The equation of state for samarium chalcogenides is calculated at $T=0\mathrm{}$ in a model in which the promotion of an electron from $f$ level to $d$ band is accompanied by a lattice contraction so that the chemical potential of the $d$ electrons is reduced. With the nonlinearity in the lattice contraction as a function of $d$ band occupation taken as a variable parameter and using known spectroscopic and elastic data on samarium chalcogenides, an equation of state is calculated which agrees to within 20% with the experimental results.

• Received 23 January 1975

DOI:https://doi.org/10.1103/PhysRevB.11.4763