Molecular dynamics method to itinerant magnets with complex magnetic structure

A molecular dynamics method which allows us to determine the magnetic structures of itinerant magnets with a few hundred atoms in a unit cell has been developed on the basis of the functional integral method. The method yields the generalized Hartree-Fock approximation at the ground state, and describes the finite temperature magnetism accompanied by the second order phase transition. The results for fee transition metals with the use of 108 atoms in a unit cell show a complex antiferromagnetic (AF) structure for the d electron number n(d)=6.0, the first-kind AF for n(d)=6.2, the helical structure with Q=(0,1/3,1)2 pi/a for n(d)=6.4, the helical structure with the same Q but with modulated amplitudes of local moments for n(d)=6.6. A helical structure with Q=(0,1/3,2/3)2 pi/a is obtained for gamma-Fe. (C) 1997 American Institute of Physics.