Lattice dynamics and phase transition of NiTi alloy

We have performed detailed first-principles calculations to investigate the structural and lattice dynamical properties of NiTi alloy. The calculated static structures consist well with the experimental data and other theoretical results. With quasi harmonic approximation, the phase boundary between B19′ and BCO phases can be described as a five order polynomial T = 100 − 89.28 P + 296.75 P 2 − 717.94 P 3 + 734.62 P 4 − 274.25 P 5 . The change of vibrational entropy is 0.07 k B /atom at the transition temperature 100 K under zero pressure.