密度泛函理论研究H_2与Rh_n(n=1-8)团簇的相互作用
Density functional theory study of the interaction of H_2 with rhodium clusters
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摘要: 采用密度泛函理论对H_2与Rh_n(n=1-8)团簇的相互作用进行了系统研究.结果表明,Rh_n H_2体系的最低能量结构是在Rh_n团簇最低能量结构的基础上吸附H原子生长而成.吸附H原子没有改变Rh_n团簇的结构,键长是影响Rh_n和Rh_n H_2磁矩的主要因素.从优化后的几何结构可以看出吸附后的H_2发生断键,表明H_2分子发生了解离性吸附.当n≤5,H原子的吸附以桥位为主,当n≥6时,H原子开始出现空位吸附.H原子的吸附提高了Rh_n的稳定性和化学活性,较小的吸附能表明H原子易从Rh_n H_2中解离出来.二阶能量差分表明4是Rh_n H_2和Rh_n团簇的幻数.
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关键词:
- Rh_nH_2和Rh_n团簇 /
- 平衡结构 /
- 电子性质
Abstract: The adsorption for H atoms on the Rh_n cluster has been systematically investigated by density functional theory. The result indicates that the lowest energy structures of Rh_n H_2 are generated with H atoms being adsorbed on the lowest energy structure of Rh_n clusters, and the lowest energy structures of Rh_n clusters are not changed by adsorbing H atoms. The total magnetic moment is affected by average bond distance. The chemisorption of H atoms on Rh_n clusters belongs to dissociative adsorption. When H_2 is absorbed on the Rh_n clusters, the stability and chemical action of corresponding clusters are dramatically increased. The second order difference indicates 4 is magic number in Rh_n H_2 and Rh_n clusters. Among various possible adsorption sites, bridge site is energetically preferred for n≤5. The hollow site adsorption appears for n≥6. -
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