  We compute the electric spin susceptibility of Bloch electrons with
spin-orbit coupling to second order. We find that it is possible to generate a
nonequilibrium spin polarization in the bulk of non-magnetic
inversion-symmetric materials using linearly polarized electric fields, but the
process depends on interband coherence and produces heating. It may be possible
to avoid heating with circular polarization in certain scenarios. The standard
Edelstein effect and spin orientation effects are recovered in appropriate
limits within the formalism. Finally, the electric spin susceptibility of
metals has contributions proportional to spin multipole moments of the Fermi
sea that dominate the low frequency spin response.
