堆积的胸腺嘧啶体系光物理失活的动力学模拟.pdf

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1、物理化学学~(WuliHuaxueXuebao1NovemberActa尸．一Chim．Sin．2011，27(11)，2559-25642559[Article]www．whxb．pku．edu．cn堆积的胸腺嘧啶体系光物理失活的动力学模拟豆育升李伟袁帅张文英李安阳舒坤贤唐红(重庆邮电大学高性能计算与应用研究所，重庆400065)摘要：采用半经典动力学方法模拟了丌堆积的胸腺嘧啶体系最低激发态的光物理失活过程．设置激光脉冲仅作用于一个胸腺嘧啶分子另一胸腺嘧啶分子T保持基态．模拟发现由于T与T之间存在

2、丌士I}积相互作用．导致电荷转移，形成T带负电荷、T带正电荷的激基复合物．由于相邻分子的空间效应阻碍了激发的T分子到达圆锥相交所必需的强烈扭曲，激基复合物的寿命比单体增长．当分子间距离缩短至0．3nm后，T分子C一C。键扭曲程度最大，此时发生电荷重组，两个胸腺嘧啶分子均恢复电中性．电荷重组诱导Tr分子发生畸变，并在C5'一C。扭曲最大时避免相交，体系衰减至基态，T和T分子均恢复平面构型．关键词：胸腺嘧啶：半经典动力学模拟：电荷转移：激基复合物：失活中图分类号：O641：0644DynamicsSim

3、ulationofPhotophysiCaIDeactivationPathwayforStackedThyminesDOUYu-ShengLIWeiYUANShuaiZHANGWen—YingLIAn-YangSHUKun—XianTANGHong(InstituteofHighPerformanceComputingandApplication，ResearchCenterofNetworkandComputin~ChongqingUniversityofPostsandTelecommunic

4、ations，Chongqing400065，PR．China)Abstract：AsemiclassicaldynamicssimulationstudywasundertakentodeterminethephotophysicaldeactivationoftheIowestexcitedstateoftwostackedthymines．Onlyonethymine．referredtoaswasexcitedbyalaserpulseandtheothermolecule．referred

5、toasT．remainedjnthegroundstate．ThesimulationresultsshowthatchargetransferbetweenthetwothyminesbecauseofaE-stackinginteractionleadstotheformationofanexcimerstate。whichincludesanegativeTandapositiveT．Additionally,lhesimulationstudyindicatesthatastericeff

6、ectoftheneighboringbasesinhibitstheout．of-planedeformation．whichiSessentiaIinaccessingtheconicaIintersectionbetweenthelowestelectronic．excitedstateandthegroundstate．ThestericefecteventuallyleadstoaIongerelectronic．excitedstateIifetimeforthetwostackedth

7、ymines．ThesimulationresultsrevealthatwhentheinterbasedistanceiSIessthan0．3nmthemoleculeThasaremarkabledeformationatitsC5andC6sitesresultinginchargerecombination．ThechargerecombinationultimatelymakesthesystemelectronicallyneutraI．Ontheotherhand．themolec

8、uleThasastrongtwistaboutitsC5一C6bondintheproximityoftheavoidedcrossingbywhichthesystemdecaystothegroundstate．Finally,thetwothyminemoleculesintheirgroundstatesrecovertheirplanargeometries．KeyWords：Thymine；Semiclassicaldynamicsimulation；C