全国功能材料量子设计和量子物理研究生培训

1、Materials Modeling and Simulation from the atomic to the mesoscopic scalesFeng LiuDepartment of Materials Science and EngineeringUniversity of Utah,Salt Lake City,UT编辑课件Overview of Computational Materials ScienceFirst-principles(ab initio)Method basic concepts and approximations parallel implementation edge dislocation in SiMolecular Dynamics Simulation carbon nanotubesMesoscopic Simulation self-assembly/self-organization of quantum dots quantum wiresOutline编辑课件Experiment-Theory-ComputationTheor

2、yNewtonian mechanicsStatistical mechanicsQuantum mechanicsComputationnanoscopicAtomisticElectronicExperiment编辑课件Advance of Computer Power(From F.F.Abraham)编辑课件MissionTo explore the various materials propertiesby computational modeling and simulationPhysical model+algorithmmaterialsproperties编辑课件ObjectiveNot only to elucidate existing experimentalresults but also to predict new materials and novel materials properties to beexplored by experimentsETC编辑课件Self-assembly and self-organization of Nanos

3、tructures(quantum dots and quantum wires)Nanofabrication:Mechanical properties of nanoscale thin filmsand of carbon nanotubesNanomechanics/nanomechanical architecture:Computational designing of nanoscale thin-film andCNT devices(sensors,switches,)Nanoelectronics:First-principles simulation of AFM and STM imagingNanoimaging:Nanocluster engineering of catalytic surfacesNanocatalysis:Current&Near-Future Research Topics编辑课件Computational Software(theory/modeling/simulation packages)First-principles a

4、nd empirical electronic and atomicsimulations of structural,dynamic,mechanical,electronic,transport and magnetic properties ofnanomaterials and nanodevices Nanoscopic simulations of growth and formation ofthin films and nanostructures and self-assembly/self-organization of quantum wires and quantum dots Analytical theory and continuum model ofnanostructures and nanomechanics 编辑课件Computational Hardware(in-house Beowulf clusters)I/ORouterSimple-Construction-Cost-effective-Expandable编辑课件VISCO Compu

5、tational Interface(Visual Interactive Scientific computing)VISCOWeb-BasedvisualizationinterfacecomputingResearch/Education Applications:Provide a web-based visual and interactiveplatform for computationProvide a computational server for a broadrange of users,(experts or non-experts)Go science,engineering,and beyond编辑课件Simulation at Different Length ScalesE=E(Ri)fi=dE/dRi(short-range)Equation of motionof atomsRiAtomicE=E(Li)fi=dE/dLi(long-range)Equation of motionof boundariesLiMesoscopic编辑课件Compl

6、exities of Interatomic PotentialsAb Initio(First-principles)Methods:Etot=Eele-ele+Eele-ion+Eion-ionInput:atomic speciesSemi-Empirical(Classical)Methods:Etot=V2(R1-R2)+V3(R1,R2,R3)+Input:potential parameters编辑课件Comparison of Atomic Simulation Methodsmethodab initioempiricalmechanicsquantumclassicalelectronic effectyesno/approximate accuracygoodfairefficiencyfairgood(system size)(10-103)(102-108)编辑课件Simulation of Materials PropertiesEnergetics:cohesive energy,bonding energy.Structural Properties:c

7、rystal structure,bonding configuration.Elastic Properties:modulus,elastic constants,strain distribution.Electronic Properties:band structure,charge density Dynamic Properties:lattice dynamics,phase transition.编辑课件Simulation of Different Materials SystemsPoint and Extended DefectsThin Films,Surfaces,and InterfacesMolecules and ClustersBulk Materials编辑课件Combine Simulations at Different Length ScalesThermodynamicSimulationKineticSimulationMechanicalSimulationAb InitioBondingEnergies DiffusionBarrie

8、rsElasticConstants编辑课件Multiscale SimulationContinuumClassicalAb inito编辑课件 Edge Dislocations in SiA large-Scale Ab Initio Atomic Simulation by parallel computing编辑课件Pseudopotential Total-Energy MethodDensity Functional Theory:model electron-electron interactionPseudopotential Theory:model electron-ion interactionSupercell Technique:model systems with aperiodic geometryIterative Minimization Technique:optimize electronic coordinates!Parallel Implementation!编辑课件Density Functional TheoryInteracting

9、many-electron problemSingle electron inan effective potential1.Hohenberg P.and Kohn W.,Phy.Rev.136,864B(1964).2.Kohn W.and Sham L.J.,Phy.Rev.140,1133A(1965)Kohn-Sham Equation:Local density approximation:Structural parameters:a tenth of an Total energy difference:a few percentCohesive energy:10%编辑课件Supercell TechniquePeriodic boundaryconditionPlane-wave basisexpansion编辑课件All electronValence electronStrong ionic potentialWeak pseudopotentialPseudopotential TheoryrpsVpsyaeyrZ编辑课件Matrix diagonalizat

10、ion cpu Np3Iterative MinimizationConventional approach:1.Car R.and Parrinello M.,Phy.Rev.Lett.55,2471(1985)Matrix multiplication cpu Nb2NpIterative approach:编辑课件Parallel ImplementationPlane-wave representation:1.Clarke,Stich,and Payne,Comp.Phys.Comm.72,14(1992)Distributing the complex array:编辑课件Computational Technical DetailsLocal Density Approximation:Ceperley-Alder form for exchange and correlationPseudopotential:Kerkers norm-conserving pseudopotential Supercell:Plane-wave energy cutoff of 8 r

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