  Large-scale relativistic configuration-interaction calculation of energy
levels of core-excited states of lithium-like ions is presented. Quantum
electrodynamic, nuclear recoil, and frequency-dependent Breit corrections are
included in the calculation. The approach is consistently applied for
calculating all $n=2$ core-excited states for all lithium-like ions starting
from argon ($Z = 18$) and ending with krypton ($Z = 36$). The results obtained
are supplemented with systematical estimations of calculation errors and
omitted effects.
