Theoretical investigation of non-covalently bound phenylacetylene-noble gas clusters using dispersion dominated density functional calculations

Sarkar, Saibalendu and Maity, Surajit (2018) Theoretical investigation of non-covalently bound phenylacetylene-noble gas clusters using dispersion dominated density functional calculations. Masters thesis, Indian Institute of Technology, Hyderabad.

Text
Thesis_Msc_CY_3946.pdf - Submitted Version
Restricted to Repository staff only until June 2020.
Download (2MB) | Request a copy

Abstract

The dispersion interaction is one of the most important aspect of non-covalent interaction which is neglected for most of the purposes of study of molecular clusters in spite of having tremendous contribution in the field of chemistry, biochemistry, material science and crystallography. In this theoretical report the origin of this dispersion interaction is studied depending upon several assumptions for the binary cluster phenylacetylene(PHA)∙∙∙X (X= Ne, Ar, Kr, Xe), where the components are non-polar and nearly non-polar, which is expected to show fully dispersion dominated stabilization of the cluster. Binding energy (De) and dissociation energy (D0) are the most reachable parameters for binary clusters experimentally, so the calculations were done for these two parameters using TURBOMOLE 4.3.1 program using DFT-D3 method with the functional B3LYP-D3, B97D-D3, PBE0-D3 and the basis sets def2-TZVPP, aug-cc-pVDZ, and aug-cc-pVTZ. Polarizability of an entity is the property of getting its electron cloud distorted in presence of an external field, and this generates an instantaneous dipole. This dipole is believed to be the driving force for the dispersion dominated complex formation. Certainly there is a correlation between the polarizability and the binding energy. However, polarizability is not the only factor to be taken in consideration, other terms like molecular dispersion (London dispersion term), atom-pair wise dispersion, atom-pair wise polarizability are also deciding factors for the binding energy. The vertical distances between the PHA plane and the X atoms are seemed to be quite identical for a particular method. The dispersion contribution is well accounted for the method B3LYP-D3, B97D-D3 whereas the same is underestimated for PBE0-D3. The zero-point energy though not good contributors to the complexes other than non-covalent complexes, but here gives a substantial contribution of nearly 12% for the B3LYP-D3/def2-TZVPP method. Among the all assumptions for dispersion interaction, the best correlation is seemed to be for atom-pair wise polarizability.

[error in script]

IITH Creators: