Structural stability and energetics of zirconium microclusters Zr, (n = 3-13) have been investigated by molecular-dynamics simulations and density functional calculations. A semi-empirical modelpotential energy function has been parametrized for the zirconium element by using the dimer interaction potential energy profile of Zr-2, which is calculated by the relativistic density functional method. Stable structures of the microclusters for n = 3-13 have been determined by a molecular-dynamics simulation. Relativistic density functional calculations have been performed for n = 3-7. It has been found that zirconium microclusters prefer to form three-dimensional compact structures. (C) 2000 Elsevier Science B.V. All rights reserved.