  This contribution reports the study of a set of molecular
electronic-structure reorganization representations related to light-induced
electronic transitions, modeled in the framework of time-dependent
density-functional response theory. More precisely, the work related in this
paper deals with the consequences, for the electronic transitions
natural-orbital characterization, that are inherent to the use of auxiliary
many-body wavefunctions constructed a posteriori and assigned to excited states
- since time-dependent density-functional response theory does not provide
excited state ans\"atze in its native formulation. Three types of such
auxiliary many-body wavefunctions are studied, and the structure and spectral
properties of the relevant matrices (the one-electron reduced difference and
transition density matrices) is discussed and compared with the native
equation-of-motion time-dependent density functional response theory picture of
an electronic transition - we see for instance that within this framework the
detachment and attachment density matrices can be derived without diagonalizing
the one-body reduced difference density matrix. The common departure/arrival
wavefunction-based representation of the electronic transitions computed with
this method is discussed, and two such common departure/arrival density-based
pictures are also compared.
