幻灯片10Simulation(modeling/computation/theory)andexperimentCalaskarching for wy keys.Because thelight here is somuchbetter!理论与现实的差距上一页Warshel的例子是计算模拟的人们内部的纷争，实验对做理论计算的人的看法又是什么？Thedrunken man searchingfor hiskeys (solution):Aawkward situation ofcomputation/simulation/theory people in thereal world (experimentalproblems);Agap between reality (bar)andtheory (street lamp)
幻灯片 10 Simulation (modeling/computation/theory) and experiment 10 Because the light here is so much better! 理论与现实的差距 上一页Warshel的例子是计算模拟的人们内部的纷争，实验对做理论计算的人的 看法又是什么？ • The drunken man searching for his keys (solution): A awkward situation of computation/simulation/theory people in the real world (experimental problems); • A gap between reality (bar) and theory (street lamp)
幻灯片11ModelModel:An encapsulated"black-box" can predict properties.Given necessary input, itautomatically provides relevantoutput;Build a model:·SimplificationisthekeyUseamodel:·Information lost inevitable;?Attitude: principles (the more the- Must find descriptors;better)andlimitations(mustknow);·Mechanismforautomation:?Levels ofmodeling:a)take-then-use,input->output (qualitativeb)minor adjustments, c) majorand quantitative);modification,d)build new models.Understandyour model&system:·Abletopredict:directionofmisuse&abusing modelssystems'evolution关于模型1、模型的特征是Encapsulation【封装】或者说self-contained【完备的】，atermborrowedfromcomputerscience(object-orientedprogramming)Amodel isclosetowhatanObjectmeansinprogramming:encapsulated,inheritable, overloading/overriding, with private/public variable/methods....2、建立模型【简化是关键！】【代价是信息损失】【描述因子是关键抓手】【建立输入输出转换机制】3、使用模型I、Take-&-use:computation/calculation=analysistool(XRD,TEM...);【与使用分析测试仪器一样】adjustment/overhaul:modeling/simulation；【进入建模】buildnewones:modeling/theory【进入理论化学的范畴】Il、misuse&abusingmodels:e.g.B3LYP in excited states forconjugated systems orchargeseparatedsystems（zwitterions)。【流行的不一定是好（对）的】
幻灯片 11 Model 11 Model：An encapsulated ”blackbox” can predict properties. Given necessary input, it automatically provides relevant output; Build a model: • Simplification is the key; • Information lost inevitable; • Must find descriptors; • Mechanism for automation: input-> output (qualitative and quantitative); • Able to predict: direction of systems’ evolution • Attitude: principles (the more the better) and limitations (must know); • Levels of modeling: a) take-then-use, b)minor adjustments, c) major modification, d) build new models: • Understand your model & system: misuse & abusing models Use a model: 关于模型 1、模型的特征是Encapsulation【封装】或者说self-contained【完备的】, a term borrowed from computer science (object-oriented programming). A model is close to what an Object means in programming: encapsulated, inheritable, overloading/overriding, with private/public variable/methods. 2、建立模型 【简化是关键！】 【代价是信息损失】 【描述因子是关键抓手】 【建立输入输出转换机制】 3、使用模型 I、Take-&-use: computation/calculation = analysis tool (XRD, TEM.); 【与使用分 析测试仪器一样】 adjustment/overhaul: modeling/simulation; 【进入建模】 build new ones: modeling/theory【进入理论化学的范畴】 II、misuse & abusing models: e.g. B3LYP in excited states for conjugated systems or charge separated systems (zwitterions)。【流行的不一定是好（对）的】
