A DFT study of Se Te clusters.

Area of Science:

• Materials Science
• Computational Chemistry
• Condensed Matter Physics

Background:

• Selenium-Tellurium (Se-Te) glasses are technologically important amorphous materials.
• Understanding the fundamental properties of small clusters can provide insights into bulk glassy systems.
• Previous studies have explored Se-Te glasses, but the role of small clusters remains an active area of research.

Purpose of the Study:

• To investigate the characteristic properties of small Se-Te clusters (n=5-10) using first-principles calculations.
• To establish the relationship between the properties of these small clusters and bulk Se-Te glassy systems.
• To analyze the structural, bonding, vibrational, and electronic properties of Se-Te clusters.

Main Methods:

• Employed first-principles calculations, including genetic algorithm-based structure prediction (USPEX) and energy minimization (VASP).
• Calculated structural properties, Raman and IR spectra, and electronic band structure (HOMO-LUMO levels).
• Computed dielectric functions, energy loss spectra, and absorption coefficients.

Main Results:

• Identified buckled ring-like structures as the lowest energy configurations, stabilized by Se-Te heteropolar bonds.
• Raman and IR spectra confirm the dominance of Se-Te heteropolar bonds, consistent with experimental data on Se-Te glasses.
• Observed low-frequency vibrational modes characteristic of amorphous materials and identified π-plasmons in the UV-visible region.

Conclusions:

• Small Se-Te clusters exhibit properties analogous to bulk Se-Te glassy systems.
• The bonding mechanisms and electronic structures of these clusters provide a foundation for understanding amorphous Se-Te materials.
• These findings highlight the significant role of small clusters in the formation and properties of glassy Se-Te systems.