铋纳米管电子性质的第一原理研究

运用第一原理分子动力学方法系统研究了铋纳米管的稳定性和电子性质 .发现铋纳米管的应变能 (StrainEnergy)符合经典的 1/R2 规律 .铋纳米管的能隙在 0 .7— 0 .8eV左右 ,具有半导体的特性. A first principle molecular dynamics with density functional theory and ultra-soft pseudopotential has been performed on the bismuth nanotubes. The strain energies are found to follow the classical 1/R 2 strain law. The bismuth nanotubes are expected as semi-conductor with the band gaps around 0.7 - 0.8 eV.     

金属键优选方案：钠团簇基态构形

根据钠团簇金属键的特点，结合第一原理分子动力学模拟，提出了一种“金属键优选方案”. 系统地研究了团簇Na_n (n≤15)的基态构形，亚稳构形和团簇从小到大演化的规律. 在较大钠团簇(13≤n≤15)的表面上，存在着类似平面的子结构，这些子结构与钠bcc晶体的最大面密度(110)面有关. 根据钠团簇演化的规律，可理解正二十面体特大钠团簇(1500<n<22000)形成的可能途径.     

Optimum metallic-bond scheme: Theoretical study of geometric structures for ground-state sodium clusters

We present an optimum metallic-bond scheme to study the geometric structures of sodium clusters Na_n(n⩽15) systematically by combining the characteristics of metallic bonds and the first principle molecular dynamics simulation. The scheme provides an optimum way to examine almost all stable structures of sodium clusters and to determine their ground state structures. It is interesting to note that for the larger sodium clusters (13⩽n⩽15), there are some plane-like substructures on their surfaces, which resemble the fragments of the (110) plane with the highest atomic area density in the bulk bcc sodium crystal. We also propose a possible way to understand the formation of large icosahedral sodium clusters (1500<n<22000).     

Novel Bismuth Nanotubes

Theoretical investigations show that bismuth nanotubes are semiconductors for all diameters,For small diameter bismuth nanotubes,the band structures and bandgaps vary strongly with the strong hybridization effect.When the diameters are larger than 18A,the bandgaps of Bi(n,n) and (n,0) nanotubes approach 0.63eV,corresponding to the bandgap of bismuth sheet at the T point,Thus,bismuth nanotubes are expected to be a potential semiconductor nanomaterial in future nanoelectronics.     

HCP分子异构化过程的电子基态势能面:对密度泛函理论计算的检验

密度泛函理论提供了一种能处理较大团簇体系且计算量合适的方法. 采用密度泛函近似方法计算得到HCP分子势能面. HCP的基态势能面涉及其整个异构化过程. 将密度泛函计算的势能面与“精确”的势能面（根据实验振动谱拟合的势能面和计算量巨大的高精度量化计算的势能面）进行了比较. 结果表明,密度泛函计算HCP势能面的精度在0.1 eV以内.