从头算分子动力学研究硫脲嘧啶及其互变异构体在低能电子作用下的解离过程  

Ab initio molecular dynamics study on dissociation process of 2-thiouracil and its tautomers under low-energy electron interactions

作　　者：张颖 王兴[2] 徐忠锋[2] 任洁茹[2] 张艳宁 周贤明 梁昌慧 张小安[1,3] Zhang Ying;Wang Xing;Xu Zhong-Feng;Ren Jie-Ru;Zhang Yan-Ning;Zhou Xian-Ming;Liang Chang-Hui;Zhang Xiao-An(College of Physics&Electronic Engineering,Xianyang Normal University,Xianyang 712000,China;School of Physics,Xi’an Jiaotong University,Xi’an 710049,China;Institte of Modern Physics,Chinses Academy of Sciences,Lanzhou 730000,China)

机构地区：[1]咸阳师范学院物理与电子工程学院,咸阳712000 [2]西安交通大学物理学院,西安710049 [3]中国科学院近代物理研究所,兰州730000

出　　处：《物理学报》2024年第2期127-136,共10页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:12205247,12175174);陕西省教育厅科学研究计划(批准号:22JK0604)资助的课题。

摘　　要：运用玻恩-奥本海默分子动力学模型结合密度泛函理论研究了气相下硫脲嘧啶与低能电子吸附解离动力学过程,发现硫脲嘧啶及其互变异构体在吸附解离过程中一个重要的脱氢现象,即特定位置的化学键N—H键,C—H键断裂,使其在N位点和C位点失去氢原子,形成解离过程中最主要的负离子碎片——闭壳层脱氢负离子(TU-H)-为了更深刻地认识脱氢现象,分别对断裂的化学键进行势能曲线扫描,对键解离能、电子亲和能、负离子(TU-H)-出现势进行计算对比发现,在所有断裂的化学键中N—H键最容易发生断裂,而负离子(TU-H)-的形成主要源于N—H键的断裂.When biomolecules interact with high-energy particles and rays,they are directly ionized or dissociated,then a large number of low-energy electrons are formed as secondary particles.These low-energy electrons will attach to biomolecules,and trigger off the secondary dissociation,forming free radicals and ions with high reactivity,which can damage the structure and function of the biomolecule and cause irreversible radiation damage to the biomolecule.It is important to study the low-energy dissociative electron attachment(DEA)process of biomolecules for understanding radiation damage to biological organisms.Currently,the theoretical studies of DEA have mainly focused on the bound states of negative ions and the types of resonances in the dissociation process.The dissociation process is well described by quantum computational method,but the diversity and complexity of dissociation channels present in the dissociation process of 2-thiouracil molecule also pose a great computational challenge to these methods.In addition,the quantum computational methods are not ideal for dealing with the discrete states of chemical bonds and the problem of continuity coupling of electrons.The dissociation dynamics of biomolecules mainly results from ionization and electron attachment.Ab initio molecular dynamics simulation can reasonably describe these processes.In light of these considerations,ab initio molecular dynamics simulation is used in this work to study dynamic variation process in DEA.The lowenergy electron dissociative attachment to 2-thiouracil in the gas phase is studied by using the Born-Oppenheimer molecular dynamics model combined with density functional theory.It is found that an important dehydrogenation phenomenon of 2-thiouracil and its tautomers occurs in the DEA process,and that the N—H and C—H bond are broken at specific locations.Due to the loss of hydrogen atoms at the N and C sites,the closed-shell dehydrogenated negative ion(TU-H)-forms,which is the most important negative ion fragments in the dissoci

关 键 词：玻恩-奥本海默分子动力学 密度泛函理论 电子吸附解离 硫脲嘧啶 

分 类 号：O626[理学—有机化学]