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arXiv · 1607.04464

Improvements on non-equilibrium and transport Green function techniques: the next-generation transiesta

Nick 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 ($N_e\ge1$) with individual chemical potentials and electronic temperatures. We describe its novel methods for electrostatic gating, contour opti- mizations, and assertion of charge conservation, as well as the newly implemented algorithms for optimized and scalable matrix inversion, performance-critical pivoting, and hybrid parallellization. Additionally, a generic NEGF post-processing code (tbtrans/phtrans) for electron and phonon transport is presented with several novelties such as Hamiltonian interpolations, $N_e\ge1$ 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 $10^6$ atoms on workstation computers. The new features of both codes are demonstrated and bench-marked for relevant test systems.

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Nick Papior, Nicolás Lorente, Thomas Frederiksen, Alberto García, Mads Brandbyge. 2016-07-15. Improvements on non-equilibrium and transport Green function techniques: the next-generation transiesta. https://doi.org/10.1016/j.cpc.2016.09.022

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