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dc.contributor.authorSouza, Amaury De Melo
dc.contributor.authorRungger, Ivan
dc.contributor.authorPontes, Renato Borges
dc.contributor.authorRocha, Alexandre Reily
dc.contributor.authorDa Silva, Antônio José Roque
dc.contributor.authorSchwingenschlögl, Udo
dc.contributor.authorSanvito, S.
dc.date.accessioned2015-08-03T11:44:20Z
dc.date.available2015-08-03T11:44:20Z
dc.date.issued2014
dc.identifier.issn20403364
dc.identifier.doi10.1039/c4nr04081c
dc.identifier.urihttp://hdl.handle.net/10754/563260
dc.description.abstractIt is often assumed that the hydrogen atoms in the thiol groups of a benzene-1,4-dithiol dissociate when Au-benzene-1,4-dithiol-Au junctions are formed. We demonstrate, by stability and transport property calculations, that this assumption cannot be made. We show that the dissociative adsorption of methanethiol and benzene-1,4-dithiol molecules on a flat Au(111) surface is energetically unfavorable and that the activation barrier for this reaction is as high as 1 eV. For the molecule in the junction, our results show, for all electrode geometries studied, that the thiol junctions are energetically more stable than their thiolate counterparts. Due to the fact that density functional theory (DFT) within the local density approximation (LDA) underestimates the energy difference between the lowest unoccupied molecular orbital and the highest occupied molecular orbital by several electron-volts, and that it does not capture the renormalization of the energy levels due to the image charge effect, the conductance of the Au-benzene-1,4-dithiol-Au junctions is overestimated. After taking into account corrections due to image charge effects by means of constrained-DFT calculations and electrostatic classical models, we apply a scissor operator to correct the DFT energy level positions, and calculate the transport properties of the thiol and thiolate molecular junctions as a function of the electrode separation. For the thiol junctions, we show that the conductance decreases as the electrode separation increases, whereas the opposite trend is found for the thiolate junctions. Both behaviors have been observed in experiments, therefore pointing to the possible coexistence of both thiol and thiolate junctions. Moreover, the corrected conductance values, for both thiol and thiolate, are up to two orders of magnitude smaller than those calculated with DFT-LDA. This brings the theoretical results in quantitatively good agreement with experimental data.
dc.description.sponsorshipResearch reported in this publication was supported by the King Abdullah University of Science and Technology (KAUST). The Trinity College High-Performance Computer Center and the HPC cluster at Universidade de Sao Paulo provided the computational resources.
dc.publisherRoyal Society of Chemistry (RSC)
dc.titleStretching of BDT-gold molecular junctions: Thiol or thiolate termination?
dc.typeArticle
dc.contributor.departmentPhysical Sciences and Engineering (PSE) Division
dc.contributor.departmentMaterials Science and Engineering Program
dc.contributor.departmentComputational Physics and Materials Science (CPMS)
dc.identifier.journalNanoscale
dc.contributor.institutionSchool of Physics, Trinity College Dublin, College Green D2, Ireland
dc.contributor.institutionInstituto de Física, Universidade Federal de Goiás, Campus SamambaiaGoiânia-GO, Brazil
dc.contributor.institutionInstituto de Física Teórica, Universidade Estadual Paulista, Barra-FundaSão Paulo, SP, Brazil
dc.contributor.institutionInstituto de Física, Universidade de São Paulo, Cidade Universitária, Rua do MatãoSão Paulo, SP, Brazil
dc.contributor.institutionLaboratório Nacional de Luz Sincroton LNLSCampinas, SP, Brazil
dc.identifier.arxividarXiv:1410.0771
kaust.personSchwingenschlögl, Udo


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