2016燃烧学年会集文献

230026；3南京大学化学化工学院，南京，210023） Email:摘要生物柴油燃烧反应的理论研究得到了广泛的关注，然而庞大的计算量限制了传统的高精度量GEBFLSQCCnH2n+1COOCH3（n=4,5）的脱氢反应在QCISD(T)/CBS理论水平下进行了计算。结果表明，GEBF方法可以在保证能垒的绝对误差小于0.1kcal/mol同时大大的缩减计算时间。关键词生物柴油；脱氢反应；GEBF方法；LSQCCCSD(T)CBS基组计算得到的反应能垒和QCISD(T)CBS1.0kcal/mol以内，反0.6kcal/mol以内[6]10个要分为两类：局域相关方法[8,11,14-18]和分片方法[19-29]。其中分片方法的主要思想是将大basedfragmentation,GEBF)方法[283034]的高效性和精确性已在各种大分子体系，如生物相关方法，如MP2，CCSD，CCSD(T)等）方法[31]进一步地提高了计算精度。本文中，我们通过GEBF-X/HF方法将QCISD(T)/CBS方法应用到燃烧化学的计算中。燃烧化学的计算很多涉及自由基的反应，但是GEBF方法未曾应用到开壳层分子的QCISD(T)/HFCBS基组)能量来验证和确定GEBF方法中相关参数的设置。然后我们CnH2n+1COOCH3(n=4,5)（见图1）被氢原子提取一个氢生成氢气的反应。计算中得到的GEBF-QCISD(T)/HF(CBS基组)能量与传统的QCISD(T)/CBS能量进行对比，验证GEBF1CnH2n+1COOCH3H(n=4,5)CnH2n+1COOCH3(N=6,7,8)的结构优化和频率计算用的是密度泛函方法M06-2X/6-311++g(d,p)，该方法兼顾计算效率和计算精度，在燃烧化学计算中广泛应用[40,41]0.97[42,43]。GEBF方=E[QCISD(T)/CBS]DZ→TZ+{E[MP2⁄CBS]TZ→QZ-GEBF方法是通过将大分子划分成小的碎片，再根据每个碎片临近的碎片结构将该我们以C6H13COOCH3为例介绍GEBF方法的具体实现过程。F4出现。每个片段的大小非氢原子构成一个片段。于是得到划分的片段F1~F5。ζ距离内的片段都将连接到该中心片段上，同时F3Sys2F4Sys3，以F5Sysy。需要注意的是，如果一个初始子体系完全被另一个初始子体系11次该子体系的能量，系数为-1则表示减去一次该子体系的能量。其中最大的子体系中的片段数目是nmax=3。1mm=nmax-1m个片F1F2mm=nmax-22,1)片段的子体系重复上述构建派生子体系的过程，对刚刚构建的初始和派生子体系Sys1~Sys51m片段子Energy112131456171819245ξ~ξ2之间的片段之间的相互作用则没有被考H原子，因此包含了开壳层H提取反应的过渡态，反应涉及到的两个H原子由于距离分子主要片段较远，将会被划分到一个单独的片段中，如图3中所示的F6片段。3C5H11COOCH3+H=C5H10COOCH3+H2 Cm̃ A

F2，F2，F4HF1F5片段里的每个原子被位HF方法计算得到的Mulliken电荷，esp电荷，或者npa电荷等。Cmm个子体系的系数。QAQBAB上的点电荷，RABAB之间在此不赘述，见李等人[28]的文章。C6H13COOCH3带Mulliken背景点电荷的各子体系的CCSD(T)/cc-pVTZ能量，静电相互作用以及得到的最终总能量见表1。HF能量相加得到总的GEBF-X/HF能量，计算公式如下： 其中，EGEBF-XEGEBF-HFGEBFXHF 总能量，EHFGEBF-X/HF对闭壳层分子C4H9COOCH3和C5H11COOCH3，开壳层自由基C4H9COOCH3_PCMe2和C5H11COOCH3_PC4以及过渡态C4H9COOCH3_TSMe2和C5H11COOCH3_TS4QCISD(T)/cc-pVDZ能量计算，其中计算的分子分别是反应C4H9COOCH3+H=C4H9COOCH3_PCMe2+H2和C5H11COOCH3+H=（’PC’22GEBF-GEBF-X/HF方法。(GEBF-X/HF)

(kcal/molGEBF-X/HFXQCISD(T)/cc-pVTZ方法)QCISD(T)/cc-pVTZQCISD(T)/CBS方法里最耗时的方法，基于该方法的计算能Frag1，Frag2，Frag31，2，3个非氢原子。其中只对5C8H17COOCH3体趋势上，可以看出碳链越长的分子越需要大的分片方式使得最终构建的子体系足够接所需要的时间，节省时间的计算方法是：(传统方法的计算时间-GEBF方法的计算时间)/GEBF6。可GEBF计90%以上（Frag1Frag2分片方法）。另外，GEBF的另一个优势[39]是将一个只能在单个节点上计算的分子划分成可以同时在多个节点上并行计算的子体系分子，从而进一步的节省了计算时间。对比三种分片方式，除了C4H9COOCH3，对其他分Frag1分片方式都较Frag2我们将对CnH2n+1COOCH3(n=4,5)+H的反应系统采用Frag1的分片方式。)

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能量误差 节省时间GEBF-X/HFC4H9COOCH3H=C4H9COOCH3_PCnH2(n=Me1,Me2,12,3)C5H11COOCH3+H=C5H11COOCH3_PCn+H2(n=Me1,Me2,1,2,3,4)的势能面。’(GEBF-X/HF)QCISD(T)/cc-pVTZQCISD(T)/CBSGEBF-X/HF能量误差一样大，且都小于其他方法的GEBF-X/HF能量误差。