Regensburg 2016 – scientific programme
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 37: Organic-Inorganic Systems II: Energy Level Alignment (organized by O)
CPP 37.4: Talk
Wednesday, March 9, 2016, 11:30–11:45, S054
Density-Matrix Derived van der Waals Interactions: Many-Body Dispersion goes Mesoscale — •Martin Stöhr1,2, Georg Michelitsch1, John Tully2, Karsten Reuter1, and Reinhard Maurer2 — 1Technische Universität München — 2Yale University
The applicability of highly accurate quantum chemical simulation methods is limited to systems of small to moderate size. Density-Functional Theory (DFT), but also more approximate, semi-empirical methods such as Density-Functional based Tight-Binding (DFTB) have shown great success in addressing systems at longer time and length scales. However, a severe drawback of DFTB and many prevalent DFT functionals is the neglect of dispersion interactions, which is particularly consequential for the simulation of e.g. hybrid inorganic-organic systems. Here, we propose a novel approach to obtain effective C6 coefficients in the context of the Tkatchenko-Scheffler dispersion correction scheme [1]. The modified scheme derives atomic dispersion parameters directly from the density-matrix and is thus readily applicable to both full DFT and semi-empirical methods like DFTB, where the electron density is not explicitly constructed. At a fraction of the computational workload of a density-based approach, the scheme yields equally accurate dispersion energies up to the many-body dispersion level for intermolecular interactions in gas-phase and molecular crystals. We exemplify the robustness of the scheme by addressing organic-inorganic interfaces with DFTB using a minimal basis set. [1] A. Tkatchenko and M. Scheffler, Phys. Rev. Lett. 102, 073005 (2009).