Thermochemical Parameters and Growth Mechanism of the Boron-Doped Silicon Clusters, SinBq with n = 1鈥?0 and q = 鈭?, 0, +1

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• 作者：Nguyen Minh Tam ; Truong Ba Tai ; Minh Tho Nguyen
• 刊名：The Journal of Physical Chemistry C
• 出版年：2012
• 出版时间：September 20, 2012
• 年：2012
• 卷：116
• 期：37
• 页码：20086-20098
• 全文大小：794K
• 年卷期：v.116,no.37(September 20, 2012)
• ISSN：1932-7455

文摘

A systematic investigation of the boron-doped silicon clusters Si_nB with n ranging from 1 to 10 in the neutral, anionic, and cationic states is performed using quantum chemical calculations. Lowest-energy minima of the clusters considered are identified on the basis of the B3LYP, G4, and CCSD(T) energies. Total atomization energies and thermochemical properties such as ionization energy, electron affinity, and dissociation energies are obtained using the high accuracy G4 (B3LYP-MP4-CCSD(T)) and CCSD(T)/CBS (complete basis set up to n = 4) methods. Theoretical heats of formation are close to each other and used to assess the available experimental values. The growth mechanism for boron-doped silicon clusters Si_nB with n = 1鈥?0 emerges as follows: (i) each Si_nB cluster is formed by adding one excess Si-atom into the smaller sized Si_n鈥?B, rather than by adding B into Si_n, (ii) a competition between the exposed (exohedral) and enclosed (endohedral) structures occurs at the size Si₈B where both structures become close in energy, and (iii) the larger size clusters Si₉B and Si₁₀B exhibit endohedral structures where the B-impurity is located at the center of the corresponding Si_n cages. The species Si₉B^{鈥?/sup>, Si₉B, and Si₁₀B+ are identified as enhanced stability systems with larger average binding energies and embedded energies. The higher stability of the closed shells Si₉B鈥?/sup> and Si₁₀B+ can be rationalized in terms of the jellium electron shell model and spherical aromaticity.}