上海科技大学知识管理系统

As important progress for simulating realistic device materials, we report the first-principles nonequilibrium dynamical cluster theory for simulating the quantum transport properties of nanoelectronics with inevitable disordered defects or dopants. In this method, we formulate the nonequilibrium dynamical cluster theory in Keldysh's Green's function representation, and implement it with the exact muffin-tin orbital based density functional theory. With this method, the important correlation effects of disordered scattering and short-range order effects can be effectively treated for the nonequilibrium electronic structure and quantum transport calculations of devices under finite bias. Moreover, a double-energy-contour technique is devised to considerably improve the numerical convergence in the nonequilibrium electron structure calculation. As the demonstration, the first-principles nonequilibrium dynamical cluster theory is applied to calculate Cu/Co junction with disordered interface and Fe/vacuum/Fe magnetic tunnel junction with surface roughness. We find that a sizable transmission decrease can be induced by including the correlation effects of disorders of few layers in the Cu/Co junction, presenting the important transport channel closing due to disordered quantum interference. For Fe/vacuum/Fe junction, we find that short-range order of surface roughness, with the important clustering and anticlustering tendencies, can dramatically change the transmission properties compared to the case of (or close to) complete randomness. The development of first-principles nonequilibrium dynamical cluster theory provides an important approach for analyzing the process-dependent device performance, extending the capability of first-principles quantum transport simulation.