2018 - Sustainable Industrial Processing Summit & Exhibition
4-7 November 2018, Rio Othon Palace, Rio De Janeiro, Brazil
| A Computational Study of π-π Stacking Interactions Using High-Level Ab Initio Methods and Density Functional Methods Adelia Aquino1; 1TIANJIN UNIVERSITY, Tianjin, China; PAPER: 379/SISAM/Invited (Oral) SCHEDULED: 16:20/Tue./Copacabana A (150/1st) ABSTRACT: High level ab initio interaction energy calculations based on coupled cluster methods with singles and doubles and non-iterative singles (CCSD(T)) and scaled opposite-spin (SOS) Møller-Plesset perturbation theory (MP2) were performed on several sandwich (S) and the slipped parallel (SP) dimers of selected polyaromatic hydrocarbons (PAHs) up to coronene encircled by three sets of benzene rings (coronene circum-3 dimer, 300 carbon atoms) in an attempt to reliably compute the π-π stacking interactions of extended aromatic systems [1,2]. Results are compared with density functional theory (DFT) using the B3LYP functional and the D3 dispersion correction. Comparison of coupled cluster with SOS-MP2 results show good agreement for smaller linear polyacenes (benzene to anthracene dimer), whereas the unscaled MP2 results demonstrate a well-known overshooting of interaction energies. The SOS-MP2 method reproduces interring distances quite well in comparison to higher level results. Thus, investigations on the stacking properties of larger systems have been continued at this computational level. It was found that the coronene circum-2 dimer complex has a sandwich biconcave structure with a stronger interaction (smaller distances) in the center. The distance of 3.33 Ao is significantly smaller than the van der Waals distance of ~3.60 Ao. Slipped parallel structures have been investigated as well. They are in all cases more stable than the sandwich structures. Comparison in terms of inter-sheet bond distances and interaction energies with sandwich structures will be discussed in the presentation References: [1] D. Umadevi, S. Panigrahi and G. N. Sastry, Acc. Chem. Res. 47 (2014) 2574-2581. [2] X. K. Lu, M. F. Yu, H. Huang and R. S. Ruoff, Nanotechnology 10 (1999) 269-272. |
