Convergence in quantum transport calculations: Localized atomic orbitals versus nonlocalized basis sets

Abstract

The convergence and basis set dependence of quantum transport calculations is studied using localized atomic orbitals and nonlocalized basis sets. The nonequilibrium Green's function formalism and ground-state density-functional theory are used in the calculations. Numerical examples show that the extended nonlocalized basis sets give more accurate results with much lower basis dimension than the atomic orbitals. Examples also show that a low-dimensional atomic orbital basis can also be accurate provided that the self-consistent ground-state potential is accurately calculated.