Long-range Correlation Energy in the Interaction of Molecules with Surfaces

By exploiting the fluctuation-dissipation theorem of DFT and a formally exact decomposition of the density-density linear response function evaluated at imaginary frequency, subsystem Density Functional Theory makes an excellent platform for developing non-local long-range correlation energy functionals [1,2]. We present a computational protocol to extract embedded C6 coefficients for molecules surrounded by complex environments from a real-time subsystem TDDFT simulation [3]. The C6 coefficients fully account for environmental screening effects through the many-body response [4]. We showcase a pilot calculation of the C6 coefficient of Benzene adsorbed on monolayer MoS2 and we show a surface enhancement of the van der Waals interaction between two benzene molecules nearby a MoS2 surface of 11 meV compared to the interaction estimated from C6 coefficients derived from isolated benzene molecules.
[1] R. Kevorkyants, H. Eshuis, and M. Pavanello, J. Chem. Phys. 141, 044127 (2014)
[2] A. Krishtal, D. Sinha, A. Genova, and M. Pavanello, J. Phys.: Condens. Matter, 27, 183202 (2015)
[3] A. Umerbekova, S.-F. Zhang, S. P. Kumar and M. Pavanello, Eur. Phys. J. B, 91, 214 (2018)
[4] A. Umerbekova and M. Pavanello, in preparation.