2026-09-23T00:09:50Zhttps://api.repository.cam.ac.uk/server/oai/requestoai:www.repository.cam.ac.uk:1810/2921082021-04-21T19:46:26Zcom_1810_198332com_1810_256064col_1810_214775
Linear-Scaling Density Functional Theory and Theoretical Electron Energy Loss Spectroscopy Investigations of Surfaces and Defects in Nanomaterials
10.17863/CAM.39263
Tait, Edward William
Hine, Nicholas
Ducati, Caterina
This work presents a method for the computation of electron energy loss
spectra for large systems using the onetep code.
The foundations of density functional theory will be discussed, with a
focus on the linear scaling methods employed by onetep. A method for the
prediction of spectra will be shown, with emphasis on the construction of
the matrix elements needed. This method is tested against both other DFT
codes and experiment.
Once the ability of onetep to predict EEL spectra has been established
the code is used to predict the spectra associated with oxygen vacancy defects
in the anatase (101) surface. These spectra are found to agree with the
limited experimental data available. EEL spectra for nitrogen dopants in
anatase are also predicted, based on literature geometries for these.
The energetics of the oxygen vacancy is also explored, using the ability
of onetep to perform calculations on large cells to address elastic finite size
effects and employing a correction scheme to remove electrostatic finite size
effects.
Finally, the properties of an extended grain boundaries defect in GaAs
were investigated, focussing on properties relevant for optoelectronics.
University of Cambridge
2019-05-22
Thesis
Doctoral
Doctor of Philosophy (PhD)
en
Supported by the EPSRC Cambridge NanoDTC, EP/G037221/1
https://www.repository.cam.ac.uk/handle/1810/292108
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EELS
Electron Energy Loss Spectroscopy
ONETEP
DFT
Linear Scaling
Density Functional Theory
Anatase
Titanium Dioxide
LS-DFT
Defect
Surface Defect
Formation Energy