Calculation of monolayer structures of hydrocarbon chains on transition metal dichalcogenides: Dotriacontane onMoSe2

In situ scanning tunneling microscopy at the interface between atomically flat solid surfaces and solutions containing alkyl chains or alkyl derivatives show that the solute molecules often adsorb from solution to form dense crystalline monolayers at the liquid-solid interface. The structure of these layers depends on the nature of the substrate, and thus cannot be predicted from simple packing considerations alone. As an example of a theoretical approach to this problem on the atomic level, we present a calculation of the monolayer structure of dotriacontane on ${\mathrm{MoSe}}_2$. We carry out energy minimizations of periodic clusters of dotriacontane on ${\mathrm{MoSe}}_2$, where the potential energy is based on ab initio second-order Mo/ller-Plesset perturbation calculations of the adsorbate-substrate interactions combined with a phenomenological force field description of the intra-adsorbate interactions. The resulting adsorbate structure is in excellent agreement with the experimentally observed structure.