# Photon-momentum transfer in diatomic molecules: an ab initio study

## TL;DR

This study investigates how two-center interference and molecular scattering phases influence photon momentum transfer to ionized electrons in diatomic molecules, using ab initio numerical solutions of the Schrödinger equation.

## Contribution

It provides a detailed ab initio analysis of photon momentum transfer in diatomic molecules, highlighting the roles of two-center interference and scattering phases across various configurations.

## Key findings

- Two-center interference affects momentum transfer at all internuclear distances.
- Deviations from classical models occur at low electron energies and small distances.
- Molecular scattering phase remains significant even at large internuclear distances.

## Abstract

For a molecule, the two-center interference and the molecular scattering phase of the electron are important for almost all the processes that may occur in a laser field. In this study, we investigate their effects in the transfer of linear photon momentum to the ionized electron by absorbing a single photon. The time-dependent Schr\"odinger equation of H$_2^+$ is numerically solved in {the multipolar} gauge in which the electric quadrupole term and the magnetic dipole term are explicitly expressed. This allows us to separate the contributions of the two terms in the momentum transfer. For different configurations of the molecular and the laser orientation, the transferred momentum to the electron is evaluated at different internuclear distances with various photon energies { and two-center interferences are identified in the whole region. At small electron energies and small internuclear distances, we find significant deviations from the prediction of the classical double-slit model due to the strong mediation of the Coulomb potential.} Finally, even for a large internuclear distance, our results show that a varying molecular scattering phase is important at all electron energies, which is beyond the simple prediction of the linear combination of the atomical orbitals.