Positron scattering and annihilation from the hydrogen molecule at zero energy

TL;DR

This paper uses a variational approach to study positron scattering and annihilation on hydrogen molecules at zero energy, revealing rapid variations in scattering parameters linked to virtual state formation.

Contribution

It introduces a correlated Gaussian basis for accurate wave function modeling in positron-H2 scattering, providing new insights into scattering length and annihilation rates at zero energy.

Findings

Scattering length approximately -2.7 a0

Zero energy Z_eff of 15.7 matches experimental data

Rapid variation of scattering parameters near R ≈ 3.4 a0

Abstract

The confined variational method is used to generate a basis of correlated gaussians to describe the interaction region wave function for positron scattering from the H$_2$ molecule. The scattering length was $\approx -2.7$ $a_0$ while the zero energy $Z_{\rm eff}$ of 15.7 is compatible with experimental values. The variation of the scattering length and $Z_{\rm eff}$ with inter-nuclear distance was surprisingly rapid due to virtual state formation at $R \approx 3.4$ $a_0$.