Calculation of $p$–$v$ isotherms of iron with nickel and chromium and partial contributions of $s$, $d$ electron subsystems

The $p$–$v$ isotherms of iron, nickel, chromium, and the alloys Fe$_{0,7}$Cr$_{0,3}$ и Fe0,7Ni$_{0,3}$ are investigated theoretically on the basis of the Pettifor equations generalized to the case of magnetism. This approach pernits the analysis of anomalies in the isotherms associated with phase transition from body-centered cubic to close-packed structure, by isolating the partial contributions of s and d electron subsystems; the concept of collapsed structures is introduced. This method is applicable to a series of other metals and their alloys.