考虑溶剂效应的荧光计算01.docx

带有溶剂效应的荧光发射光谱计算Step 1: Ground state geometry optimization and frequencies (equilibrium solvation平衡溶剂化：在电子结构不发生改变时，若分子几何结构发生变化则溶剂也跟着变化).This is a standardOpt Freqcalculation on the ground state including PCM equilibrium solvation.获得带有溶剂效应的基态稳定几何结构%chk=01-ac# B3LYP/6-31+G(d,p) Opt Freq SCRF=(Solvent=Ethanol) Acetaldehyde ground state0 1分子说明自行补充Here is the energy of the ground state optimized geometry in solution:SCF Done: E(RB3LYP) = -153.851761719 A.U. after 1 cyclesStep 2: Vertical excitation with linear response solvation.This is a TD-DFT calculation of the vertical excitation, therefore at the ground state equilibrium geometry, with the default solvation: linear response, non-equilibrium. We perform a single-point TD-DFT calculation, which defaults to non-equilibrium solvation. The results of this job will be used to identify which state or states are of interest and their ordering. These results give a reasonable description of the solvation of the excited state, but not quite as good as that from a state-specific solvation calculation. In this case, we see that the n* state(产生第一激发态的跃迁方式) is the first excited state. Next, we will use the state-specific method to produce a better description of the vertical excitation step.复制以上step1中的01-ac.chk,并将复制文件命名为02-ac.chk，然后执行如下操作计算紫外跃迁吸收光谱。下边这个计算默认为non-equilibrium solvation。垂直激发默认为NonEq过程，但此时没有使用EI，表示并未调整激发态结构的electron density使其自洽于环境(几何结构与step4的终态几何结构全同)。%chk=02-ac# B3LYP/6-31+G(d,p) TD=NStates=6 SCRF=(Solvent=Ethanol) Geom=Check Guess=ReadAcetaldehyde: linear response vertical excited states0 1The vertical excitation (absorption) to first excited state from the non-equilibrium solvation linear response calculation: 发生电子跃迁时，溶剂来不及运动，所以叫做non-equilibrium solvation linear responseExcited State 1: Singlet-A 4.3767 eV 283.28 nm f=0.0000 =0.000 Thus, the ground state to first excited state absorption is at 283.28 nm, computed via the linear-response approach.Step 4: Relaxation of the excited state geometry.Next, we perform a TD-DFT geometry optimization, with equilibrium, linear response solvation(在第一激发态的垂直结构基础上进行结构弛豫，此过程不发生电子跃迁，溶剂也跟着调整，所以为equilibrium过程), in order to find the minimum energy point on the excited state potential energy surface. Since this is a TD-DFT optimization, the program defaults to equilibrium solvation. As is typical of such cases, the molecule has a plane of symmetry in the ground state but the symmetry is broken in the excited state, so the ground state geometry is perturbed slightly to break symmetry at the start of the optimization. We retrieve the geometry and other data from the checkpoint file from Step 2:复制02-ac.chk文件，并将复制后文件命名为04-ac.chk.执行如下计算。计算过程中，调整4 1 2 3二面角为10.0的原因是希望分子第一激发态构型脱离平面构型。若不调整这个角度，得到的第一激发态稳定构型将会是平面构型，但在step5中对第一激发态稳定构型进行频率确认的时候，会发现它具有虚频。具有虚频的构型不是稳定构型，因此需要在这一步先把结构调整为非平面构型。(2015年6月12日执行到此步骤后不能获得稳定的激发态结构，陷入循环)。陷入循环的原因是，激发态优化过程中能量发生震荡。Step4是对第一激发态的结构极性弛豫，找到其稳定点。自然状态下，第一激发态会先弛豫到自己的稳定点。%chk=04-ac# B3LYP/6-31+G(d,p) TD=(Read,NStates=6,Root=1) SCRF=(Solvent=Ethanol) Geom=Modify Guess=Read Opt=ReadFCAcetaldehyde: excited state opt Modify geometry to break Cs symmetry since first excited state is A0 14 1 2 3 10.05 1 2 7 -50.0Here are the results for the first excited state after the geometry optimization of first excited state in solution (equilibrium geometry):Excited State 1: Singlet-A 3.2074 eV 386.55 nm f=0.0013 =0.000 12 - 13 0.70615 This state for optimization and/or second-order correction. Total Energy, E(TD-HF/TD-KS) = -153.705918726Step 5: Vibrational frequencies of the excited state structure.Now we run a frequency calculation to verify that the geometry located in step 4 is a minimum. The results could also be used as part of a Franck-Condon calculation if desired (see below). This is a numerical frequency calculation.复制04-ac.chk文件，并将其命名为05-ac.chk,执行如下计算。Root=1表示针对第一激发态结构进行频率计算%chk=05-ac# B3LYP/6-31+G(d,p) TD=(Read,NStates=6,Root=1) Freq SCRF=(Solvent=Ethanol) Geom=Check Guess=Read Acetaldehyde excited state freq0 1The frequency calculation is used to confirm that the geometry optimized in Step 4 is a minimum on the excited state potential energy surface.Step 6: Emission state-specific solvation (part 1).This step does state-specific equilibrium solvation of the excited state at its equilibrium geometry, writing out the solvation data for the next step via the PCMNonEq=writeinput.针对特定的第一激发态的弛豫后结构，考虑Eq 情况下的solvation效应，并将这个效应写入到chk中。此时的Eq情形下数据将会被保留，作为下一次NonEq情形下的溶剂环境数据(当达到激发态relaxed结构时的确是Eq的，但发射荧光后，此时溶剂环境并未改变，而电子结构却改变了，所以发射荧光后溶质感受到的环境是NonEq的：即为writing out the solvation data for the next step via the PCMNonEq=writeinput)。在step4优化所得稳定结构的基础上，加入了SCRF=EI关键词。是调整了溶剂的electron density,使其自洽于环境。可以检测step4的能量与step6的能量的差别，会发现：由于上次计算时step4无法完成，所以还不知道能量差别多大，或是没有差别！复制05-ac.chk文件，并将其命名为06-ac.chk,执行如下计算%chk=06-ac#P B3LYP/6-31+G(d,p) SCRF=(Solvent=Ethanol,ExternalIteration,Read) TD=(Read,NStates=6,Root=1) Geom=Check Guess=Read Acetaldehyde emission state-specific solvation at first excited state optimized geometry0 1NonEq=writeHere is the energy of first excited stateat its optimized geometryfrom the equilibrium solvation state-specific calculation:After PCM corrections, the energy is -153.707148980 a.u.Step 7: Emission to final ground state (part 2).Finally, we compute the ground state energy with non-equibrium solvation(当激发态有弛豫后结构衰变的时候，会发生光谱，即为电子跃迁，溶剂来不及调整，所以默认为non-equilibrium，衰变后，电子结构为基态，但是几何结构依然为激发态弛豫后结构), at the excited state geometry and with the static solvation from the excited state.复制06-ac.chk，并将其命名为07-ac.chk，执行如下特殊几何结构的电子基态结构的计算%chk=07-ac# B3LYP/6-31+G(d,p) SCRF=(Solvent=Ethanol,Read) Geom=Check Guess=ReadAcetaldehyde: ground state non-equilibriumat excited state geometry.0 1NonEq=readHere is the energy of ground state from a non-equilibrium solvation calculation in solution, using the first excited state optimized geometry and the solvent reaction field in equilibrium with the first excited state density):SCF Done: E(RB3LYP) = -153.822024722 A.U. after 10 cycles The difference between the energies from steps 6 and 7 gives the vertical emission energy(即为荧光). In this case, the first excited state to