Sergueev N, Roubtsov D, Guo Hong
Center for the Physics of Materials and Department of Physics, McGill University, Montreal, PQ, Canada, H3A 2T8.
Phys Rev Lett. 2005 Sep 30;95(14):146803. doi: 10.1103/PhysRevLett.95.146803. Epub 2005 Sep 29.
We report a first principles analysis of electron-phonon coupling in molecular devices under external bias voltage and during current flow. Our theory and computational framework are based on carrying out density functional theory within the Keldysh nonequilibrium Green's function formalism. Using a molecular tunnel junction of a 1,4-benzenedithiolate molecule contacted by two aluminum leads as an example, we analyze which molecular vibrational modes are most relevant to charge transport under nonequilibrium conditions. We find that the low-lying modes are most important. As a function of bias voltage, the electron-phonon coupling strength can change drastically while the vibrational spectrum changes at a few percent level.
我们报告了在外部偏置电压下以及电流流动过程中分子器件中电子 - 声子耦合的第一性原理分析。我们的理论和计算框架基于在凯尔迪什非平衡格林函数形式体系内进行密度泛函理论。以由两个铝引线接触的1,4 - 苯二硫醇盐分子的分子隧道结为例，我们分析了在非平衡条件下哪些分子振动模式与电荷传输最为相关。我们发现低能模式最为重要。作为偏置电压的函数，电子 - 声子耦合强度可能会急剧变化，而振动光谱仅在百分之几的水平上发生变化。
