Band Structures of Noncollinear Magnets in Gamma-Mn and Gamma-Fe

Local spin density functional theory is applied within the linearized muffin-tin orbital atomic sphere approximation (LMTO ASA) method to calculate the electronic structures of non-collinear antiferromagnets in FCC manganese and iron. Direct application of the theory leads to a Hamiltonian which is doubly degenerate for every band at every k-point. An irreducible representation is found which overcomes this problem. The total energies of single, double and triple spin density wave structures are found to be essentially indistinguishable within the limits of the calculation.