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Large-scale electronic transport simulations

Robert A. Bell, Simon M.-M. Dubois, Mike C. Payne and Arash A. Mostofi, Electronic transport calculations in the ONETEP code: implementation and applications, Comput. Phys. Commun. 193, 78 (2015)

Over the last decade, there has been increasing interest in modelling electronic transport at the atomic scale. In particular, the need to capture the physics of emerging nanostructured electronic devices calls for quantum-mechanical simulations. The Landauer-Buttiker formalism coupled with density functional theory (DFT) is used successfully to model a wide range of transport phenomena. Simulations realistic nanoscale devices containing several thousands, or tens of thousands, of atoms whilst retaining the gold-standard plane-wave accuracy remains a challenge.

In this work, we have developed a DFT-based method to investigate Landauer-Buttiker electronic transport in devices containing several thousands of atoms. The implementation is based within the ONETEP linear-scaling DFT code that relies on a minimal set of localised Wannier-like orbitals. As these generalized Wannier functions are optimised with respect to an underlying systematic basis of functions equivalent to a set of plane-waves, the implementation retains the characteristic of controllable accuracy. The method is demonstrated by applying it to study conductivity in carbon nanotube networks and is a step toward the goal of rational design and optimisation of realistic nanoscale devices from first-principles.