  The aim of the present contribution is to provide a framework for analyzing
and visualizing the correlated many-electron dynamics of molecular systems,
where an explicitly time-dependent electronic wave packet is represented as a
linear combination of $N$-electron wave functions. The central quantity of
interest is the electronic flux density, which contains all information about
the transient electronic density, the associated phase, and their temporal
evolution. It is computed from the associated one-electron operator by reducing
the multi-determinantal, many-electron wave packet using the Slater-Condon
rules. Here, we introduce a general tool for post-processing multi-determinant
configuration-interaction wave functions obtained at various levels of theory.
It is tailored to extract directly the data from the output of standard quantum
chemistry packages using atom-centered Gaussian-type basis functions. The
procedure is implemented in the open-source Python program detCI@ORBKIT, which
shares and builds upon the modular design of our recently published
post-processing toolbox [J. Comput. Chem. 37 (2016) 1511]. The new procedure is
applied to ultrafast charge migration processes in different molecular systems,
demonstrating its broad applicability. Convergence of the $N$-electron dynamics
with respect to the electronic structure theory level and basis set size is
investigated. This provides an assessment of the robustness of qualitative and
quantitative statements that can be made concerning dynamical features observed
in charge migration simulations.
