Investigation on the Origin of Dispersion Interaction in Weakly Bound Phenylacetylene•CnHm clusters using dispersion corrected density functional calculations

Halder, Shouvik and Maity, Surajit (2019) Investigation on the Origin of Dispersion Interaction in Weakly Bound Phenylacetylene•CnHm clusters using dispersion corrected density functional calculations. Masters thesis, Indian institute of technology Hyderabad.

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Abstract

Dispersion interaction is the attractive forces between an instantaneous dipole and induced dipole, generated due to the correlated movement of electrons in interacting molecules. Dispersion dominated intermolecular interaction has been the topic of interest among scientific communities to describe physical, chemical, and biological phenomena of diverse chemical systems such as crystal packing, protein folding, conformations and configurations of many biomolecules and polymers. Understanding the nature and origin of the interaction requires both experimental and theoretical investigations and a mutual agreement between them. In this project, we are going to investigate the dispersion interaction of PHA-CnHm clusters, where PHA is a non-polar S molecule with π-electron density which can form C-H/π bound complexes which are significantly different than the conventional hydrogen bonds like O-H/π or N-H/π. We have used density functional theory with dispersion correction using B3LYP-D3, PBE0-D3 functionals with def2-TZVPP and aug-cc-pVDZ basis sets to calculate the electronic structures and stabilization energies with the help of TURBOMOLE software. The intermolecular dispersion terms are calculated using two different numerical models as functions of (i) molecular dispersion and (ii) total dispersion by atomic polarizability. The model with total dispersion energy providing a good correlation with the binding energy of the cluster than molecular dispersion model. Success of this method, lead us to propose a novel numerical method based on the contribution by whole sets of atoms, which is able to determine the origin of C-H/π interaction.

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