NSCI SI2-SSE: Multiscale Software for Quantum Simulations of Nanostructured Materials and Devicentitled Item BernholcJerzy BriggsE. L. LuW. KelleyC. T. XiaoZ. ZhangJ. 2018 We develop open-source software for quantum simulations of nanostructured materials and devices, available at <a href="http://www.rmgdft.org/">www.rmgdft.org</a>. RMG scales to over 100,000 cores and 10,000 GPUs, while also while also being portable across Linux, Windows and MacIntosh computers. The base software has been fully refactored, resulting in a templated and threaded code that can be easily adapted to emerging high-performance architectures envisioned by the NSCI roadmap. RMG solves the density-functional-theory equations using real-space grids, a multigrid pre-conditioner, and subspace diagonalization. For calculating device performance, it uses the non-equilibrium Green’s function formalism with full DFT accuracy.