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postgraduate thesis: First principles transport study of molecular device

TitleFirst principles transport study of molecular device
Authors
Advisors
Advisor(s):Wang, J
Issue Date2012
PublisherThe University of Hong Kong (Pokfulam, Hong Kong)
Citation
Zhang, L. [张磊]. (2012). First principles transport study of molecular device. (Thesis). University of Hong Kong, Pokfulam, Hong Kong SAR. Retrieved from http://dx.doi.org/10.5353/th_b5089955
AbstractThis thesis discusses DC and AC transport properties of molecular devices from first principles. For dc bias, based on the non-equilibrium Green’s function (NEGF) technique coupled with the density functional theory (DFT), the dc current density distribution of a molecular device Al-C60-Al is numerically investigated from first principles. Due to the presence of non-local pseudo-potential, the conventional definition of current density is not suitable to describe the correct current density profile inside the molecular device. By using the new definition of current density which includes the contribution due to the nonlocal potential, our numerical results show that the new definition of current density J(r) conserves the current. In addition, the current obtained from the current density calculated inside the molecular device equals to that calculated from the Landauer-Büttiker formula. When the external bias is time dependent, a theoretical formalism to study the time dependent transport behavior of molecular device from first principles is proposed based on the non-equilibrium Green’s function (NEGF) and time dependent density functional theory (TDDFT). For the purpose of numerical implementation on molecular devices, a computational tractable numerical scheme is discussed in detail. The transient current of two molecular devices Al-1,4-dimethylbenzene-Al and Al-Benenze-Al are numerically studied from first principles. To overcome the computational complexity due to the memory term, a fast algorithm has been employed to speed up the calculation and CPU time has been reduced from the scaling N^3to N^2 log(_2^2)(N) for the step like pulse, where N is the number of time step in the time evolution of Green’s function.
DegreeDoctor of Philosophy
SubjectMolecular electronics.
Dept/ProgramPhysics
Persistent Identifierhttp://hdl.handle.net/10722/192810

 

DC FieldValueLanguage
dc.contributor.advisorWang, J-
dc.contributor.authorZhang, Lei-
dc.contributor.author张磊-
dc.date.accessioned2013-11-24T02:00:45Z-
dc.date.available2013-11-24T02:00:45Z-
dc.date.issued2012-
dc.identifier.citationZhang, L. [张磊]. (2012). First principles transport study of molecular device. (Thesis). University of Hong Kong, Pokfulam, Hong Kong SAR. Retrieved from http://dx.doi.org/10.5353/th_b5089955-
dc.identifier.urihttp://hdl.handle.net/10722/192810-
dc.description.abstractThis thesis discusses DC and AC transport properties of molecular devices from first principles. For dc bias, based on the non-equilibrium Green’s function (NEGF) technique coupled with the density functional theory (DFT), the dc current density distribution of a molecular device Al-C60-Al is numerically investigated from first principles. Due to the presence of non-local pseudo-potential, the conventional definition of current density is not suitable to describe the correct current density profile inside the molecular device. By using the new definition of current density which includes the contribution due to the nonlocal potential, our numerical results show that the new definition of current density J(r) conserves the current. In addition, the current obtained from the current density calculated inside the molecular device equals to that calculated from the Landauer-Büttiker formula. When the external bias is time dependent, a theoretical formalism to study the time dependent transport behavior of molecular device from first principles is proposed based on the non-equilibrium Green’s function (NEGF) and time dependent density functional theory (TDDFT). For the purpose of numerical implementation on molecular devices, a computational tractable numerical scheme is discussed in detail. The transient current of two molecular devices Al-1,4-dimethylbenzene-Al and Al-Benenze-Al are numerically studied from first principles. To overcome the computational complexity due to the memory term, a fast algorithm has been employed to speed up the calculation and CPU time has been reduced from the scaling N^3to N^2 log(_2^2)(N) for the step like pulse, where N is the number of time step in the time evolution of Green’s function.-
dc.languageeng-
dc.publisherThe University of Hong Kong (Pokfulam, Hong Kong)-
dc.relation.ispartofHKU Theses Online (HKUTO)-
dc.rightsThe author retains all proprietary rights, (such as patent rights) and the right to use in future works.-
dc.rightsCreative Commons: Attribution 3.0 Hong Kong License-
dc.source.urihttp://hub.hku.hk/bib/B50899557-
dc.subject.lcshMolecular electronics.-
dc.titleFirst principles transport study of molecular device-
dc.typePG_Thesis-
dc.identifier.hkulb5089955-
dc.description.thesisnameDoctor of Philosophy-
dc.description.thesislevelDoctoral-
dc.description.thesisdisciplinePhysics-
dc.description.naturepublished_or_final_version-
dc.identifier.doi10.5353/th_b5089955-
dc.date.hkucongregation2013-

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