研究目的
To determine the lowest-energy structures of large GeN clusters (N = 45–70) using a two-step unbiased global search and to analyze their atomic structures and electronic properties.
研究成果
The most stable structures for large GeN clusters (N=45-70) are stuffed cages, similar to silicon clusters. Structural transition to spherical-like shapes occurs around N=70, and electronic properties (binding energy, ionization potential, HOMO-LUMO gap) show good agreement with experiments, gradually approaching bulk values with increasing size.
研究不足
The study cannot guarantee the true global minima on the potential energy surface with DFT accuracy, and the computational methods may have inherent approximations. The results are based on theoretical simulations and may not fully capture experimental complexities.
1：Experimental Design and Method Selection:
A two-step optimization strategy was employed, involving genetic algorithm (GA) combined with non-orthogonal tight-binding (NTB) method for initial global search, followed by basin-hopping (BH) search coupled with density functional theory (DFT) for refinement.
2：Sample Selection and Data Sources:
GeN clusters with N = 45, 50, 55, 60, 65, 70 atoms were selected as representatives.
3：List of Experimental Equipment and Materials:
Computational methods and software were used; no physical equipment mentioned.
4：Experimental Procedures and Operational Workflow:
For each cluster size, GA iterations (20,000) were performed with NTB, then BH iterations (over 10,000) with DFT local optimization. DFT calculations used PBE functional and DND basis set in DMol3 package.
5：Data Analysis Methods:
Vibrational frequencies were calculated to ensure minima; binding energy, ionization potential, HOMO-LUMO gap, and coordination numbers were analyzed.
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