  Analytical gradients of the total energy are provided for local density and
generalized-gradient hybrid approximations to generalized Kohn-Sham
spin-current density functional theory (SCDFT). It is shown that gradients may
be determined analytically, in a two-component framework, including spin-orbit
coupling (SOC), with high accuracy. We demonstrate that renormalization of the
electron-electron potential by SOC-induced spin-currents can account for
considerable modification of crystal structures. In the case of Iodine-based
molecular crystals, the effect may amount to more than half of the total
modification of the structure by SOC. Such effects necessitate an SCDFT, rather
than DFT, formulation, in which exchange-correlation functionals are endowed
with an explicit dependence on spin-current densities. An implementation is
presented in the \textsc{Crystal} program.
