First-principles calculations of the specific-heat mass enhancements in ${\mathrm{UIr}}_3$, ${\mathrm{UPt}}_3$, and ${\mathrm{UAu}}_3$

By including dynamic fluctuations around the local-density-approximation (LDA) electronic structure we find good agreement for the specific-heat mass-enhancement factors for U${\mathit{X}}_3$ (X=Ir, Pt, Au). The fluctuations, which are calculated through to second-order in the perturbation, are restricted to those caused by strong, local, uranium 5f electron-electron interactions, for which the calculated effective interaction strength is 2 eV. The strong material dependence of the second-order mass-enhancement factors is related to the composition dependence of the Fermi energy and the underlying one-electron LDA density of states.