Download or read book Applications of Novel and Efficient Computational Methods to Uravel Structure-property Relationships in Complex Molecules written by Sibali Debnath and published by . This book was released on 2020 with total page 242 pages. Available in PDF, EPUB and Kindle. Book excerpt: The last three decades have witnessed immense progress in the development of a wide range of ab initio quantum chemical methods to calculate the electronic structures and properties of molecular systems. These sophisticated methods are routinely used in practice to obtain the properties of small molecules within chemical accuracy. However, the steep rise of computational cost associated with such methods with increase in system size prohibits their applicability for large molecular systems. To this end, development of composite methods which could efficiently reduce the computational scaling has become a major focus of study in the field of quantum chemistry. In this dissertation, we present two types of composite methods developed by our group which have been implemented and used for two different applications. The first application involves computing accurate bond dissociation energies (BDEs) using an error-cancellation scheme, known as "connectivity-based hierarchy (CBH)", for biofuel components. The second application involves benchmarking of "Molecules-in-Molecules (MIM)" fragmentation method for large supramolecular systems, such as foldamers and macrocycles as well as their complexes with anions. The composite methods mentioned above can be successfully applied to investigate many problems. Nevertheless, gaining detailed insights on the weak intermolecular interactions present in supramolecular systems has its own set of challenges. In this context, applications using a different class of computational methods, which include both quantum mechanical (QM) calculations and molecular dynamics (MD) simulations, have been employed to understand the complex phenomena of supramolecular self-assembly. A good synergistic relationship between QM and MD has been established by developing customized force field (FFs) parameters using quantum chemical calculations. The final part of the dissertation computationally explores the anion recognition properties of macrocycles and shape-dynamic foldamers. An important observation from our studies on such systems is that the structure-function relationships of host molecules are significantly influenced by external stimuli, such as solvent polarity or the size of the anionic guests. Overall, these findings add fundamental insights important for developing strategies to design new functional materials for real life applications in the field of supramolecular science.