Improved Understanding of the Adsorption of Aromatic Molecules from Recent meta-GGA’s*

The strong rules and regulations against environmental pollution demand removal of sulphur compounds from the crude petroleum. Since thiophene is the smallest aromatic sulphur-containing compound, it is a natural choice as a test case for simulations. Previous density functional theory studies have been proven a useful tool to describe the first step toward C-S bond breaking in the hydrodesulphurization (HDS) process at metal surfaces or at different edges of MoS₂ [1]. Earlier computations were done with the PW91 GGA. We are developing a better understanding of this process using two recent and improved meta-GGA’s, SCAN and SCAN+rVV10. At first we are investigating the adsorption of thiophene on transition metals, namely silver and gold, starting from the (100) surface. Our target is to find the stable site of adsorption. In parallel, we are also gaining an insight into the performance of various approximations regarding the interplay between vdW interaction and self-interaction error.
[1] P. G. Moses et al, J. of Catal. 248, 188, (2007).