Use of single-body potentials to accurately describe virtual positronium formation in positron collisions

We present a single-body adiabatic potential to investigate the role of virtual positronium (Ps) formation in positron scattering with atoms at energies below the Ps formation threshold. Our model is applied to positron scattering by hydrogen and noble-gas atoms. The potential is decomposed into two components: the correlation-polarization (CP) potential, derived from perturbation theory for the positron-hydrogen system and generalized for other atoms, and the virtual positronium (VPs) potential. The VPs potential is modeled as a short-ranged attractive term based on the CP component but shifted toward the atom's vicinity, with its strength controlled by a semiempirical parameter fine tuned to match the scattering length to reference values. Our results show that the inclusion of the VPs term is essential for reproducing experimental measurements and results from other theoretical models for both integrated and differential cross sections.