Tetragonal Equilibrium States of Iron

First-principles total-energy calculations on tetragonal equilibrium states with c/a>1, the fcc value. The bulk layers of an epitaxial film on Fe on Cu(001), which are almost fcc with the Cu lattice constant, are shown to be stable in the antiferromagnetic phase, but inherently unstable in the ferromagnetic phase. The structure of tetragonal equilibrium antiferromagnetic Fe is estimated to be a = 3.47Å, c = 3.75Å.