Recently, the method of fragment molecular orbital-based molecular dynamics (FMO-MD) was enhanced by including the three-body corrections (FMO3) [Y. Komeiji, Y. Mochizuki, T. Nakano, Chem. Phys. Lett. 484 (2010) 380]. This simulation protocol was applied to a droplet model consisting of a divalent zinc ion and 64 water molecules, in order to investigate the hydration structure in ab initio fashion. The first peak position of the Zn-O radial distribution function (RDF) was evaluated to be 2.05 angstrom at the FMO3-HF/6-31G level of theory, which was in agreement with an X-ray value of 2.06 +/- 0.02 angstrom. The coordination number was evaluated to be 6, corresponding to an octahedral coordination. (C) 2010 Elsevier B.V. All rights reserved.