Temperature influence on a molecular switching under electric field: quantum transport ab initio calculation*

A molecular transistor based on torsion-angle conformation change driven by gate electric field is designed and studied using {\it ab initio} calculations. This transistor consists of a ${\rm SH-C_6H_2F(CH_3)C_6H_2(CH_3)F-SH}$ molecule sandwiched between two Au(111) electrodes, where the interaction between the molecular dipole and a gate voltage induced electric field will cause the molecule to twist along its c-axis. This twist changes the quantum conductivity of the molecule. The effect of thermal fluctuation on the molecular conformation is studied, so is the ability of the transistor to shut off its current. The advantages and challenges of using such molecular conformation change as a mechanism for transistor gating are discussed