Past Events

Abstract

With the rapid development of technology, the classical equation of motion is no longer applicable in nanoscales and in most of time it operates under a nonlinear regime. For mesoscopic systems, from a technical view, they are not only interesting but also provide us with perfect models to understand fundamental physics. Nowadays due to its considerable significance, the comprehension of nonlinear dynamics in mesoscopic systems has become an important research field.

The seminar will talk about two different theoretical frameworks to investigate nonlinear transport phenomenon in mesoscopic systems from first principles. Specifically, by combining non-equilibrium Green’s function formulism and the density functional theory (DFT), a quantum transport theory of dc shot noise in the negative differential resistance region is proposed and studied. Numerically, the model is tested on a carbon wire made of four atoms connecting with two semi-infinite Al leads. For the second framework, kinetic Monte Carlo method coupled with DFT is adopted to study the evolutionary configurations of TiO₂ in 3-dimension by taking the interactions between vacancies and the non-uniform electric field into account. The simulation confirms that the localized electric field induced by vacancy hopping is the main driver of the filament formation at the electroforming stage.