尋找過渡態(tài)的方法(ts qst2 qst3)

化學(xué)反應(yīng)DA化學(xué)反應(yīng)DA反應(yīng)作為例子簡(jiǎn)單說下我用gaussian找過渡態(tài)的經(jīng)驗(yàn)。Gaussian3QST2gaussian手冊(cè)里的說明。TS是進(jìn)行過渡態(tài)而不是局部最小值的優(yōu)化計(jì)算。QST2STQN方法尋找過分子TSQST2合用。QST3是使用STQN方法尋找過渡態(tài)結(jié)構(gòu)。這個(gè)選項(xiàng)需要輸入反應(yīng)物，產(chǎn)物和最初的過渡態(tài)結(jié)構(gòu)，先后由三組連續(xù)的標(biāo)題和分子說明部分定義。注意在這三個(gè)結(jié)構(gòu)中的原子順序必需一致。TSQST3TS、QST2QST3的輸入文件該怎么寫%chk=c2h4_c4h6_ts%nproc=1%mem=200mb#opt=(ts,calcfc)freq=noramanb3lyp/6-31g*TitleCardRequiredTitleCardRequired01C-0.379602001.410261000.50972400H-0.064094001.040254001.48028400H-0.265895002.480672000.40089100C-1.260203000.70558300-0.28508700H-1.846358001.22289600-1.04415700C-1.26023800-0.70552500-0.28508700H-1.84641800-1.22280900-1.04415900C-0.37967300-1.410247000.50972300H-0.06414500-1.040256001.48028200H-0.26601500-2.480663000.40088700C1.456482000.69084700-0.25401700H1.984024001.246920000.51079100H1.292838001.24312300-1.17152100C1.45645300-0.69091000-0.25401800H1.29278400-1.24317800-1.17152200H1.98396500-1.247007000.51079200qst2%chk=c2h4_c4h6_qst2%nproc=1%mem=200mb#opt=(calcfc,qst2)freq=noramanb3lyp/6-31g*TitleCardRequired01C-3.177919061.13289796-1.01187682H-2.644755310.20519304-1.01187682H-4.247919061.13289796-1.01187682C-2.502644752.30787525-1.01187682H-3.035808503.23558018-1.01187682C-0.962644752.30787525-1.01187682H-0.429481003.23558018-1.01187682C-0.280401351.13693077-1.01187682H-0.808043820.20607449-1.01187682H0.789579771.14328807-1.01187682C-2.597764130.988942791.10133233H-3.140310630.066925591.12200992H-3.126998871.918463751.07302387C-1.242608730.983479681.11087410H-0.700062231.905496891.09019651H-0.713373980.053958731.13918256TitleCardRequired01TitleCardRequired01C1.414324000.094601000.31826800H1.423700000.107754001.42899000H2.474456000.127801000.00402400C0.668660001.30146700-0.16992700H1.264389002.14276400-0.50621500C-0.668907001.30134300-0.16992700H-1.264793002.14252900-0.50621700C-1.414346000.094338000.31826600H-1.423727000.107494001.42898900H-2.474484000.127340000.00402000C0.77040400-1.21422100-0.17552700H1.14229400-2.052881000.44176200H1.12544800-1.41421500-1.20543600C-0.77017000-1.21437000-0.17552800H-1.12517200-1.41443600-1.20543700H-1.14189800-2.053102000.44176200qst3%chk=c2h4_c4h6_qst3%chk=c2h4_c4h6_qst3%nproc=1%mem=200mb#opt=(calcall,qst3,noeigentest)freq=noramanb3lyp/6-31g*TitleCardRequiredTitleCardRequired01C-3.177919061.13289796-1.01187682H-2.644755310.20519304-1.01187682H-4.247919061.13289796-1.01187682C-2.502644752.30787525-1.01187682H-3.035808503.23558018-1.01187682C-0.962644752.30787525-1.01187682H-0.429481003.23558018-1.01187682C-0.280401351.13693077-1.01187682H-0.808043820.20607449-1.01187682H0.789579771.14328807-1.01187682C-2.597764130.988942791.10133233H-3.140310630.066925591.12200992H-3.126998871.918463751.07302387C-1.242608