幻灯片12Models?Modeling (evaluation) is everywhere;·Assess a model:What You KnowvsHow much youknowabout itgood/correct vs.cost-Whnt Youperformanceratio;Doh.? Limit of a model;ALIKALotoeacbrotModels(algorithms)arejustmorequantitativeextrapolationand interpolation of intuitions模拟1、模型即能够将输入信息转变为预测性的输出信息的黑匣子2、模拟无处不在！起床看太阳，判断下雨的几率。输入信息（descriptor）为太阳的亮度，输出下雨的几率。过马路、食堂打饭排队.3、模型的好坏八电子规则【各位已经能够做电子结构的计算了！！！】、共振理论、分子轨道理论、自然键轨道理论：VSEPR【价电子互斥理论】、晶体场、配位场理论；4、模型的局限性滥用模型abusethemodel(Oops!Youovershotit)5、模型（算法）的本质对直觉和已有知识的定量化的【外推和内插】
幻灯片 12 Models 12 • Modeling (evaluation) is everywhere; • Assess a model: good/correct vs. costperformance ratio; • Limit of a model; • Models (algorithms) are just more quantitative extrapolation and interpolation of intuitions 模拟 1、模型即能够将输入信息转变为预测性的输出信息的黑匣子 2、模拟无处不在！ 起床看太阳，判断下雨的几率。输入信息（descriptor）为太阳的亮度，输出下 雨的几率。 过马路、食堂打饭排队.； 3、模型的好坏 八电子规则【各位已经能够做电子结构的计算了！！！】、共振理论、分子轨道理 论、自然键轨道理论；VSEPR【价电子互斥理论】、晶体场、配位场理论； 4、模型的局限性 滥用模型 abuse the model (Oops! You overshot it) 5、模型（算法）的本质 对直觉和已有知识的定量化的【外推和内插】
幻灯片13TopicsnotcoveredWecanmodel everything!6fo电子结构在多尺度模拟中的位置1、跨（多）尺度模拟图；【一切皆可模拟！】横轴尺度纵轴时间2、我们观测或者计算什么？实验上可以观察连续的变化或者关键的稳态：我们讨论的量子化学计算模拟关心电子结构和演化（伪），本质是模拟/获取snapshots;3、化学键实时的变化需要电子动力学：在左下角Lowerleftcorner：Quantumelectrondynamics
幻灯片 13 Topics not covered 13 We can model everything! 电子结构在多尺度模拟中的位置 1、跨（多）尺度模拟图；【一切皆可模拟！】 横轴 尺度 纵轴 时间 2、我们观测或者计算什么？ 实验上可以观察连续的变化或者关键的稳态； 我们讨论的量子化学计算模拟关心电子结构和演化（伪），本质是模拟/获取 snapshots； 3、化学键实时的变化需要电子动力学；在左下角Lower left corner: Quantum electron dynamics
幻灯片14Simulationrelatedconcepts·Theoreticalchemistry.Quantummechanics/classicalmechanicsbasedmodelsforchemicalsystems.Computationalchemistry.Program(algorithm)+chemicalsystems.Quantumchemistry.Chemicalsystemsexplainedbyquantummechanics(throughcomputation).Electronicstructurecalculation.Computationalchemistryfocusedonchemicalbonds (static,formation/cleavage)这些概念没有严格的定义，使用起来主要是看习惯和偏好。【板书：理论化学，计算化学，量子化学，电子结构计算】【跟量子计算不同】Quantumcomputingiscomputingusingquantum-mechanicalphenomena,suchassuperpositionandentanglement.Quantumcomputation uses quantum bits or qubits, n qubits can superpose into 2n states,equal(?)to2^nbit ofmemory.measurement collapses the states intoone
幻灯片 14 1 4 Simulation related concepts • Theoretical chemistry • Quantum mechanics/classical mechanics based models for chemical systems • Computational chemistry • Program (algorithm) + chemical systems • Quantum chemistry • Chemical systems explained by quantum mechanics (through computation) • Electronic structure calculation • Computational chemistry focused on chemical bonds (static, formation/cleavage) 这些概念没有严格的定义，使用起来主要是看习惯和偏好。 【板书：理论化学，计算化学，量子化学，电子结构计算】 【跟量子计算不同】Quantum computing is computing using quantummechanical phenomena, such as superposition and entanglement. Quantum computation uses quantum bits or qubits, n qubits can superpose into 2^n states, equal(?) to 2^n bit of memory. measurement collapses the states into one