Potential energy surface of the thiophene pentamer and non-covalent interactions

Theoretical understanding of thiophene clusters is very important for molecular understanding of thiophene as solvent and for determining the thermodynamics properties of the solvent. However, no investigations on thiophene clusters have been reported previously in the literature. We have performed in this work an ab initio computational study to understand the interactions taking place in thiophene clusters using the thiophene pentamer. We started by generating possible structures using classical molecular dynamics followed by full optimization at the ab initio MP2/aug-cc-pVDZ level of theory. Relative energies and temperature-dependent isomer distribution of the investigated structures have been reported. Finally, we have performed a quantum theory of atoms in molecule (QTAIM) analysis to identify all non-covalent bondings that are responsible for the stability of the structures of the thiophene pentamer. The results show that six different types of non-covalent interactions could be found in thiophene pentamer depending on the structure.