Browsing by Author "Karabacak, M."

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Citation Count: Karabacak, M.; Özçelik,S.; Güvenç, Ziya B., "Dynamics of phase changes and melting of Pd-7 clusters" Acta Physica Slovaca, Vol.54, No.3, pp.233-243, (2004).
Dynamics of phase changes and melting of Pd-7 clusters
(Slovak Acad Sciences Inst Physics, 2004) Karabacak, M.; Özçelik, S.; Güvenç, Ziya B.
wWe have obtained the stable geometrical structures, energetics, melting behaviors and phase changes of Pd-7 clusters by using molecular dynamics and thermal quenching simulations. Cohesion of the clusters is modeled by an embedded-atom potential, which contains many-body atomic interactions. Isomers' energy-spectrum-width and their sampling probabilities are calculated. Melting phenomenon of a cluster is described in terms of relative root-mean-square bond-length fluctuations, and of behavior of the specific heats. The transition region from solid- to liquid-like phases is investigated, and the melting temperature of the cluster is estimated. Minimum energy pathways for the phase changes among the isomers of the Pd-7 are determined.
Citation Count: Karabacak, M.; Ozçelik, S.; Güvenç, Ziya B., "Structures and energetics of Pd-21-Pd-55 clusters" Surface Science, Vol.532, pp.306-311, (2003).
Structures and energetics of Pd-21-Pd-55 clusters
(Elsevier Science BV, 2003) Karabacak, M.; Özçelik, S.; Güvenç, Ziya B.
Using molecular dynamics and thermal quenching simulations the stable geometrical structures and energies of Pd-n (n = 21-55) clusters are identified. The interaction between the cluster atoms is modeled by an embedded-atom (EA) potential energy surface, Voter and Chen's version. The stable geometrical structures and their minimum energies are obtained from 500 phase space coordinates generated along high-energy trajectories. The internal energies (about T = 2500 K) are above the melting temperature of the Pd-n 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. Stability of the clusters is examined by the first and the second energy differences. The average bond lengths are obtained and analyzed as a function of the size of the clusters.