(GEBF能垒误差15.6(-9.9(-16.415.515.310.49.9(-6.913.6(-12.87.513.312.57.115.6(-9.9(-16.3(-15.4(-15.2(-10.3(-9.8(-7.013.9(-13.07.713.312.47.013.612.712.49.1(-8.0(-7.4(-14.2(-15.3(-15.314.3(-15.2(-15.0(-12.913.613.414.916.116.017.117.917.6(-12.313.413.212.413.413.412.8(-13.613.414.2(-15.3(-15.314.2(-15.1(-15.0(-12.9(-13.8(-13.7(-12.7(-13.4(-13.2(-14.816.015.917.017.817.512.113.0(-12.9(-12.613.313.1(-12.812.712.313.012.812.313.313.312.8(-13.513.4GEBF-X/HF的与传统量化方法能垒之间的差值（括’X/HF0.1kcal/mol，且大部分反应的能垒C4H9COOCH3C5H11COOCH3各个H7a7b。由此可以看出，电子相关能的校正和基组的大小对能垒的影响都很大，其中前者的影响更大一些。相对于QCISD(T)方法，MP2QCISD(T)/CBS4kcal/mol以上，尤其是MP2/cc-pVDZQCISD(T)/CBS5.6~6.6kcal/molQCISD(T)配上不同基组的方法之间的差异比较小，QCISD(T)/cc-pVDZ的能垒比QCISD(T)/CBS的高1.0~1.9kcal/mol，QCISD(T)/cc-pVTZ的能垒只比QCISD(T)/CBS0.3~0.6kcal/mol。 为了探究不同燃料分子各个位点H提取反应的关系，我们将C4H9COOCH3和C5H11COOCH3HQCISD(T)/CBS88可以看出，在不同碳链长度的脂肪酸甲酯中，相同类型位点的H提取反应的能垒几乎一致，最2HC4H9COOCH3C5H11COOCH30.22kcal/mol两种类型甲基（Me1Me2）H提取反应能垒是HQCISD(T)方法的差值大很多。从另结GEBF方法在本研究中的应用选取合适的背景点电荷和分片方法。GEBF-X/HF方法的能量精GEBF-X/HF能量的精GEBF方法的计算时间随着分子尺寸几乎线性增长，因此对大分子的高精GEBF-QCISD(T)/HF(CBS基组)QCISD(T)/CBS能量进行0.1kcal/mol以内。GEBF-X/HF0.1kcal/molGEBF方法对开壳层自由基和过渡态分子的适用性以及精确LahaneS,SubramanianKA.Effectofdifferentpercentagesofbiodiesel–dieselblendsoninjection,spray,combustion,performance,andemissioncharacteristicsofadieselengine[J].Fuel.2015,139:537--545.ShahirVK,JawaharCP,SureshPR.ComparativestudyofdieselandbiodieselonCIenginewithemphasistoemissions—Areview[J].RenewableandSustainableEnergyReviews.2015,45:686--697.AzjargalJ.TheComparisonofCombustionCharacteristicsandPerformancesofDieselEngineFueledwithBiodieselandDieselBlends[J].The9thInternationalForumonStrategicTechnology.2014.KlippensteinSJ,PandeVS,TruhlarDG.ChemicalKineticsandMechanismsofComplexSystems:APerspectiveonRecentTheoreticalAdvances[J].JournaloftheAmericanChemicalSociety.2014,136(2):528--546.PapajakE,TruhlarDG.Whatarethemostefficientbasissetstrategiesforcorrelatedwavefunctioncalculationsofreactionenergiesandbarrierheights?[J].TheJournalofChemicalPhysics.2012,137(6):ZhangP,KlippensteinSJ,LawCK.AbInitioKineticsfortheDecompositionofHydroxybutylandButoxyRadicalsofn-Butanol[J].TheJournalofPhysicalChemistryA.2013,117(9):1890--1906.SubotnikJE,SodtA,Head-GordonM.Anearlinear-scalingsmoothlocalcoupledclusteralgorithmforelectronicstructure[J].TheJournalofChemicalPhysics.2006,125(7):74116.NakaoY,HiraoK.Alocalsecond-orderMøller–Plessetmethodwithlocalizedorbitals:Aparallelizedefficientelectroncorrelationmethod[J].TheJournalofChemicalPhysics.2004,120(14):6375.ScuseriaGE.LinearScalingDensityFunctionalCalculationswithGaussianOrbitals[J].TheJournalofPhysicalChemistryA.1999,103(25):4782--4790.MillamJM,ScuseriaGE.Linearscalingconjugategradientdensitymatrixsearchasanalternativetodiagonalizationforfirstprincipleselectronicstructurecalculations[J].TheJournalofChemicalPhysics.1997,106(13):5569.HampelC,WernerH.Localtreatmentofelectroncorrelationincoupledclustertheory[J].TheJournalofChemicalPhysics.1996,104(16):6286.LiX,NunesRW,VanderbiltD.Density-matrixelectronic-structuremethodwithlinearsystem-sizescaling.