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

Abstract.

Using the density functional theory (DFT) method, the geometrical structures of ${\rm In}_{m}X_{n}$ ($X={\rm Se}$, 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 ${\rm In}_{m}X_{n}$ clusters are found to be largely similar for $X={\rm Se}$ and Te, with the exception of ${\rm In}_{2}X_{3}$ . The energy gap exhibits the maximum for ${\rm In}_{2}{\rm Se}_{3}$ or ${\rm In}_{3}{\rm Te}_{2}$ . The electronic properties of ${\rm In}_{m}X_{n}$ clusters depend on their geometrical structures and, hence, on the value of m ; and ${\rm In}_{2}{\rm Se}_{3}$ shows a low vertical electron affinity (VEA) of about 1.60eV and a high vertical ionization potential (VIP) of about 9.33eV. The total magnetic moment is 1 or 0μ_B for the clusters with $m={\rm odd}$ (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 ${\rm In}_{m}X_{n}$ clusters exhibit similarity for $X={\rm Se}$ and Te with an exception of ${\rm In}_{2}X_{3}$. The energies of the strongest peaks of ${\rm In}_{m}{\rm Te}_{n}$ are largely smaller than the corresponding ${\rm In}_{m}{\rm Se}_{n}$ in both IR and Raman spectra. For UV-Vis spectra, the absorption peaks at 200-400nm for all clusters and 390–780 nm for m = 1 and 3 (except ${\rm In}_{3}{\rm Te}_{2}$ are likely to hint useful properties of UV and visible light absorption, respectively.