First-principles study of InmXn (X = Se, Te; m + n=5) clusters: Structural, electronic, magnetic and spectral properties

Using the density functional theory (DFT) method, the geometrical structures of InmXn (X = Se, Te; m + n = 5) clusters are optimized, and their relative stability as well as electronic, magnetic and spectral properties are calculated. The ground state structures of InmXn clusters are found to be largely similar for X = Se and Te, with the exception of In2X3. The energy gap exhibits the maximum for In2Se3 or In3Te2. The electronic properties of InmXn clusters depend on their geometrical structures and, hence, on the value of m; and In2Se3 shows a low vertical electron affinity (VEA) of about 1.60 eV and a high vertical ionization potential (VIP) of about 9.33 eV. The total magnetic moment is 1 or 0 mu B for the clusters with m = odd (1, 3) or even (2, 4), respectively. The local magnetic moments of X atoms amount to about 99.9% of the total magnetic moment, while those of In atoms are merely 0.1%. The IR and Raman spectra of InmXn clusters exhibit similarity for X = Se and Te with an exception of In2X3. The energies of the strongest peaks of InmTen are largely smaller than the corresponding InmSen in both IR and Raman spectra. For UV-Vis spectra, the absorption peaks at 200-400nm for all clusters and 390-780nm for m = 1 and 3 (except In3Te2) are likely to hint useful properties of UV and visible light absorption, respectively.