资源描述：
《First-principles study of the adsorption of atomic H》由会员上传分享，免费在线阅读，更多相关内容在行业资料-天天文库。
1、SurfaceScience459(2000)287±302www.elsevier.nl/locate/suscFirst-principlesstudyoftheadsorptionofatomicHonNi(111),(100)and(110)G.Kresse*,J.HafnerInstitutfuÈrMaterialphysikandCenterforComputationalMaterialScience,UniversitaÈtWien,Sensengasse8/12,A-1090Vienna,AustriaReceived29December1999;acceptedf
2、orpublication21March2000AbstractTheadsorptionofatomicHonNi(111),(100)and(110)surfacesisstudiedusingspin-polarizedgradient-correcteddensity-functionaltheory.FullH-coverageand1/4H-coverageareconsidered.Trendsintheadsorptionenergy,repulsionbetweenadsorbedhydrogenatoms,anddiVusionbarriersarediscuss
3、edindetail.Inaddition,calculationsarepresentedfortheexperimentallyobservedNi(111)(2×2)-2HsuperstructureandfortheNi(110)(1×2)-3Hpairing-rowreconstruction.Theresultsarecomparedwithexperiments,showingagoodagreementwiththestructuralmodelsderivedfromexperimentaldata.Weuseasimulatedannealingapproacht
4、oshowtheglobalstabilityofthepairing-rowreconstruction.©2000ElsevierScienceB.V.Allrightsreserved.Keywords:Chemisorption;Densityfunctionalcalculations;Hydrogenatom;Lowindexsinglecrystalsurfaces;Nickel;Surfacerelaxationandreconstruction1.Introductionbothsurfaces,hydrogenisbelievedtoadsorbintheholl
5、owsite,andthesaturationcoverageisTheadsorptionofHonlow-indexNisurfacesaroundh=1monolayer(ML).Atacoverageofhasbeeninvestigatedexperimentallyandtheoreti-h=0.5ML,the(111)surfaceexhibitsawell-callyformorethan30years.Consequently,ade®ned(2×2)-2Hsuperstructurethatisstableupwealthofexperimentaldatahas
6、accumulated,andtoatemperatureof250K.Onthebasisofearlyaclearpictureofthefeaturesinducedbythelow-energyelectrondiVraction(LEED)measure-hydrogenadsorptionhasemerged.Itisinteresting,ments,itwassuggestedthatthehydrogenatomshowever,thatonlyafewaccuratedensity-func-adsorbinthefccandhcphollows,forminga
7、tionalcalculationshavebeenreportedtodate.Thegraphiticover-layer[1,2].Thisconclusionwasmajormotivationofthepresentworkisto®lllatercon®rmedbyaccuratetensor-LEEDthisgap.(T-LEED)measurements[3],whichalsoindicatethattheNisubstrateexhib
