Ge_mC_n(m+n=7)团簇的密度泛函研究

Density functional study of Ge_mC_n(m+n=7) clusters

在密度泛函理论框架下,用广义梯度近似(GGA)的方法研究Ge_mC_n(m+n=7)团簇的基态几何结构,系统计算它们的基态束缚能B_e(au)、最高占据轨道(HOMO)与最低未占据轨道(LUMO)之间的能隙、二阶能量差分△_2E(au)以及团簇的总能量.研究表明,随掺杂C原子数的增加,Ge_mC_n(m+n=7)团簇的结构由三维空间转变为平面,再转变为线性结构;随着掺杂C原子数的增加,Ge_mC_n(m+n=7)团簇平均结合能逐渐增强,稳定性增加;Ge_mC_n(m+n=7)团簇的二阶差分能和能隙在Ge_5C_2和Ge_2C_5处出现峰值,说明这两种团簇较其它团簇具有较高的稳定性.

Based on the density functional theory within general gradient approximation （GGA）, we studied the geometry structures of the ground states of GemCn（m＋n=7） clusters and calculated the binding energies of ground states with the second-order energy difference △2E（au） and the total energies of clusters and energy gap on HOMO with LOMO. It is found that the geometry structures of GemCn（m＋n=7） clusters firstly change from space to plane with the increase in the number of carbons of cluster, then change from plane to line. Simultaneously, the average binding energy of GemCn（m＋n=7） clusters also becomes larger. The second-order energy difference shows the relative maximum at Ge5C2 and Ge2C5, meaning that the geometry structures of Ge5C2 and Ge2C5 are more stable than others.