二十面体对称性(I_h)分子的从头计算研究 Ⅱ.铜原子簇Cu_(13)的电子结构  

Ab initio Studies on Icosahedral Molecules Ⅱ. The Electronic Structure of Cu_(13)

作　　者：张明瑜[1] 于微舟[1] 李晓天[1] 江元生[1] 

机构地区：[1]吉林大学理论化学研究所,长春130021

出　　处：《化学学报》1991年第2期105-112,共8页Acta Chimica Sinica

基　　金：国家自然科学基金

摘　　要：应用对称性约化计算方案,完成了铜原子簇Cu_(13)(I_h)三种基组下的从头计算,最大维数390.为了进行比较,也进行了Cu_2、Cu_4、Cu_6及Cu_8的计算.经过优化,获得基态及平衡几何、布居、结合能等数据,表明Cu_(13)可能稳定存在.Cu_(13)中以d成分为主的分子轨道均已填满,对化学键无实际贡献,成键作用为s,p性质;再者,d带与s带不相交叠,无金属Cu能带的特征.无论平衡几何、布居及结合能数值均与采用的基组很有关系,虽然定性趋势是一致的.A series of ab initio calculations on copper clusters Cu_n with n equal to 2, 4, 6, 8 and 13 was performed where icosahedral Cu_(13) is specifically emphasized. Three different contracted Gaussian sets used by Basch, Roos improved further with additional polarized, p-, d-functions are adopted, namely Ⅰ Ⅱ Ⅲ (15s9p5d)——(6s4p2d) (12s7p5d)——(5s3p2d) (15s10p6d)——(5s4p2d) They give identical ground state for CU_(13) on optimization, i.e. ~6A_g (core)^(234)(3d)^(130)(10a_g)~2(12t_(1u)~6(12h_g)~5 The optimized distance between the central and the peripheral atom, the orbital energies and the populations are listed in Table 2 respectively for three basis sets. They show some similarities that s-orbitals are much more wide-spread without overlapping the narrow d-band as indicated in Fig. 3. This phenomenon differs from metal bulk of Cu where d-bands are covered by s-bands. In other words, Cu_(13) does not exhibit the main feature of the band structures in agreement with the conclusio(?) given by Demuynck. The binding energies per atom calculated, being Ⅰ 65.52kJ/mol; Ⅱ 153.78kJ/mol; Ⅲ 230.82kJ/mol, signify the stability of Cu_(13) and the total populations of s, p and d orbitals reveal that electrons transferring from s, d orbitals into empty p orbitals. Nevertheless, the role of 4s orbitals is determinate for binding. The smaller clusters Cu_2, Cu_4, Cu_6 and Cu_8 are calculated by adopting basis set Ⅲ. Geometry symmetries, optimized bond distanoes, total energies (in a.u.) and binding energies per atom (in kJ/mol) are displayed in Table 5. It is of interest to note that both the bond lengths and binding energies are increased in proportion to the cluster size, in agreement with the suggestion given by Bachmann. On the other hand, the separation between d and s bands is diminished as the cluster size is increased. as shown in Fig. 4. In order to illustrate the discrepancy between the ab initio and X_α calculations on Cu_(13), additional calculations for various bond distances les

关 键 词：多面体 对称性 分子 从头计算 In 

分 类 号：O643.322[理学—物理化学]