We present the low-energy electronic structure originating from the S-8(7/2) ground multiplet of the Eu2+ ions derived from theoretical description of the temperature dependence of the specific heat at low temperatures, including the lambda-type peak at T-N, both at zero field and in external magnetic fields. The derived energy states are the physical reality-they can be probed by different techniques and on this basis results of different theoretical models can be compared. Our atomic-like approach consistently explains zero-temperature properties and thermodynamics. We separate the derived molecular field at T = 0 K of 2.73 T for contributions coming from antiferro- and ferromagnetic interactions and derived exchange constants J(1) = -16.6 mK (AF) and J(2) = +35.3 mK (F). (C) 2016 Elsevier B.V. All rights reserved.