[J].PhysicalReviewBCondensedMatter.1993.Zhang,L.andZhangP.Towardshigh-leveltheoreticalstudiesoflargebiodieselmolecules:anONIOM[QCISD(T)/CBS:DFT]studyofhydrogenabstractionreactionsofCnH2n+1COOCmH2m+1+H.PhysicalChemistryChemicalPhysics.2015.17(1):200-208.FriedrichJ,HanrathM,DolgM.Fullyautomatedimplementationoftheincrementalscheme:ApplicationtoCCSDenergiesforhydrocarbonsandtransitionmetalcompounds[J].TheJournalofChemicalPhysics.2007,126(15):154110.LiS,MaJ,JiangY.Linearscalinglocalcorrelationapproachforsolvingthecoupledclusterequationsoflargesystems[J].JournalofComputationalChemistry.2002,23(2):237--244.44:213--236.LiW,PiecuchP.MultilevelExtensionoftheCluster-in-MoleculeLocalCorrelationMethodology:A.2010,114(24):6721--MaslenPE,Head-GordonM.Non-iterativelocalsecondorderMoller-Plessettheory[J].ChemicalPhysicsLetters.1998,283(1-2):102--108.NagataT,FedorovDG,KitauraK,etal.Acombinedeffectivefragmentpotential–fragmentmolecular131(2):24101.KobayashiM,ImamuraY,NakaiH.Alternativelinear-scalingmethodologyforthesecond-orderMoller-Plessetperturbationcalculationbasedonthedivide-and-conquermethod[J].TheJournalofChemicalPhysics.2007,127(7):FedorovDG,KitauraK.Coupled-clustertheorybaseduponthefragmentmolecular-orbitalmethod[J].TheJournalofChemicalPhysics.2005,123(13):134103.Physics.2009,131(11):114108.DahlkeEE,TruhlarDG.ElectrostaticallyEmbeddedMany-BodyCorrelationEnergy,withApplicationsClusters[J].JournalofChemicalTheoryandComputation.2007,3(4):1342--1348.DahlkeEE,TruhlarDG.ElectrostaticallyEmbeddedMany-BodyExpansionforLargeSystems,withApplicationstoWaterClusters[J].JournalofChemicalTheoryandComputation.2007,3(1):46--53.HirataS,ValievM,DupuisM,etal.Fastelectroncorrelationmethodsformolecularclustersinthegroundandexcitedstates[J].MolecularPhysics.2005.FedorovDG,KitauraK.SecondorderMøller-Plessetperturbationtheorybaseduponthefragmentmolecularorbitalmethod[J].TheJournalofChemicalPhysics.2004,121(6):2483.GordonMS,FedorovDG,PruittSR,etal.FragmentationMethods:ARoutetoAccurateCalculationsonLargeSystems[J].ChemicalReviews.2012,112(1):632--672.LiW,LiS,JiangY.GeneralizedEnergy-BasedFragmentationApproachforComputingtheGround-State-LiS,LiW,FangT.AnEfficientFragment-BasedApproachforPredictingtheGround-StateEnergiesandStructuresofLargeMolecules[J].JournaloftheAmericanChemicalSociety.2005,127(19):7215--7226. 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