甲硫醇在Cu(111)表面的解离吸附密度泛函理论研究.pdf

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1、物理化学学~E(WuliHuaxueXuebao1FebruaryActa脚．-Chim．Sin．2013，29(2)，263—270263[Article]doi：10．3866／PKU．WHXB201211231www．whxb．pku．edu．cn甲硫醇在Cu(1l1)表面的解离吸附：密度泛函理论研究范晓丽刘燕杜秀娟刘崇张超(西北工业大学材料学院，凝固国家重点实验室，西安710072)摘要：采用基于密度泛函理论的第一性原理方法和平板模型研究了CH。SH分子在Cu(111)表面的吸附反应．系统地计算了S原子在不同位置以不同方式吸附的一系列构型，第一次得到未解离的CH。SH分子在

2、Cu(111)表面项位上的稳定吸附构型，该构型吸附属于弱的化学吸附，吸附能为O．39eV．计算同时发现在热力学上解离结构比未解离结构更加稳定．解离的CH。S吸附在桥位和中空位之间。吸附能为0．75—0．77eV．计算分析了未解离吸附到解离吸附的两条反应路径，最小能量路径的能垒为0．57eV．计算结果还表明S—H键断裂后的H原子并不是以H：分子的形式从表面解吸附而是以与表面成键的形式存在．通过比较S原子在独立的CH。SH分子和吸附状态下的局域态密度，发现S—H键断裂后S原子和表面的键合强于未断裂时S原子和表面的键合．关键词：甲硫醇分子：Cu(111)表面：密度泛函理论：吸附构型：解离

3、：局域态密度中图分类号：O641DissociativeAdsorptionofMethanethiolonCu(111)Surface：aDensityFunctionalTheoryStudyFANXiao-LiLIUYanDUXiu—JuanLIUChongZHANGChao(StateKeyLaboratoryofSolidifcationProcessing,SchoolofMaterialsScienceandEngineering,NorthwesternPolytechnicalUniversity,Xi'an710072，PR．China)Abstract：The

4、interactionofmethanethioI(CH3SH)moleculeswiththeCu(111)surfacewasinvestigatedusingafIrst—principlesmethodbasedondensityfunctionaltheory．andaslabmode1．AseriesofpossibleadsorptionconfigurationsconstructedusingSatomsondifferentsiteswithdifferenttiltangleswerestudied．1twasfoundforthefirsttimethatt

5、henon—dissociativemolecularadsorptionofCH3SHontheCu(111)surfacewiththeSatomsittingonthetopsitebelongstotheweakchemisorption，andtheadsorptionenergyis0．39eV．AfterthedissociationoftheS—Hbond．theSatomisIocatedatthebridgesite．withasmallshifttowardthehollowsite．Thedissociativeadsorptionstructureisth

6、ermodynamicallymorestablethantheintactone．andtheadsorptionenergyis0．75-0．77eV．TworeactionpathwayshavebeenstudiedforthetransitionfrOmnon—dissociativeadsorptiontodissociativeadsorption．andtheactivationenergybarrieralongtheminimumenergypathis0．57eV．Theresultsofthecalculationsindicatedthattherelea

7、sedHatompreferstoformabondwiththecoppersurface．ratherthandesorbingintheH2molecularform．ComparingthelocaldensityofstatesofSatomsinthesingleCH3SH，CH3SH／Cu(111)，andCH3S／Cu(111)structures，wefolundthatthebondingbetweentheSatomsandthesubstrat