C_(20)与Si(100)-(2×1)重构表面相互作用的计算机模拟研究

COMPUTER SIMULATIONS OF THE INTERACTIONS BETWEEN C_(20) AND A RECONSTRUCTED SILICON (100)-(2×1) SURFACE

用分子动力学的方法模拟研究了低能C2 0 与Si( 10 0 ) ( 2× 1)重构表面的相互作用过程。将描述C、Si结构的Tersoff势和描述原子间短程排斥的KrC势相结合 ,建立了一个混合势作为原子间的相互作用模型。荷能C2 0 垂直轰击到Si( 10 0 ) ( 2× 1)表面后 ,由于在〈110〉方向受到非对称力场的作用而产生横向的集体运动 ,改变的入射能量导致C2 0 与Si( 10 0 ) ( 2× 1)表面最接近的垂直距离不同 ,从而受到不同的横向力场的作用而产生不同的表面运动特性。C2 0 能量耗尽后稳定吸附在Si( 10 0 ) ( 2× 1)表面 ,且只有两个稳定吸附位置 ,即二聚体 (dimer)和“峡谷”(trough)位 ,这两个吸附位置的存在可用C2 0 与Si( 10 0 ) ( 2× 1)表面之间非对称的表面力场分布来定性解释。最终C2 0与Si( 10 0 ) ( 2× 1)表面有强烈的化学键形成。

The interaction between a low energy C 20 molecule and a reconstructed silicon (100)-(2×1) surface is simulated with a hybrid potential, which is a combination of the Tersoff potential and the repulsive KrC potential. After impacting of the silicon substrate, the C 20 cluster is found to move along 〈110〉 direction as a rigid sphere. The collective motion of the C 20 molecule can be explained by the anisotropic force field between the dimerized silicon surface and the C 20 molecule. Different impact energies lead to different closet interaction distances between the C 20 molecule and the silicon surface, which generate different distributions of the lateral force field. Changes in the force field lead to different kinetic behavior of the C 20 along the 〈110〉 direction. Finally, the C 20 comes to rest on the surface when its kinetic energy is consumed up. In the trough or on the top of a dimer are the two energy favored adsorption sites of the C 20 on the silicon surface. The formation of C Si bonds is an indication that strong bindings between the C 20 and the silicon surface exist. These results are consistent with experimental findings of C 20 molecules adsorbed on a reconstructed silicon surface. [