Enabling Ab-Initio Molecular Dynamics under Bias: The CP2K+SMEAGOL Interface for Integrating Density Functional Theory and Non-Equilibrium Green Functions

Density functional theory (DFT) combined with non-equilibrium Greens functions (NEGF) is a powerful approach to model quantum transport under external bias potentials, at reasonable computational cost. In this work we present a new interface between the popular mixed Gaussian/plane wave electronic structure package CP2K and the NEGF code SMEAGOL, the most feature-rich implementation of DFT-NEGF available for CP2K to-date. The CP2K+SMEAGOL interface includes the implementation of current induced forces. We verify this implementation for a variety of systems: an infinite 1D Au wire, a parallel-plate capacitor and a Au-H2-Au junction. We find good agreement with SMEAGOL calculations performed with SIESTA for the same systems, and with the example of a solvated Au wire demonstrate for the first time that DFT-NEGF can be used to perform molecular dynamics simulations under bias of large-scale condensed phase systems under realistic operating conditions.