BORIS Theses

BORIS Theses
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A quantum crystallographic approach to study properties of molecules in crystals

Ernst, Michelle (2020). A quantum crystallographic approach to study properties of molecules in crystals. (Thesis). Universität Bern, Bern

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Abstract

In this dissertation, the behaviour of atoms, bonds, functional groups and molecules in vacuo but especially also in the crystal is studied using quantum crystallographic methods. The goal is to deepen the understanding of the properties of these building blocks as well as of the interactions among them, because good comprehension of the microscopic units and their interplay also enables us to explain the macroscopic properties of crystals. The first part (chapters 1-3) and second part (chapter 4) of this dissertation contain theoretical introductions about quantum crystallography. On the one hand, this expression contains the termquantum referring to quantumchemistry. Therefore, the very first chapter gives a brief overview about this field. The second chapter addresses different options to partition quantum chemical entities, such as the electron density or the bonding energy, into their components. On the other hand, quantumcrystallography consists obviously of the crystallographic part and chapter 3 covers these aspects focusing predominantly on X-ray diffraction. A more detailed introduction to quantum crystallography itself is presented in the second part (chapter 4). The third part (chapters 5-9) starts with an overview of the goals of this work followed by the results organized in four chapters. The goal is to deepen the understanding of properties of crystals by theoretically analysing their building block. It is for example studied how electrons and orbitals rearrange due to the electric field in a crystal or how high pressure leads to the formation of new bonds. Ultimately, these findings shall help to rationally design materials with desired properties such as high refractive index or semiconductivity.

Item Type: Thesis
Dissertation Type: Cumulative
Date of Defense: 14 February 2020
Subjects: 500 Science > 540 Chemistry
Institute / Center: 08 Faculty of Science > Department of Chemistry, Biochemistry and Pharmaceutical Sciences (DCBP)
Depositing User: Hammer Igor
Date Deposited: 27 Feb 2020 18:57
Last Modified: 06 Apr 2020 20:22
URI: https://boristheses.unibe.ch/id/eprint/1814

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