Overbarrier model with electron backcapture

We present an extension of the classical overbarrier model [F. Sattin, Phys. Rev. A 62, 042711 (2000)] to include the effect of electron backcapture. Backcapture is the process by which an electron that has already been captured by the projectile ion is recaptured by the target atom. Backcapture reduces the electron capture cross section at low impact velocities when the projectile ionization energy is less than that of the target. This creates a cross-section peak. We alter the location of this peak to correspond to that predicted by an adiabatic criterion by using a free parameter of the model. These extensions bring the overbarrier model more in line with experimental data, especially at low impact velocity.