A new approach for the development of diabatic potential energy surfaces: Hybrid block-diagonalization and diabatization by ansatz.
A new approach for the development of diabatic potential energy surfaces: Hybrid block-diagonalization and diabatization by ansatz.
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DOI：
10.1063/1.4967258
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发表时间：
2016-11
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通讯作者：
Nils Wittenbrink;Florian Venghaus;David M G Williams;W. Eisfeld
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作者：
Nils Wittenbrink;Florian Venghaus;David M G Williams;W. Eisfeld
提出了一种新的非绝热化方法，该方法适合于发展用于量子动力学研究的精确高维耦合势能面。该方法是基于同时使用绝热波函数和能量数据，分别，并结合块对角化和非绝热化的Anonymous方法。因此，它被称为混合糖尿病。合适的从头计算的绝热波函数投影到非绝热状态空间，得到的矢量是标准的块对角化一样，正交归一化。建立了一个参数化的非绝热模型哈密顿量，作为一个模型，它可以利用块对角化数据来寻找最优模型。最后，相对于从头算参考数据的参数进行优化，使得绝热能量和模型的本征值之间的偏差以及投影状态向量和模型的本征向量最小化。这种方法是特别有利的复杂的电子结构的问题，其中的非绝热状态空间必须具有更高的维度比计算的绝热状态的数量。这是处理入侵者状态问题的有效方法，入侵者状态在反应式系统中非常常见。波函数信息的使用还增加了每个数据点的信息内容，而没有额外的成本，这有利于处理高维系统的欠采样问题。新的方法和它的性能被证明通过应用到三个原型系统，臭氧（O3），碘甲烷（CH3I），和炔丙基（H2CCCH）。
A new diabatization method is presented, which is suitable for the development of accurate high-dimensional coupled potential energy surfaces for use in quantum dynamics studies. The method is based on the simultaneous use of adiabatic wave function and energy data, respectively, and combines block-diagonalization and diabatization by ansatz approaches. It thus is called hybrid diabatization. The adiabatic wave functions of suitable ab initio calculations are projected onto a diabatic state space and the resulting vectors are orthonormalized like in standard block-diagonalization. A parametrized diabatic model Hamiltonian is set up as an ansatz for which the block-diagonalization data can be utilized to find the optimal model. Finally, the parameters are optimized with respect to the ab initio reference data such that the deviations between adiabatic energies and eigenvalues of the model as well as projected state vectors and eigenvectors of the model are minimized. This approach is particularly advantageous for problems with a complicated electronic structure where the diabatic state space must be of higher dimension than the number of calculated adiabatic states. This is an efficient way to handle problems with intruder states, which are very common for reactive systems. The use of wave function information also increases the information content for each data point without additional cost, which is beneficial in handling the undersampling problem for high-dimensional systems. The new method and its performance are demonstrated by application to three prototypical systems, ozone (O3), methyl iodide (CH3I), and propargyl (H2CCCH).