Exploration of Excited Molecular States With Localized Orbital Locator Function

ABSTRACT

Localized orbital locator (LOL), which is a function derived from the kinetic energy density, is known to provide detailed features of the electronic structure of molecules in a way close to chemist's viewpoint, that is, by examining and quantifying interatomic connections. In this study we show that the extension of this function to electronic excited states gives an opportunity to explore modifications of the electronic structure caused by electronic excitations. In particular, changes of bond character, number and type of lone pairs, and emergence of long‐range features can be detected by the application of LOL to excited‐state and ground‐state densities. A good agreement between the conclusions from the LOL study and the hole‐particle natural transition orbitals (NTO) representation has been found, but the LOL description can be made quantitative and more detailed, if needed. Test calculations supporting these findings have been performed for selected small cases (ethene, tetrafluoroethene, and their dimer) and for the real‐life examples of benzaldehyde and 4‐pyridin‐1‐ium‐1‐ylphenolate.