A theoretical investigation of the rare earth (RE³⁺) localized 4f energy spectrum at regular sites of RE Ba₂Cu₃O_6+x (x = 0, 1), and RE₂CuO₄ cuprates was performed. To predict the k=4 and 6 crystal field (CF) parameters B_kq, we employed the semiempirical superposition model (SM) used earlier for quantitative estimates of the CF interaction acting on 4f states in RE cuprates. The SM model does not apply for the k=2 CF parameters where the long range electrostatic contribution dominates. Therefore, to calculate the k=2 CF parameters, we used the parameter-free first-principles method based on the density functional theory.

PACS numbers: 74.72.Jt, 71.70.Ch, 71.70.Mb