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.

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

References provided by Crossref.org

Natural and magnetic circular dichroism spectra of nucleosides: effect of the dynamics and environment

Origins of Optical Activity in an Oxo-Helicene: Experimental and Computational Studies