In this study, the pressure dependence of the optical properties of hexagonal close-packed, body-centered cubic and hexagonal phases of titanium was investigated using density functional theory. When Ti phases were compressed, the position of critical points such as equilibrium constants, static dielectric constants and also the main peaks in optical spectra shifted with an increase or decrease in energy compared to that at zero pressure. The imaginary dielectric function of all the phases under normal pressure and hydrostatic pressure was calculated. Under hydrostatic pressure, the optical conductivity of α phase increased, and the main peaks moved toward higher energies. Moreover, our results showed that the optical properties of α and ω phases change more than those of β phase. It was also demonstrated that the intensity of peaks of the energy loss function increased from α to β and decreased from β to ω. The optical reflectivity and absorption coefficient increased under pressure effects.
Optical properties of both linear and dimerized nanochains of titanium at different atomic distances are calculated using the full potential linearized augmented plane wave plus local orbital method, and using the generalized gradient approximation. When Ti nanochains were compressed, the position of critical points such as static dielectric constants and the main peaks in optical spectra shifted with an increased or decreased energy comparative to that at equilibrium constants. Under tensile strain ε1 max(ω) decreases in linear and dimerized structures. The plasma frequency for both structures decreases as the bond length increases. Moreover, the peaks of the energy loss function move toward higher energies with increasing bond length for linear structure, while they do not change significantly for the dimerized structure. The absorption for both nanostructures decreases by increasing the bond lengths.
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