Theoretical investigation of intermolecular interactions between CNT, SiCNT and SiCGeNT nanomaterials with vinyl chloride molecule: A DFT, NBO, NCI, and QTAIM study

Vinyl chloride (VCM) or chloroethylene is reactive in the gaseous state and its adsorption with pristine armchair (5,5) carbon nanotube (CNT) and silicon carbide nanotube (SiCNT) has been studied. Germanium (Ge) element as an impurity has been introduced to silicon carbide structure (i.e. SiCGeNT) so as to increase the reactivity of the surface of SiCNT and thus increase the sensitivity of the adsorbent during the adsorption process. The B3LYPD3(GD3BJ) hybrid functional has been used to optimize the isolated nanostructures and vinyl chloride as well as their clusters (gas/nanotube). In addition, energy single-point calculations were performed using omega B97XD, PBE0, B3LYP-D3(GD3BJ), and M06-2X functionals. The selected basis function is 6-311G(d), which is a good approximation to cover the integration space with respect to the constituent atoms of the molecules studied in this research. Wave function analysis including non-covalent interaction (NCI), natural bond orbital (NBO), and quantum theory of atoms in molecules (QTAIM), have also been done to reveal the intermolecular interactions nature. The results of these analyses, which are calculated using B3LYP-D3(GD3BJ)/6-311G(d) level of theory, are in agreement with each other and emphasize that among the mentioned nanotubes, silicon carbide nanotube doped with Ge element is more sensitive with respect to gas adsorption. Therefore, it will be a good option to design and build a nanosensor.