The effect of reciprocal-space sampling and basis set quality on the calculated conductance of a molecular junction

Abstract

We perform density functional theory and non-equilibrium Green's function calculations of the conductance of a gold wire and a 1,4-phenylenedimethanethiol (XYL) molecule adsorbed between Au(111) electrodes using the TranSIESTA software package. The effect of varying different computational parameters is investigated. We find that the conductance is more sensitive to the reciprocal-space sampling grid than the quality of the basis set employed. The conductance can vary up to a factor of five as a result of the choice of computational parameters. We report a set of computational parameters that yields a well-converged conductance value.

Keywords:

• Molecular conductance
• Molecular junction
• Density Functional Theory
• Non-equilibrium Green's function

Keywords:

• 73.63.-b
• 73.40.Gk
• 85.35.-p

Acknowledgements

This work was supported by the Australian Research Council and the University of Technology, Sydney. Computing facilities were provided by the Australian Centre for Computing and Communications (ac3) and the Australian Partnership for Advanced Computing (APAC).