Using Molecular Dynamics and thermal quenching simulations the stable geometrical structures and energies of Cun (n=21-71) clusters are identified. The interaction between the cluster atoms is modeled by an Embedded-Atom Potential Surface, Voter and Chen's version. The stable geometrical structures and energies are obtained from 500 phase space coordinates generated along high-energy trajectories. The internal energy (about T=2500 K) is above the melting temperature of the Cun clusters. The thermal quenching technique is employed to remove slowly the internal kinetic energy of the clusters. Because of this slow minimization process the locally stable isomers are separated from those meta-stable ones.