排序方式: 共有42条查询结果,搜索用时 718 毫秒
1.
2.
Structural behaviors of silicon and germanium clusters under the recently proposed modified Stillinger-Weber (SW) potential have been studied by molecular dynamics method along with the con-jugate-gradient optimization. Since the SW potentials have been derived from the properties of bulk materials, it gives relatively large discrepancy when the cluster number is small, e.g. n=3 and 4. When n>4, the ground-state structures under the modified SW potential are close to that from the first-principle calculation. The binding energies are also improved under the modified SW potential. These results may be attributed to the relative enhancement of the two-body term over the three-body term in the modified SW potential, which leads to structures with a preferential coordination number 4. Structural behaviors of germanium clusters are similar to those of silicon. 相似文献
3.
4.
5.
6.
A theoretical model for describing H2 dissociative chemisorption on Cu surfaces is proposed. The sticking probability S is calculated as a function of vibrational state, average kinetic energy and incident angle of hydrogen molecular beam. Within the theoretical frame of this model, the different contributions to S from H2(v = 0) and H2(v = 1) can be clearly distinguished. The calculated results indicate that vibrational energy significantly promotes the chemisorption of H2 on Cu surfaces in the region of low translational energy. The equations derived can be used to analyze the experimental data for both pure and seeded molecular beams. 相似文献
7.
Band structures of Si-C and Si-C-Ge alloys are calculated by using the ab initio LMTO (linear muffin-tin orbital) method within the framework of atomic-sphere approximation. The effects of different atomic configuration and lattice relaxation on the band structure of alloys are taken into account. The results show that for large concentrations of C in Si and Si-Ge, the band gap increases monotonically, while for small concentrations of C in Si and Si-Ge, the band gap shrinks. The lattice relaxation further reduces the band gap. The possible explanations for the reduction of band gap of Si-C and Si-C-Ge alloya are presented. 相似文献
8.
采用离散变分Xα方法分别计算了CO和NO以C(或N)端顶位吸附在CuO(110)及Cu2O(110)表面上的基态势能曲线,结果表明:CO在Cu2O表面上的吸附强,而在CuO表面上的吸附弱;NO则在CuO表面上吸附强,在Cu2O表面上吸附弱.它们的吸附能的大小顺序为:CuO-NO>Cu2O-CO>Cu2O-NO>CuO-CO.对于CuO-NO(或CO)吸附体系,主要是Cu的3d轨道与吸附分子的2π轨道间的相互作用;对于Cu2O-CO(或NO)吸附体系,则主要是吸附质分子的5σ及2π分子轨道与其顶位Cu1的4s及4p轨道和侧位Cu2的3d轨道相互作用.本文通过吸附势能曲线、态密度分析、成键分析及电荷转移量和方向等方面对实验现象做了合理的解释. 相似文献
9.
10.
本文研究GaAs(110)面旋转弛豫的电子结构,采用一个原子集团来模拟GaAs(110)面,在其内边界上用一些“类Ga”和“类As”原子来钝化伸向体内的悬挂键,以消除由于有限模型而引起的多余边界效应。用EHT方法计算集团的总能量,由能量极小定出GaAs(110)面最稳定的弛豫位置为表面旋转角ω=18°,表面Ga原子向体内下降0.33?,As原子上升0.13?,这与Pandey等人从光电子部分产额谱所得的结果基本一致。本文还计算了理想和弛豫的GaAs(110)面的态密度,发现对于理想的(110)面禁带中确实存在一个空的表面峰。弛豫后,该峰向上移动进入导带,禁带中不再出现表面峰,与实验结果相符。
关键词: 相似文献