  The strong magnetic fields found on the surface of magnetars are known to
have profound effects in the physics of atoms in magnetar envelopes. We argue
that the Friedel oscillations in the Coulomb force between the ions due to
electron shielding can, for certain values of the parameters, be the dominant
effect determining the crystal structure in the outer crust of magnetars. We
estimate the densities and magnetic fields for which this occurs, compute some
of the elastic moduli and lattice phonon dispersion relations in this "Friedel
crystal" phase.

High Energy Astrophysical Phenomena;Nuclear Theory