Constrained density functional theory for first principles spin dynamics

Constrained density functional theory is used to formulate a theory of gene ral noncollinear spin systems which makes it possible to implement first pr inciples spin dynamics in a manner that is firmly grounded in density funct ional theory. At each time step, local constraining fields are calculated f rom a self-consistent algorithm. In addition to discussing the conceptual b asis of the resulting constrained local moment model we illustrate the theo ry by explicit calculations for the relative rotation of the corner and bod y center moments of bcc iron. (C) 1999 American Institute of Physics. [S002 1-8979(99)58508-3].