中文摘要：

在密度泛函理论基础上，优化不同金电极距离下以羧基为末端基团的硫醇分子的几何结构，得到了体系能量与金电极距离的变化关系。根据外力与能量的关系式，计算了不同金电极距离下对应的压力值。利用弹性散射格林函数方法计算了不同压力下分子结的伏安曲线。研究结果表明，当两个金电极距离被拉伸为2．08nm时，羧基断开了与金电极的物理接触。随着外加压力的增加，分子结的电导值快速地增加。

英文摘要：

Based on the density functional theory, the geometric structures of extended molecules are optimized, and the relationship between the total energy of the system and the electrode＇ s distance is obtained. With the formula of force and energy, the external pressure at different electrode＇ s distance is calculated. The current - voltage curves at different pressure are calculated using the elastic scattering Green function theory. When the distance between the two gold electrodes is about 2.08 nm, the physical contact between the carboxyl and the electrode is broken. The numerical results show that in a suitable pressure region, the conductance inereases rapidly with the increase of the pressure between the two electrodes.