高等学校化学学报 ›› 2019, Vol. 40 ›› Issue (8): 1649.doi: 10.7503/cjcu20190254

• 物理化学 • 上一篇    下一篇

范德华复合物Kr-C2H2的势能面和振转光谱的理论研究

白旭, 韩超英, 朱华   

  1. 四川大学化学学院, 成都 610064
  • 收稿日期:2019-05-05 修回日期:2019-07-23 出版日期:2019-08-10 发布日期:2019-07-12
  • 通讯作者: 朱华,女,博士,教授,主要从事分子光谱研究.E-mail:zhuhua@scu.edu.cn E-mail:zhuhua@scu.edu.cn
  • 基金资助:
    国家自然科学基金(批准号:21373139)和四川省应用基础项目(批准号:2018JY0712)资助.

Theoretical Studies of the Potential Energy Surface and Rovibrational Spectra for Kr-C2H2

BAI Xu, HAN Chaoying, ZHU Hua   

  1. College of Chemistry, Sichuan University, Chengdu 610064, China
  • Received:2019-05-05 Revised:2019-07-23 Online:2019-08-10 Published:2019-07-12
  • Supported by:
    Supported by the National Natural Science Foundation of China(No.21373139) and the Sichuan Province Application Foundation, China(No.2018JY0712).

摘要: 采用[CCSD(T)]-F12方法和aug-cc-pVTZ基组,同时引入中心键函数(3s3p2d1f1g)构建了Kr-C2H2体系的高精度四维势能面.在构建势能面时考虑了分子间的振动方式及C2H2单体内的ν1对称伸缩和ν3反对称伸缩振动.将计算得到的四维势能面在Q1方向和Q3方向分别做积分得到C2H2单体分别处于振动基态和(ν1ν3)=(1,1)激发态的平均势能面.计算结果表明,这2个平均势能面均存在2个等价的T型全局极小值和2个等价线性极小值.全局极小值的几何构型位于R=0.41 nm,θ=65.6°/114.4°,势阱深度为151.88 cm-1.对径向部分采用离散变量表象法(DVR),角度部分采用有限基组表象法(FBR),并结合Lanczos循环算法计算了Kr-C2H2的振转能级和束缚态.计算结果表明,复合物在(ν1ν3)=(1,1)区域的带心位移为-1.48 cm-1,表现为红移,与实验值-1.38 cm-1很接近;计算得到的红外跃迁频率也与实验值相吻合,说明得到的从头算势能面具有高精度.

关键词: Kr-C2H2, 势能面, 振转光谱, 分子内振动激发

Abstract: A new four-dimensional(4D) potential energy surface(PES) for the Kr-C2H2 complex including the Q1 and Q3 normal modes for the ν1 symmetric stretching vibration and ν3 antisymmetric stretching vibration of C2H2 was studied. The PES was calculated at the coupled-cluster singles and doubles with noniterative inclusion of connected triples[CCSD(T)] -F12 level with augmented correlation-consistent polarized-valence quadruplet-zeta(aug-cc-pVTZ) basis set plus the midpoint bond function(3s3p2d1f1g). Two averaged vibrational potential energy surfaces of C2H2 at both the vibrational ground and (ν1,ν3)=(1,1) excited states were generated from the integration of the four-dimensional potential over the Q1 and Q3 coordinates. The averaged potential energy surfaces have two equivalent T-shaped global minima, two equivalent local linear minima as well as three saddle points between the minima. The global minima are located at R=0.41 nm and θ=65.6°/114.4° with a well depth of 151.88 cm-1. The radial discrete variable representation(DVR)/angular finite basis representation(FBR) method and Lanczos algorithm were employed to calculate the rovibrational energy levels and bound states. The calculated vibrational band origin for the Kr-C2H2 complex is red shifted by -1.48 cm-1, which is closed to the observed value of -1.38 cm-1. The infrared spectra agree well with the experiment data. The good agreement with the experiment values verifies the high quality of ab initio PESs.

Key words: Kr-C2H2, Potential energy surface, Rovibrational spectra, Intramolecular vibrational excitation

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