分子振动的非谐性,振动模间的耦合及多参考效应对速率常数的影响
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- 英文论文题名：The effects of vibrational anharmonicity, mode coupling and electronic multi-reference on reaction rate constants
- 论文作者：马永涛 ; 李辉
- 英文论文作者：Yong-Tao Ma ; Hui Li ; Institute of Theoretical Chemistry ; Jilin University
- 年：2016
- 作者机构：吉林大学理论化学研究所;
- 论文关键词：过渡态理论 ; 非谐性 ; 多参考效应 ; 甲酰自由基
- 会议召开时间：2016-07-01
- 会议录名称：中国化学会第30届学术年会摘要集-第四十六分会：燃烧化学
- 语种：中文
- 分类号：O643.11
- 学会代码：ZGHY
- 会议名称：中国化学会第30届学术年会-第四十六分会 ; 燃烧化学
- 会议地点：中国辽宁大连
- 主办单位：中国化学会
- 学会名称：中国化学会
- 页数：1
- 文件大小：164k
- 原文格式：D
- 会议级别：全国
摘要
目前,有两类方法理论预测反应速率常数,其一是通过体系势能面关键点来推导动力学参数的统计力学方法,另一类是基于含时动力学计算的方法。[1]目前被广泛应用的过渡态理论属于统计力学方法,其优点在于满足了时间和精度双方面的需要.在具体运用过渡态进行计算时,获得反应物和过渡态准确的配分函数对计算结果起着至关重要的作用.当然,要想获得准确的配分函数,需要知道过渡态和反应物的结构,能量及分子振动转动等光谱性质。由于人们研究的基元反应多涉及自由基,反应的过渡态是一个化学键接近形成或断裂的非稳定构型,这样体系的多参考效应显著。在这种情况下,用单参考还是多参考方法优化构型计算体系能量直接关系到计算结果的正确与否。传统的过渡态理论在计算分子的振转配分函数时多用的是刚性转子和谐振子模型,而过渡态和反应物振动的非谐性,扭转及不同振动模间的耦合对配分函数大小产生影响,从而关系到反应速率常数,这也是当前研究的热点和难点。本工作以燃烧中重要的甲酰基自由基氧化反应HCO+O_2→HO_2+CO为例,[2,3]对上述问题进行了研究。
There are two main approaches in the theoretical prediction of the reaction rate constants. One is a statistical approach, which typically derives kinetic parameters from the characterization of the critical points on the potential energy surface, and the other one is based on time-dependent dynamical calculations. The transition state theory is a most widely used statistical approach, which compromises the efficiency and accuracy in determining the reaction rate constants. The accuracy of the calculated rate constant depends entirely on the accuracy of the activation energies and partition functions. However, the vibrational anharmonicities and mode couplings are very important in the computation of the partition functions, and electronic multi-reference character also plays an important role in the calculation of activation energies, especially for addition of O_2 on an radical, or hemolytic dissociation of a single bond forming two radical products. In this work, all of the effects are examined by the case study of HCO+O_2→HO_2+COreaction.
There are two main approaches in the theoretical prediction of the reaction rate constants. One is a statistical approach, which typically derives kinetic parameters from the characterization of the critical points on the potential energy surface, and the other one is based on time-dependent dynamical calculations. The transition state theory is a most widely used statistical approach, which compromises the efficiency and accuracy in determining the reaction rate constants. The accuracy of the calculated rate constant depends entirely on the accuracy of the activation energies and partition functions. However, the vibrational anharmonicities and mode couplings are very important in the computation of the partition functions, and electronic multi-reference character also plays an important role in the calculation of activation energies, especially for addition of O_2 on an radical, or hemolytic dissociation of a single bond forming two radical products. In this work, all of the effects are examined by the case study of HCO+O_2→HO_2+COreaction.
引文
[1]Luc Vereecken;David R.Glowacki;Michael J.Pilling.Chem.Rev.2015,115:4063.
[2]Monica Martinez-Avila;Julio Peiro-Garcia;et al.Chem.Phys.Lett.2003,370:313.
[3]C.-C.Hsu;A.M.Mebel;M.C.Lin.J Chem.Phys.1996,105:2346.
[2]Monica Martinez-Avila;Julio Peiro-Garcia;et al.Chem.Phys.Lett.2003,370:313.
[3]C.-C.Hsu;A.M.Mebel;M.C.Lin.J Chem.Phys.1996,105:2346.