  Based on the complex absorbing potential (CAP) method, a Lorentzian expansion
scheme is developed to express the self-energy. The CAP-based Lorentzian
expansion of self-energy is employed to solve efficiently the Liouville-von
Neumann equation of one-electron density matrix. The resulting method is
applicable for both tight-binding and first-principles models, and is used to
simulate the transient currents through graphene nanoribbons and a benzene
molecule sandwiched between two carbon-atom-chains.
