The shear modulus of neutron star matter in the free-neutron state

The lattice whose properties have been tabulated by Baym et al. (1971) is unstable against nuclear quadrupole deformation for nuclear charge Z>Zsub(c), 120<Zsub(c)<201, if the electron gas is assumed to be of uniform density. Electron screening corrections to the change in energy density with nuclear deformation are large and it is shown that their inclusion removes the instability. The expression of Fuchs (1936) given originally for monovalent metals, overestimates the shear modulus of the lattice, for large Z, by less than a factor of two. (Auth.)