Self-consistent hand-structure calculations were performed for substituted
iron nitrides at several lattice parameters using the linear muffin-tin orb
ital method (LMTO) in the local spin density approximation. In particular,
four compounds were analyzed, namely Fe4N, PdFe3N, MnFe3N and SnFe3N. The c
alculations were performed in both ferromagnetic and non-magnetic states an
d the present results include total energy, equilibrium lattice parameter,
huh; modulus and critical pressure. From the results for the critical press
ure we conclude that the above compounds show Invar-like behavior. For smal
l total energy separation between ferromagnetic and non-magnetic states at
zero temperature. we performed free energy calculations including lattice a
nd electronic contributions to study the thermal expansion of the compound
employing a simple two level model. (C) 2000 Elsevier Science S.A. All righ
ts reserved.