Modeling and analysis of the (H2C2)n(HCN)m gas-phase clusters by ab initio and DFT computational methods for astrochemical applications

Abstract

Among the different purposes of astrochemistry, there is the study of chemical processes in the Interstellar Medium (ISM), and the corresponding reaction pathways that may lead to the formation of biological molecules. Within this framework, in recent years some gas-phase clusters have been investigated since they may constitute the first steps involved in these reaction networks. The study presented in this thesis aims to illustrate different types of clusters involving hydrogen cyanide and acetylene, such molecules present a lot of interesting interactions including Van der Waals and dispersion forces. For each cluster, geometry, energy and other parameters have been optimized through many ab initio and Density Function Theory (DFT) methods (also including some of the semiempirical Grimme's density functionals). Finally, non-covalent interactions were investigated through the Quantum Theory of Atoms in Molecules (QTAIM) to identify the nature of the interactions that lead to the stability of (H2C2)n, (HCN)m and mixed structures (H2C2)n(HCN)m.