Properties of molecules in tunnel junctions

dc.check.embargoformatNot applicableen
dc.check.infoNo embargo requireden
dc.check.opt-outNot applicableen
dc.check.reasonNo embargo requireden
dc.check.typeNo Embargo Required
dc.contributor.advisorGreer, James C.en
dc.contributor.authorYeriskin, Irene
dc.contributor.funderIrish Research Council for Science Engineering and Technologyen
dc.date.accessioned2013-10-07T16:35:00Z
dc.date.available2013-10-07T16:35:00Z
dc.date.issued2013
dc.date.submitted2013
dc.description.abstractMolecular tunnel junctions involve studying the behaviour of a single molecule sandwiched between metal leads. When a molecule makes contact with electrodes, it becomes open to the environment which can heavily influence its properties, such as electronegativity and electron transport. While the most common computational approaches remain to be single particle approximations, in this thesis it is shown that a more explicit treatment of electron interactions can be required. By studying an open atomic chain junction, it is found that including electron correlations corrects the strong lead-molecule interaction seen by the ΔSCF approximation, and has an impact on junction I − V properties. The need for an accurate description of electronegativity is highlighted by studying a correlated model of hexatriene-di-thiol with a systematically varied correlation parameter and comparing the results to various electronic structure treatments. The results indicating an overestimation of the band gap and underestimation of charge transfer in the Hartree-Fock regime is equivalent to not treating electron-electron correlations. While in the opposite limit, over-compensating for electron-electron interaction leads to underestimated band gap and too high an electron current as seen in DFT/LDA treatment. It is emphasised in this thesis that correcting electronegativity is equivalent to maximising the overlap of the approximate density matrix to the exact reduced density matrix found at the exact many-body solution. In this work, the complex absorbing potential (CAP) formalism which allows for the inclusion metal electrodes into explicit wavefunction many-body formalisms is further developed. The CAP methodology is applied to study the electron state lifetimes and shifts as the junction is made open.en
dc.description.statusNot peer revieweden
dc.description.versionAccepted Version
dc.format.mimetypeapplication/pdfen
dc.identifier.citationYeriskin, I. 2013. Properties of molecules in tunnel junctions. PhD Thesis, University College Cork.en
dc.identifier.endpage165
dc.identifier.urihttps://hdl.handle.net/10468/1242
dc.language.isoenen
dc.publisherUniversity College Corken
dc.rights© 2013, Irene Yeriskinen
dc.rights.urihttp://creativecommons.org/licenses/by-nc-nd/3.0/en
dc.subjectComputational modellingen
dc.subjectSingle molecule junctionsen
dc.subjectTunnel junctionsen
dc.subjectElectronegativityen
dc.subject.lcshQuantum chemistryen
dc.thesis.opt-outfalse*
dc.titleProperties of molecules in tunnel junctionsen
dc.typeDoctoral thesisen
dc.type.qualificationlevelDoctoralen
dc.type.qualificationnamePhD (Science)en
ucc.workflow.supervisorjim.greer@tyndall.ie*
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