730.983479681.11087410H-0.700062231.905496891.09019651H-0.713373980.053958731.13918256TitleCardRequired01TitleCardRequired01TitleCardRequired01TitleCardRequired01C1.414324000.094601000.31826800H1.423700000.107754001.42899000H2.474456000.127801000.00402400C0.668660001.30146700-0.16992700H1.264389002.14276400-0.50621500C-0.668907001.30134300-0.16992700H-1.264793002.14252900-0.50621700C-1.414346000.094338000.31826600H-1.423727000.107494001.42898900H-2.474484000.127340000.00402000C0.77040400-1.21422100-0.17552700H1.14229400-2.052881000.44176200H1.12544800-1.41421500-1.20543600C-0.77017000-1.21437000-0.17552800H-1.12517200-1.41443600-1.20543700H-1.14189800-2.053102000.44176200C0.39335100-1.407522000.50945100H0.07415700-1.040745001.48001500H0.28923500-2.478840000.39989000C1.26702700-0.69422900-0.28512700H1.85846600-1.20567200-1.04409200C1.253468000.71680900-0.28478600H1.834993001.23987800-1.04346600C0.365749001.413091000.50971100H0.054145001.040536001.48056200H0.242487002.482465000.40066900C-1.45041500-0.70335800-0.25427100H-1.97290400-1.264326000.51044000H-1.28115600-1.25385900-1.17177300C-1.462407000.67835900-0.25370700H-1.304679001.23254800-1.17112400這里有一些我個(gè)人用TS的鍵長(zhǎng)延長(zhǎng)5這里有一些我個(gè)人用TS的鍵長(zhǎng)延長(zhǎng)5?；蛘哐娱L(zhǎng)QST3最后一個(gè)構(gòu)型是自己功底。另外使用QST2以及QST3時(shí)要注意你所以我比較推薦直接用TS還是calcall由于這一步直接關(guān)系著整個(gè)體系的計(jì)算量所以需要慎重選擇chk文件進(jìn)行過渡態(tài)優(yōu)化，并且上一個(gè)計(jì)算做了頻率分析，那毫無疑問要加上rcfc，這可以節(jié)省大量的時(shí)間。如果從頭開始找過渡態(tài)的話還是calcfc的好，也就是在第一步計(jì)算下力常數(shù)，至于calcall個(gè)人推薦不到calcall15calcfc47--！Hessian中該坐標(biāo)的行和列計(jì)算數(shù)值二階導(dǎo)數(shù)的方法來獲得過渡態(tài)，示例如下。%chk=c2h4_c4h6_ts_d%mem=200mb%nproc=1#opt=(ts,modredundant)freq=noramanb3lyp/6-31g*TitleCardRequired01C-0.264421000.424036001.41432400H-1.298998000.828422001.42370100H0.041311000.344168002.47445600C0.618365001.380883000.66866500H1.229978002.049311001.26439800C0.618365001.38088300-0.66866500H1.229978002.04931100-1.26439800C-0.264421000.42403600-1.41432400H-1.298998000.82842200-1.42370100H0.041311000.34416800-2.47445600C-0.26442100-1.616745000.77039900H-1.13801600-2.183518001.14228500H0.62859000-2.167419001.12544200C-0.26442100-1.61674500-0.77039900H0.62859000-2.16741900-1.12544200H-1.13801600-2.18351800-1.14228500B814DB111D（maxstep=7oriop(1/8=7）繼續(xù)找過渡態(tài)。如果仍然沒有找到可以對(duì)你猜測(cè)的構(gòu)象進(jìn)行GVmanualdisplacement0.2-0.4或者你不要的虛頻向右調(diào)0.2-0.4以微調(diào)構(gòu)象，SCAN參加反應(yīng)的鍵長(zhǎng)，逐漸拉長(zhǎng)鍵長(zhǎng)然后看能量的變化趨勢(shì)（注意這里只選擇一個(gè)鍵，選取能量的最高點(diǎn)的坐標(biāo)進(jìn)行過渡態(tài)優(yōu)化（見圖示以上能找到過渡態(tài)。如果你仍然找到過渡態(tài)那可以調(diào)整你的初始猜測(cè)構(gòu)象然后重復(fù)以上的步驟。重復(fù)N次后你仍然找不到過渡態(tài)的話請(qǐng)重新思考你所假象的反應(yīng)通道是否正確所有方法都用了還是找不到過渡態(tài)那可以試一下calcall~~如果你還不放心那你可以用SCAN優(yōu)化（這會(huì)消耗大量的機(jī)時(shí)，雖然準(zhǔn)確但絕不推薦，另本文中的勢(shì)能面使用am1做的，僅供參考）……3-21甚至sto-3就可以。如果體系中全部都是前三個(gè)周期的原子那用pm6或am1