The phase diagram and electronic structure of Pd-V alloys: ab initio density functional calculations

A parameter-free approach based on ab initio density functional calculations is shown to describe the phase stability and order-disorder transformations in Pd-V substitutional alloys and intermetallic compounds with remarkable accuracy, allowing first-principles calculations of the complete alloy phase diagram. The investigations are based on electronic structure and total-energy calculations for ordered compounds and disordered alloys (treated in a supercell approximation) using gradient-corrected exchange-correlation functionals and a plane-wave-based all-electron method. All calculations involve a complete optimization of all structural degrees of freedom. The calculation of the free energies of the competing phases is based on rather simple mean-field descriptions of long- and short-range-ordering phenomena, using concentration-dependent interchange and shell interaction parameters. In addition, the electronic structures of ordered compounds and of substitutional alloys have been analysed.