrogen by fast electron impact

The triple differential cross section (3DCS) for the $(e,2e)$ ionization of diatomic hydrogen is determined using the first-order transition matrix element of the Born series. A two-effective center continuum wave function which takes into account the diatomic character of the target is introduced to describe the ejected electron in the exit channel. Vertical transitions from the equilibrium position of the ¹Σg⁺ ground electronic state of the target to the ²Σg⁺ ground electronic state of the residual H₂⁺ are considered for relatively high incident electron energy values ({~}4 keV). This approach, which needs relatively small computational efforts to apply it to other diatomic systems, produces results that are in good agreement with existing experimental data. The influence on 3DCS of the screening of the nuclear charges produced by the residual bound electron in the exit channel is studied.