TY  - EJOU
AU  - Han, Xuecai 
AU  - Tong, Yilin 
AU  - Bao, Jiaqi 
AU  - Yu, Kan 

TI  - <i>Ab</i> <i>initio</i> Investigation of Structural Units and Raman Vibrational Characteristics in Ge-Se-Te Glasses
T2  - Chalcogenide Letters

PY  - 2026
VL  - 23
IS  - 1
SN  - 1584-8663

AB  - Chalcogenide glasses in the Ge-Se-Te system possess wide infrared transparency and strong optical nonlinearity, yet the microscopic origin of their vibrational behavior remains unclear. Using <i>ab initio</i> calculations, we analyzed Raman-active modes in GeSe<sub>x</sub>Te<sub>4−x</sub> (x = 0–4) tetrahedra, edge-sharing tetrahedra, and ethane-like Ge<sub>2</sub>Se<sub>2x</sub>Te<sub>6−2x</sub> (x = 0–3) clusters. For GeSe<sub>x</sub>Te<sub>4−x</sub> (x = 0–4) tetrahedra, the symmetric stretching vibrations exhibit two families: Ge-Se-dominated and Ge-Te-dominated modes, both showing monotonic redshifts as the number of same-type bonds increases. In edge-sharing tetrahedra, the Ge-Ch-Ge-Ch (Ch = Se or Te) four-membered-ring breathing frequency decreases with higher Te content, and a comparable softening is observed in the A<sub>1g</sub> and E<sub>g</sub> modes of ethane-like Ge<sub>2</sub>Se<sub>2x</sub>Te<sub>6−2x</sub> units, where Te substitution lowers the breathing and antisymmetric stretching frequencies. These systematic redshifts are well explained by harmonic vibrational theory and bond polarizability models, indicating that Te substitution increases effective mass, softens local force constants, and redistributes bond-polarizability contributions, collectively leading to weaker Ge–Ch bonding and reduced structural rigidity. The results provide microscopic insight into the compositional evolution of Raman features in Ge-Se-Te chalcogenide glasses.
KW  - Ge-Se-Te system; <i>ab initio</i> calculation; Raman vibrational mode

DO  - 10.32604/cl.2026.075604