We present ab initio transition density cube (TDC) calculations of the coulombic couplings between chlorophyll and carotenoid pigments in the major light-harvesting complex of photosystem II (LHC II) based on the 2.72 angstrom structure [Liu et al., Nature 428(2004) 287-292]. A comparison with couplings calculated by the ideal dipole approximation (IDA) demonstrate that for inter-pigment distances of less than similar to 25 angstrom the IDA-values can deviate by up to one order of magnitude from the exact values calculated by the TDC-method. The largest deviations are observed for interactions involving Q(x) states because of a significant multipole character of the corresponding Q(x) transitions. (c) 2006 Elsevier B.V. All rights reserved.