General equations of motion are introduced for the evaluation bf spin
dynamics in magnetic materials. The theory uses the adiabatic separati
on oi diagonal and off-diagonal components of the spin density matrix:
This adiabatic approach considers the orientation of the local magnet
ic moments to be slowly varying relative to, their magnitudes. The ang
les of the magnetization density are introduced as collective variable
s in density functional theory. The equations and technique can be sim
ultaneously combined with those of first-principles molecular dynamics
for the consistent treatment of spin-lattice interactions. Stochastic
and deterministic approaches for treating finite temperature effects
are introduced for such dynamics. The method is implemented within the
local density approximation and applied to gamma-Fe, a frustrated sys
tem where we obtain additional low-energy magnetic configurations.