The 4f energy levels and crystal-field parameters for several clusters representing the local coordination surroundings of Eu3+ in the bulk and nanocrystalline cubic Y2O3: Eu3+ crystals are obtained by using a method based on the combination of the DV-X-alpha calculation and the effective Hamiltonian method initialized by M. F. Reid et al. (J. Phys.: Condens. Matter, 2011, 23: 045501). The results are in reasonable agreement with the measured energy levels and the crystal-field parameters obtained from the least-square fitting. The charge transfer energies are also obtained for all the clusters from the DV-X-alpha calculation. The results indicate that, compared with the bulk Y2O3: Eu3+ crystal, the charge transfer band in the excitation spectra is red-shifted in the nanocrystal. (C) 2011 Elsevier B. V. All rights reserved.