Approaches for interpreting π electronic states and π electronic transitions

Abstract

AbstractsScope and limitations of different approaches which enable r electronic systems of topologically equivalent structures to be compared have been examined. Particular attention has been paid to analyses in terms of molecular subsystems.Les possibilites et les limites d'application des approches differents furent examinees, permettant de comparer des structures a-electroniques, qui sont topologiqument Cquivalentes. Une attention particuliere a etC donne aux analyses suivant les substructures molCculaires.Es werden die Anwendungsmoglichkeiten und Anwendungsgrenzen verschiedener Methoden untersucht, die erlauben, 7r-Electronensysteme topologisch-aquivalenter Strukturen zu vergleichen. Besondere Aufmerksamkeit wurde dabei Analysen nach molekularen Substrukturen gewidmet.

Electron invariants and excited state structural analysis for electronic transitions within CIS, RPA, and TDDFT models

“…But our diagram for S 1 says that the CT process N(CH 3 ) 2 →Phn is not negligible, so the first transition is rather reminiscent of that observed in dimethylaminobenzene or aniline. As for the latter, a clear evidence for the CT process NH 2 →Ph was long ago obtained within π‐theory 35, 38. We see that the same is true for the third and fourth transitions as well.…”

“…Thus, the excitation localization indices L A * and CT numbers l A → B provide a quantitative basis for interpreting electron transitions in the abovementioned terms of the locally excited configurations and the electron transfer configurations. These CT indices were extensively exploited in many spectroscopic studies, but mainly within the semiempirical framework 38(b), 39–41. Given the essentially more reliable TDDFT model, it makes sense to extent the same analysis to the TDDFT excited states.…”

“…Notice, the latter are not normalized in a natural way, and it would be worth extending the previous definition of CT numbers to RPA and the related TDDFT approach as well. Such an extension is motivated by the fact that the potential of the excited state structural analysis is not exhausted, as seen from recent papers 38–41.…”

Irreducible charge density matrices for analysis of many‐electron wave functions

“…A number of works are devoted to illustration and interpretation of molecular excited states, for instance 24, 96–101. Here, we discuss the utility of the bond index approach in describing the distribution of excitation over individual atoms in molecules.…”

“…The atomic excitation index gives an alternative account of localization of electronic excitation. It was originally introduced within our covariant approach 99, 100 and was often used in the past; see for instance 100, 102, 103. L can be expressed directly in terms of the orbital CT indices defined by Eq.…”