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1、高壓下LaB6的彈性和熱力學(xué)性質(zhì)的第一性原理計(jì)算(英文)何熹傅敏于白茹川大學(xué)物理科學(xué)與技術(shù)學(xué)院四川大學(xué)原子與分子物理研究所運(yùn)用平面波贗勢(shì)密度泛函理論,研宄了CsCl結(jié)構(gòu)的1^86在高壓下的彈性和熱力學(xué)性質(zhì).計(jì)算中使用了廣義梯度近似,得到在零溫零壓下LaB6的晶格常數(shù)和已知的實(shí)驗(yàn)及其它理論結(jié)果相符.同吋,我們還得到了LaB6的彈性常數(shù)Cij,體彈模量B,剪切模量G,楊氏模量E,德拜溫度€)E,泊松系數(shù)o,壓縮波速VL和剪切波速VS與壓強(qiáng)的關(guān)系.計(jì)算發(fā)現(xiàn)LaB6在壓強(qiáng)低于14GPa時(shí)具有力學(xué)穩(wěn)定性.根據(jù)準(zhǔn)諧徳拜模型,我們還預(yù)測(cè)了CsCl結(jié)構(gòu)1^1%的熱力學(xué)性
2、質(zhì),對(duì)0'4GPa和0l500K范圍內(nèi)熱膨脹系數(shù)和比熱容的變化進(jìn)行了研究.最后分析了1^86在零溫零壓和高壓下的電子態(tài)密度圖.關(guān)鍵詞:密度泛函理論;彈性性質(zhì);電子性質(zhì);熱力學(xué)性質(zhì);:何熹(1992-),男,主要研究領(lǐng)域是第一性原理計(jì)算.作白茹.E-mail:yubrscu@126.com:2017-10-19基金:國家自然科學(xué)基金(11204192)ElasticandthermodynamicpropertiesofLaB6underpressure:afirst-principlesstudyHEXiFUMinYUBai-RuCollegeofPhy
3、sicalScienceandjechnology,SichuanUniversity;InstituteofAtomicandMolecularPhysics,SichuanUniversity;Abstract:TheelasticandthermodynamicpropertiesofCsCl-typestructureLaB6underhighpressureareinvestigatedbyfirst-principlescalculationsbasedonplane-wavepseudopotentialdensityfunctionalt
4、heorymethodwithinthegeneralizedgradientapproximation(GGA).ThecalculatedlatticeparametersofLaBfiunderzeropressureandzerotemperatureareingoodagreementwiththeexistingexperimentaldataandothertheoreticaldata.Thepressuredependencesoftheelasticconstants,bulkmodulusB(GPa),shearmodulusG,Y
5、oung’smodulusE,clasticDebyetemperatureE,Poissonratioo,compressionalwavevelocityVLandshearwavevelocityVSarealsopresented.AnanalysisforthecalculatedelasticconstantshasbeenmadetorevealthemechanicalstabilityofLaBfiupto14GPa.ThethermodynamicpropertiesoftheCsCl_typestructureLaB6arepred
6、ictedusingthequasi-harmonicDebyemodel.ThevariationsofthermalexpansioncoefficientuandthespecificheatcapacityCvareobtainedsystematicallyintherangesof0*4GPaand0'500K.Atlast,thepressuredependencesofthedensityofstatesarealsoinvestigated.Keyword:Densityfunctionaltheory;Elasticpropertie
7、s;Electronicproperties;Thermodynamicproperties;Received:2017-10-191IntroductionTherare-earthhexaboridesRB(ihaveattractedextensiveexperimentalandtheoreticalinterestduetotheirintriguingphysicalproperties.Forexample,CeB6isadenseKondocompoundandhasinterestinglow-temperaturemagneticph
8、ases[1].SmB6isalsoanexemplaryKondoinsula