Tetragonal states of Fe and Mn have been studied by finding total energies at constant volume $V$ as a function of $c/a$ with the full-potential linearized-augmented-plane-wave method. Minima in $E_V\mathrm{}(c/a)\mathrm{}$ give the $c/a$ values of equilibrium states. Both Fe and Mn are shown to have stable and metastable equilibrium states in each of several magnetic phases. The calculations on Fe show an antiferromagnetic (AF) face-centered-tetragonal (fct) equilibrium state at $c/a=1.08,$ which has been stabilized as a strained epitaxial film. The calculations on Mn show an AF equilibrium state at $c/a=0.96\mathrm{}$ (fct), in agreement with the measured value of $c/a=0.95\mathrm{}$ on a crystal stabilized by alloying. Also AF bcc Mn is shown to be unstable, but an equilibrium AF state at $c/a=0.60\mathrm{}$ exists.

• Received 4 June 1999

DOI:https://doi.org/10.1103/PhysRevB.60.14533