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ICN2 Thesis Defence: Arsalan Akhtar
Title: Synthesis and electronic characterization of triphenylene-based materials
Directors: Prof. Pablo Ordejon/ Dr Miguel A. Pruneda
Abstract: Addressing energetics of defects is helpful for understanding and identifying them in materials, a challenge that cannot be accomplished solely with experimental techniques. The objective of this thesis is to facilitate the computational study of defect properties ab initio, in particular from Density Functional Theory (DFT). Among the diverse classes of imperfections in materials, we focus on the simplest one, known as point defects: a single missing atom or a single atom impurity in the pristine crystal for example. The objective is to compute the energetics of these defects. Although the number of defects, structures, and configuration combinations pose a tremendous challenge for these computational approaches, the recent development of high-throughput computational materials offers a framework that, together, enables a route to address the problem: state of the art high-performance facilities, platforms for submitting and monitoring thousands of calculations, storing the information in searchable databases, and workflows that automatize the complex combinations of DFT calculations required to solve the electronic structure. With this in mind, I developed all the required Siesta machinery for computing defects´energetics using three particular workflow packages in AiiDA, a powerful platform that enables high-throughput computations in materials. We focus on two specific energies for point defects: Formation Energies and Migration Barrier Energies. The formation energy is the energy required to create the defect, which is related to the probability of having a certain concentration of that defect within the material. In the case of a charged defect, extra careful considerations are needed due to the electrostatic interaction of the charge with its periodic images.

Sep 30, 2022 11:00 AM in Madrid

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