First-principles thermodynamics of transition metals and alloys: W, NiAl, PdTi

摘要

We apply the pseudopotential density functional perturbation theory approachalong with the quasiharmonic approximation to calculate the thermal expansionof tungsten and two important metallic alloys, NiAl and PdTi. We derive thetheory for anisotropic crystal structures and test the approximation that theanisotropic effects of thermal expansion are equivalent to negative pressure -this simplifies the calculation enormously for complex structures. Throughout,we find excellent agreement with experimental results.