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首页> 外文期刊>Chimia >Non-empirical Prediction of the Photophysical and Magnetic Properties of Systems with Open d- and f-Shells Based on Combined Ligand Field and Density Functional Theory (LFDFT)
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Non-empirical Prediction of the Photophysical and Magnetic Properties of Systems with Open d- and f-Shells Based on Combined Ligand Field and Density Functional Theory (LFDFT)

机译：基于配体场和密度泛函理论（LFDFT）的d壳和f壳开放系统的光物理和磁性能的非经验预测

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Despite the important growth of ab initio and computational techniques, ligand field theory in molecular science or crystal field theory in condensed matter offers the most intuitive way to calculate multiplet energy levels arising from systems with open shells d and/or f electrons. Over the past decade we have developed a ligand field treatment of inorganic molecular modelling taking advantage of the dominant localization of the frontier orbitals within the metal-sphere. This feature, which is observed in any inorganic coordination compound, especially if treated by Density Functional Theory calculation, allows the determination of the electronic structure and properties with a surprising good accuracy. In ligand field theory, the theoretical concepts consider only a single atom center; and treat its interaction with the chemical environment essentially as a perturbation. Therefore success in the simple ligand field theory is no longer questionable, while the more accurate molecular orbital theory does in general over-estimate the metal-ligand covalence, thus yields wave functions that are too delocalized. Although LF theory has always been popular as a semi-empirical method when dealing with molecules of high symmetry e.g. cubic symmetry where the number of parameters needed is reasonably small (3 or 5), this is no more the case for molecules without symmetry and involving both an open d- and f-shell (# parameters ～90). However, the combination of LF theory and Density Functional (DF) theory that we introduced twenty years ago can easily deal with complex molecules of any symmetry with two and more open shells. The accuracy of these predictions from 1st principles achieves quite a high accuracy (＜5%) in terms of states energies. Hence, this approach is well suited to predict the magnetic and photo-physical properties arbitrary molecules and materials prior to their synthesis, which is the ultimate goal of each computational chemist. We will illustrate the performance of LFDFT for the design of phosphors that produces light similar to our sun and predict the magnetic anisotrbpy energy of single ion magnets.
机译：尽管从头算和计算技术有了重要的发展，但是分子科学中的配体场论或凝聚态中的晶体场论提供了最直观的方法来计算由具有开壳d和/或f电子的系统产生的多重能级。在过去的十年中，我们利用金属球体内前沿轨道的优势定位，开发了一种无机分子模型的配体场处理方法。在任何无机配位化合物中都观察到的这一特征，特别是如果通过密度泛函理论计算得到的话，则可以以惊人的良好准确性确定电子结构和性能。在配体场论中，理论概念仅考虑单个原子中心；它只涉及一个原子中心。并将其与化学环境的相互作用本质上视为一种扰动。因此，简单配体场论的成功不再值得怀疑，而更精确的分子轨道理论通常确实高估了金属-配体的共价，因此产生的波函数过于局限。尽管在处理高对称性分子时，例如LF理论一直很流行作为半经验方法。立方对称，其中所需参数的数量相当少（3或5），对于没有对称性且涉及开敞的d壳和f壳的分子，则不再是这种情况（＃个参数〜90）。但是，我们二十年前引入的LF理论和密度泛函（DF）理论的结合可以轻松地处理具有两个或更多开放壳的任何对称复杂分子。根据第一原理，这些预测的精度在状态能量方面达到了很高的精度（＜5％）。因此，该方法非常适合在合成之前预测任意分子和材料的磁性和光物理性质，这是每个计算化学家的最终目标。我们将说明LFDFT在设计磷光体时的性能，该磷光体产生类似于太阳的光，并预测单个离子磁体的磁各向异性能。

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