Adiabatic dynamics of local spin moments in itinerant magnets

Using the adiabatic approximation, we derive the equations of motion for lo cal spin moments which are valid for itinerant as well as tight-binding spi ns. Material parameters in the equations of motion can be obtained using st andard density functional methods, because they depend only on the energy a nd Berry phase of the constrained ground state of frozen spin configuration s. For the calculation of spin waves in a collinear magnet, ii. is sufficie nt to know the quadratic forms of total energy and spin component along the symmetry axis as functions of the spin deviations from the ground state co nfiguration.