Comparison of van der Waals corrected and sparse-matter density functionals for the metal-free phthalocyanine/gold interface.

In this paper, we report a systematic study on the effect of different van der Waals dispersion correction methods in conjunction with Density Functional Theory on the adsorption characteristics of a monolayer of metal-free phthalocyanine on Åu(l 11). The chosen dispersion corrections were DFT-D2, the Tkatchenko-Scheffler method with and without self-consistent screening, and four sparse-matter density functionals. Å comparison among different dispersion corrections was performed and the results are related to available experimental scanning tunnel microscopy and x-ray standing-wave measurements for similar molecules on Åu(l 11). We found that the Tkatchenko-Scheffler method as well as a sparse-matter density functional which employs the exchange potential of optB86b and the nonlocal correlation of Dion describe the adsorbed system, e.g., electronic and geometric structure with an adsorption distance of 3.3 Å, reasonably well within moderate computational costs. [ABSTRACT FROM AUTHOR]