Electronic excitation energies of molecules in solution within continuum solvation models: Investigating the discrepancy between state-specific and linear-response methods
Electronic excitation energies of molecules in solution within continuum solvation models: Investigating the discrepancy between state-specific and linear-response methods
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DOI：
10.1063/1.2039077
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发表时间：
2005-10-01
影响因子：
4.4
通讯作者：
Tomasi, J
中科院分区：
文献类型：
--
作者：
Corni, S;Cammi, R;Tomasi, J
在最近的一篇文章[R。Cammi，S.科尼，B。Mennucci，and J. Tomasi，J.Chem.Phys.122，104513（2005）]，我们证明了在溶剂化的量子力学连续模型的框架中计算溶质激发能的两种不同方式--状态特异性（SS）和线性响应（LR）方法给出了不同的激发能表达式。特别地，它们在与溶剂的电子响应相关的术语上不同。在目前的工作中，我们进一步研究了这种差异，通过比较SS和LR的激发能表达式与通过一个简单的模型获得的溶质-溶剂系统，绕过连续溶剂化模型的基本假设之一，即，使用单一的Hartree产品的溶质和溶剂波函数来描述总的溶质-溶剂波函数。特别地，我们认为总溶质-溶剂波函数是两个溶质态和两个溶剂电子态的四个乘积的线性组合。为了最大限度地提高与量子力学连续模型的可比性，所得到的激发能的表达式是重铸的溶剂和溶剂化分子的量适当的响应函数。所提出的表达式与LR和SS的比较启发了这些方法所包含或忽略的术语的物理意义，并表明SS与四能级模型的结果一致，而LR包含了一个在以前的治疗中被归类为色散的术语，并忽略了另一个与静电有关的术语。最后讨论了LR缺陷的可能来源。(c)2005年美国物理学会。
In a recent article [R. Cammi, S. Corni, B. Mennucci, and J. Tomasi, J. Chem. Phys. 122, 104513 (2005)], we demonstrated that the state-specific (SS) and the linear-response (LR) approaches, two different ways to calculate solute excitation energies in the framework of quantum-mechanical continuum models of solvation, give different excitation energy expressions. In particular, they differ in the terms related to the electronic response of the solvent. In the present work, we further investigate this difference by comparing the excitation energy expressions of SS and LR with those obtained through a simple model for solute-solvent systems that bypasses one of the basic assumptions of continuum solvation models, i.e., the use of a single Hartree product of a solute and a solvent wave function to describe the total solute-solvent wave function. In particular, we consider the total solute-solvent wave function as a linear combination of the four products of two solute states and two solvent electronic states. To maximize the comparability with quantum-mechanical continuum model the resulting excitation energy expression is recast in terms of response functions of the solvent and quantities proper for the solvated molecule. The comparison of the presented expressions with the LR and SS ones enlightens the physical meaning of the terms included or neglected by these approaches and shows that SS agrees with the results of the four-level model, while LR includes a term classified as dispersion in previous treatments and neglects another related to electrostatic. A discussion on the possible origin of the LR flaw is finally given. (c) 2005 American Institute of Physics.