In the past two decades, significant progress has been achieved in the large-scale fabrication of nanostructures where quantum transport properties of charge and spin are closely coupled to the discreteness of the device material. Multitudes of emerging device concepts and new materials with interesting application potential have been discovered. In order to understand the experimental data and device physics of nanoelectronics, an important task is to develop appropriate theoretical formalisms and associated modeling tools which are capable of making quantitative and material specific predictions of device characteristics without any phenomenological parameters. Here we review the atomistic modeling method based on carrying out density functional theory (DFT) within the nonequilibrium Green's function (NEGF) formalism. Since its original implementation ten years ago, the NEGF-DFT technique has emerged as a very powerful and practically very useful method for predicting nonlinear and nonequilibrium quantum transport properties of nanoelectronics. Recent new developments concerning nonequilibrium disorder scattering will also be presented. Large-scale and scalable computations have allowed NEGF-DFT to model Si structures reaching the present day realistic channel sizes.