DEVELOPMENT OF MOLECULAR THEORY FOR THE CALCULATION OF POTENTIAL ENEGY SURFACES

计算势能面的分子理论的发展

基本信息

批准号：
05453019
负责人：
HIRAO Kimihiko
金额：
$ 4.35万
依托单位：
THE UNIVERSITY OF TOKYO
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1993
资助国家：
日本
起止时间：
1993 至 1994
项目状态：
已结题

项目摘要

Single reference perturbation theory and cluster expansion theory such as symmetry adapted cluster and coupled cluster theories are very effective in describing dynamical correlation but fail badly in dealing with nondynamical correlation. CI is easily applied in multireference form and can handle nondynamical correlation but the CI expansion becomes less compact and less efficient as the number of electrons in the system grows. Therefore we have developed multireference based Rayleigh-Schrodinger perturbation theory. The MRMP is reliable and retains the attractive features of the single reference MP method. The theory has conceptual simplicity due to the independent electron pair model. It is almost size consistent. It is very efficient and cost effective. Multireference technique can dissociate a molecule correctly into its fragments. It is applicable to open shells and excited states.The state-specific MRMP has been sucessfully applied to the calculations of the potential energy surfaces of chemical reactions. Also the theory was applied to the study of valence and Rydberg excitation energies of benzene. The results compare well with the experiment. The calculated valence pi-pi^* excitation energies (experimental values in parentheses) are ^1B_<2u>,4.77 (4.90), ^1B_<1u>,6.28 (6.20), ^1E_<1u>,6.98 (6.94) and ^1E_<2g>,7.88 (7.80) eV,respectively. The Rydberg excitation energies are also predicted with an accuracy of 0.18 eV or better. Results of similar accuracy are obtained for the valence and Rydberg excitation energies for cyclopentadiene, furan, pyrrole, naphthalene and ozone.

单个参考扰动理论和群集扩展理论，例如对称的群集和耦合群集理论在描述动态相关性方面非常有效，但在处理非动力学相关性方面非常不良失败。 CI很容易以多种形式应用，并且可以处理非动力的相关性，但是随着系统中的电子数量的增长，CI膨胀变得不那么紧凑，效率较低。因此，我们已经开发了基于多方面的瑞利 - 雪橇扰动理论。 MRMP是可靠的，并保留了单个参考MP方法的吸引人特征。该理论由于独立的电子对模型而具有概念上的简单性。它几乎是一致的。这是非常有效且具有成本效益的。多偏射技术可以将一个分子正确分离到其片段中。它适用于开放壳和激发状态。特异性MRMP已成功地应用于化学反应的势能表面的计算。该理论也应用于苯的价和Rydberg激发能的研究。结果与实验良好。计算的价PI-PI ^*激发能（括号中的实验值）为 ^1B_ <2U>，4.77（4.90）， ^1B_ <1u>，6.28（6.20）， ^1e_ <1u>，6.98（6.98（6.94）和6.98（6.94）和 ^1E___________ <2g>，7.88（7.88（7.88）（7.88（7.80）） Rydberg激发能的精度为0.18 eV或更高。对于环戊二烯，Furan，吡咯，萘和臭氧的价值和Rydberg激发能，获得了相似精度的结果。