Structural stability and energetics of gold microclusters Aun (n=313,19-555) have been investigated by molecular-dynamics simulations. A model potential energy function has been parametrized for the gold element by using the dimer interaction potential energy profile of the Au2, which is calculated by relativistic density functional method. Stable structures of the microclusters for (n=3-13) have been determined by a molecular-dynamics simulation. It has been found that gold microclusters prefer to form three-dimensional compact structures. Molecular-dynamics simulations have also been performed for spherical gold clusters generated from fcc crystal structure with sizes (n=19-555 ).