Štěpánek Petr, Bouř Petr
Group of Molecular Spectroscopy, Institute of Organic Chemistry and Biochemistry, Academy of Sciences, Flemingovo nám. 2, 16610, Prague, Czech Republic; Institute of Physics, Faculty of Mathematics and Physics, Charles University, Ke Karlovu 5, 121 16, Prague, Czech Republic.
J Comput Chem. 2015 Apr 15;36(10):723-30. doi: 10.1002/jcc.23845. Epub 2015 Feb 7.
Although electronic and magnetic circular dichroism (ECD, MCD) spectra reveal valuable details about molecular geometry and electronic structure, quantum-chemical simulations significantly facilitate their interpretation. However, the simulated results may depend on the choice of coordinate origin. Previously (Štěpánek and Bouř, J. Comput. Chem. 2013, 34, 1531), the sum-over-states (SOS) methodology was found useful for efficient MCD computations. Approximate wave functions were "resolved" using time-dependent density functional theory, and the origin-dependence was avoided by placing the origin to the center of mass of the investigated molecule. In this study, a more elegant way is proposed, based on the localized orbital/local origin (LORG) formalism, and a similar approach is also applied to generate ECD intensities. The LORG-like approach yields fully origin-independent ECD and MCD spectra. The results thus indicate that the computationally relatively cheap SOS simulations open a new way of modeling molecular properties, including those involving the origin-dependent magnetic dipole moment operator.
尽管电子圆二色光谱（ECD）和磁圆二色光谱（MCD）能揭示有关分子几何结构和电子结构的重要细节，但量子化学模拟能极大地促进对这些光谱的解读。然而，模拟结果可能取决于坐标原点的选择。此前（Štěpánek和Bouř，《计算化学杂志》，2013年，34卷，1531页），态叠加（SOS）方法被发现对高效的MCD计算很有用。使用含时密度泛函理论对近似波函数进行“解析”，并通过将原点置于所研究分子的质心来避免原点依赖性。在本研究中，基于定域轨道/局域原点（LORG）形式主义提出了一种更简便的方法，并且也采用类似方法来生成ECD强度。类LORG方法能产生完全与原点无关的ECD和MCD光谱。因此结果表明，计算上相对便宜的SOS模拟为分子性质建模开辟了一条新途径，包括那些涉及依赖原点的磁偶极矩算符的性质。
