  Neutron star surfaces and atmospheres are unique environments that sustain
the largest-known magnetic fields in the universe. Our knowledge of neutron
star material properties, including the composition and equation of state,
remains highly unconstrained. Electron-atom collisions are integral to
theoretical thermal conduction and spectral emission models that describe
neutron star surfaces. The theory of scattering in magnetic fields was
developed in the 1970s, but focused only on bare nuclei scattering. In this
work, we present a quantum treatment of atom-electron collisions in magnetic
fields; of significant importance is the inclusion of Pauli repulsion arising
from two interacting electrons. We find strange behaviors not seen in
collisions without a magnetic field. In high magnetic fields, Pauli repulsion
can lead to orders of magnitude enhancements of collision cross sections.
Additionally, the elastic collision cross sections that involve the ground
state become comparable to those involving excited states, and states with
large orbits have the largest contribution to the collisions. We anticipate
significant changes to transport properties and spectral line broadening in
neutron star surfaces and atmospheres, which will aid in spectral diagnostics
of these extreme environments.
