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dc.contributor.authorSouza, Amaury de Melo
dc.contributor.authorRungger, Ivan
dc.contributor.authorPontes, Renato Borges
dc.contributor.authorRocha, Alexandre Reily [UNESP]
dc.contributor.authorRoque da Silva, Antonio Jose
dc.contributor.authorSchwingenschloeegl, Udo
dc.contributor.authorSanvito, Stefano
dc.identifier.citationNanoscale. Cambridge: Royal Soc Chemistry, v. 6, n. 23, p. 14495-14507, 2014.
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.en
dc.description.sponsorshipKing Abdullah University of Science and Technology (KAUST)
dc.publisherRoyal Soc Chemistry
dc.sourceWeb of Science
dc.titleStretching of BDT-gold molecular junctions: thiol or thiolate termination?en
dcterms.rightsHolderRoyal Soc Chemistry
dc.contributor.institutionTrinity Coll Dublin
dc.contributor.institutionUniversidade Federal de Goiás (UFG)
dc.contributor.institutionUniversidade Estadual Paulista (Unesp)
dc.contributor.institutionUniversidade de São Paulo (USP)
dc.description.affiliationTrinity Coll Dublin, Sch Phys, AMBER, Coll Green D2, Ireland
dc.description.affiliationTrinity Coll Dublin, CRANN, Coll Green D2, Ireland
dc.description.affiliationUniv Fed Goias, Inst Fis, BR-74001970 Goiania, Go, Brazil
dc.description.affiliationUniv Estadual Paulista, Inst Fis Teor, BR-01140070 Sao Paulo, Brazil
dc.description.affiliationUniv Sao Paulo, Inst Fis, BR-05508090 Sao Paulo, Brazil
dc.description.affiliationLNLS, BR-13083970 Campinas, SP, Brazil
dc.description.affiliationKAUST, PSE Div, Thuwal 239556900, Saudi Arabia
dc.description.affiliationUnespUniv Estadual Paulista, Inst Fis Teor, BR-01140070 Sao Paulo, Brazil
dc.rights.accessRightsAcesso restrito
unesp.campusUniversidade Estadual Paulista (Unesp), Instituto de Física Teórica (IFT), São Paulopt
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