Improvements on non-equilibrium and transport Green function techniques: The next-generation TRANSIESTA

Nick Rübner Papior, Nicolás Lorente, Thomas Frederiksen, Alberto García, Mads Brandbyge

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Abstract

We present novel methods implemented within the non-equilibrium Green function code (NEGF) TRANSIESTA based on density functional theory (DFT). Our flexible, next-generation DFT–NEGF code handles devices with one or multiple electrodes (Ne≥1) with individual chemical potentials and electronic temperatures. We describe its novel methods for electrostatic gating, contour optimizations, and assertion of charge conservation, as well as the newly implemented algorithms for optimized and scalable matrix inversion, performance-critical pivoting, and hybrid parallelization. Additionally, a generic NEGF “post-processing” code (TBTRANS/PHTRANS) for electron and phonon transport is presented with several novelties such as Hamiltonian interpolations, Ne≥1 electrode capability, bond-currents, generalized interface for user-defined tight-binding transport, transmission projection using eigenstates of a projected Hamiltonian, and fast inversion algorithms for large-scale simulations easily exceeding 106 atoms on workstation computers. The new features of both codes are demonstrated and bench-marked for relevant test systems.
Original languageEnglish
JournalComputer Physics Communications
Volume212
Pages (from-to)8-24
Number of pages17
ISSN0010-4655
DOIs
Publication statusPublished - 2017

Bibliographical note

© 2016 The Authors. Published by Elsevier B.V.
This is an open access article under the CC BY-NC-ND license

Keywords

  • Density functional theory
  • Green function
  • Non equilibrium
  • Transport

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