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Theoretical modelin...
Theoretical modeling of scanning tunneling microscopy
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- Gustafsson, Alexander, 1982- (author)
- Linnéuniversitetet,Institutionen för fysik och elektroteknik (IFE),Condensed Matter Physics
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Paulsson, Magnus (thesis advisor)
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- Iribas Cerdá, Jorge, Dr. (opponent)
- Materials Science Institute of Matdrid, Spanish National Research Council
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(creator_code:org_t)
- ISBN 9789188357960
- Växjö : Linnaeus University Press, 2017
- English 133 s.
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Series: Linnaeus University Dissertations ; 300
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Abstract
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- The main body of this thesis describes how to calculate scanning tunneling microscopy (STM) images from first-principles methods. The theory is based on localized orbital density functional theory (DFT), whose limitations for large-vacuum STM models are resolved by propagating localized-basis wave functions close to the surface into the vacuum region in real space. A finite difference approximation is used to define the vacuum Hamiltonian, from which accurate vacuum wave functions are calculated using equations based on standard single-particle Green’s function techniques, and ultimately used to compute the conductance. By averaging over the lateral reciprocal space, the theory is compared to a series of high-quality experiments in the low- bias limit, concerning copper surfaces with adsorbed carbon monoxide (CO) species and adsorbate atoms, scanned by pure and CO-functionalized copper tips. The theory compares well to the experiments, and allows for further insights into the elastic tunneling regime.A second significant project in this thesis concerns first-principles calculations of a simple chemical reaction of a hydroxyl (oxygen-deuterium) monomer adsorbed on a copper surface. The reaction mechanism is provided by tunneling electrons that, via a finite electron-vibration coupling, trigger the deuterium atom to flip between two nearly identical configurational states along a frustrated rotational motion. The theory suggests that the reaction primarily occurs via nuclear tunneling for the deuterium atom through the estimated reaction barrier, and that over-barrier ladder climbing processes are unlikely.
Subject headings
- NATURVETENSKAP -- Fysik -- Den kondenserade materiens fysik (hsv//swe)
- NATURAL SCIENCES -- Physical Sciences -- Condensed Matter Physics (hsv//eng)
Keyword
- Scanning tunneling microscopy
- Computational models
- Quantum tunneling
- Green's functions
- Density functional theory
- Condensed Matter Physics
- Kondenserade materians fysik
Publication and Content Type
- vet (subject category)
- dok (subject category)
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