  Accurate atomic data are essential for opacity calculations and for abundance
analyses of the Sun and other stars. The aim of this work is to provide
accurate and extensive results of energy levels and transition data for C I -
IV. The Multiconfiguration Dirac-Hartree-Fock and relativistic configuration
interaction methods were used in the present work. To improve the quality of
the wave functions and reduce the relative differences between length and
velocity forms for transition data involving high Rydberg states, alternative
computational strategies were employed by imposing restrictions on the electron
substitutions when constructing the orbital basis for each atom and ion.
Transition data, e.g., weighted oscillator strengths and transition
probabilities, are given for radiative electric dipole (E1) transitions
involving levels up to 1s$^2$2s$^2$2p6s for C I, up to 1s$^2$2s$^2$7f for C II,
up to 1s$^2$2s7f for C III, and up to 1s$^2$8g for CIV. Using the difference
between the transition rates in length and velocity gauges as an internal
validation, the average uncertainties of all presented E1 transitions are
estimated to be 8.05%, 7.20%, 1.77%, and 0.28%, respectively, for C I - IV.
Extensive comparisons with available experimental and theoretical results are
performed and good agreement is observed for most of the transitions. In
addition, the C I data were employed in a reanalysis of the solar carbon
abundance. The new transition data give a line-by-line dispersion similar to
the one obtained when using transition data that are typically used in stellar
spectroscopic applications today.
