  We present a theoretical framework to describe state-resolved ionization
dynamics of neon atoms driven by ultraintense x-ray free-electron-laser pulses.
In general, x-ray multiphoton ionization dynamics of atoms have been described
by time-dependent populations of the electronic configurations visited during
the ionization dynamics, neglecting individual state-to-state transition rates
and energies. Combining a state-resolved electronic-structure calculation,
based on first-order many-body perturbation theory, with a Monte Carlo
rate-equation method, enables us to study state-resolved dynamics based on
time-dependent state populations. Our results demonstrate that
configuration-based and state-resolved calculations provide similar
charge-state distributions, but the differences are visible when resonant
excitations are involved, which are also reflected in calculated
time-integrated electron and photon spectra. In addition, time-resolved spectra
of ions, electrons, and photons are analyzed for different pulse durations to
explore how frustrated absorption manifests itself during the ionization
dynamics of neon atoms.
