Calculated structural-dependent optical properties of alloys TiNi, TiPd, and TiPt

Electronic structures and optical properties of martensitic alloys TiNi, TiPd, and TiPt in both the low-temperature B19 ${(B19\mathrm{}}^{\prime }$ in the case of TiNi) and the high-temperature B2 phases are systematically calculated using the flat-principles local density functional approach. Our results on TiNi B2 and B${19}^{\prime }$ phases agree well with the existing experimental data where drastic changes of optical conductivity in the infrared region from B2 to B${19}^{\prime }$ phase were observed. Our results show that optical matrix elements are important in understanding the optical properties of these alloys, especially in obtaining the correct peak intensities. Because of the different crystalline symmetry between the low-temperature B19 (B${19}^{\prime }$ in the case of TiNi) phase and the high-temperature B2 phase, different polarization dependence in the optical conductivity of the two phases is expected. We present the polarization-dependent optical conductivities in these martensitic alloys.