Browsing by Author "Jellinek, Julius"

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Citation Count: Avcı, H...et al. "Collisionless fragmentation of non-rotating Ni-n (n=4-14) clusters: a molecular dynamics study" Journal Of Physics B-Atomic Molecular And Optical Physics, Vol.36, No.16, pp.3487-3507
Collisionless fragmentation of non-rotating Ni-n (n=4-14) clusters: a molecular dynamics study
(IOP Publishing LTD, 2003) Avcı, H.; Çivi, M.; Güvenç, Ziya B.; Jellinek, Julius
Collisionless fragmentation of non-rotating Ni-n (n = 4-14) clusters is studied using micro-canonical molecular dynamics (MD) computer simulations. The clusters are modelled by an embedded-atom potential energy surface. The distributions of the channel-specific fragmentation probabilities, and the global and channel-specific fragmentation rate constants are computed and analysed as functions of the internal energy and size of the clusters. The trends derived from the dynamical calculations are compared to the fragmentation energy patterns, those of the Rice-Ramsperger-Kassel (RRK) and statistical approaches. The rate constants are an order of magnitude smaller for the RRK model than with both the MD and transition-state theory approaches. The results are also compared with the other multi-channel fragmentation works.
Citation Count: Böyükata, Mustafa...at all (1999). "D2 +Nin(T), n=7 and 9, Collision System", Mathematical and Computational Applications, Vol. 4, No. 1, pp. 61-67.
D2 +Nin(T), n=7 and 9, Collision System
(1999) Böyükata, Mustafa; Durmuş, Perihan; Özçelik, Süleyman; Güvenç, Ziya Burhanettin; Jellinek, Julius
In this study the kinetics of reactions of Nin n=7 and 9, clusters with a deuterium D2 molecule are studied via quasiclassical molecular dynamics. Dissociative chemisorption probabilities as functions of impact parameters, collision energies, and a rovibrational state of a molecule are calculated. And the corresponding reactive cross sections are evaluated. Resonance formation in the low collision energy region is discussed.
Citation Count: Avcı, Halil...et al (1999). "Fragmentation of a Non-Rotating Ni19 Cluster: A Molecular Dynamics Study", Mathematical and Computational Applications, Vol. 4, No. 2, pp. 99-106.
Fragmentation of a Non-Rotating Ni19 Cluster: A Molecular Dynamics Study
(1999) Avcı, Halil; Çivi, Mehmet; Güvenç, Ziya Burhanettin; Jellinek, Julius
Collisionless fragmentation of a non-rotating Ni19 cluster is studied using constant-energy molecular dynamics computer simulations. The cluster is modelled by an embedded atom model (EAM) energy surface. Distribution of the channel-specific fragmentation probabilities, and global rate constants are computed and analyzed as functions of the internal energy of the cluster. The results are compared with those obtained using the RRK statistical approach, and also compared with the other multi-channel fragmentation work.
Citation Count: Boyukata, M...et.al., "Reaction dynamics of Ni(n) (n=19 and 20) with D(2): Dependence on cluster size, temperature and initial rovibrational states of the molecule", International Journal Of Modern Physics C, Vol.16, No.2, pp.295-308, (2005).
Reaction dynamics of Ni(n) (n=19 and 20) with D(2): Dependence on cluster size, temperature and initial rovibrational states of the molecule
(World Scientific Publ CO PTE LTD, 2005) Böyükata, Mustafa; Güvenç, Büşra; Özçelik, Süleyman; Durmuş, Perihan; Jellinek, Julius
The Ni(n)(n = 19, 20) + D2(v, j) collision systems have been studied to investigate the dependence of cluster reactivity on the cluster temperature and the initial rovibrational states of the molecule using quasiclassical molecular dynamics simulations. The clusters are described by an embedded atom potential, whereas the interaction between the molecule and the cluster is modeled by a LEPS (London-Eyring-Polani-Sato) potential energy function. Reaction (dissociative adsorption) cross-sections are computed as functions of the collision energy for different initial rovibrational states of the molecule and for different temperatures of the clusters. Rovibrational, temperature and size-dependent rate constants are also presented, and the results are compared with earlier studies. Initial vibrational excitation of the molecule increases the reaction cross-section more efficiently than the initial rotational excitation. The reaction cross-sections strongly depend on the collision energies below 0.1 eV.
Citation Count: Durmus, P...et al., "Reactions of small Ni clusters with a diatomic molecule: MD simulation of D(2)+Ni(n) (n=7-10) systems", 18th European Conference on Surface Science (ECOSS 18), Vol. 454, pp. 310-315, (2000).
Reactions of small Ni clusters with a diatomic molecule: MD simulation of D(2)+Ni(n) (n=7-10) systems
(2000) Durmuş, Perihan; Böyükata, Mustafa; Özçelik, Süleyman; Güvenç, Ziya B.; Jellinek, Julius
The kinetics of the reactions of nickel clusters with a deuterium molecule are studied, Dissociative chemisorption probabilities of the D(2) molecule on the small Ni(n) (n=7-10) clusters are computed by a quasi-classical molecular dynamics computer simulation technique. Structures of the clusters are obtained by an embedded-atom potential, and the interaction between the D(2) and Ni(n) is modelled by an LEPS (London-Eyring-Polanyi-Sato) function (energy surface). This analysis includes the chemisorption probabilities as functions of the impact parameter and of the relative translational energy of the D(2). The corresponding reactive cross-sections for the ground state of the molecule are calculated as functions of the collision energy and the size of the cluster. The role of the size of the clusters is examined. An indirect mechanism to the reaction, which involves formation of molecular adsorption as precursors to dissociative adsorption in the low collision energy region (less than 0.1eV), is observed. Results are discussed by comparing with the other similar theoretical and experimental studies. (C) 2000 Elsevier Science B.V. All rights reserved.
Citation Count: Ozçelik, S...et al. "Reactivity of the Ni(n)(T) (n=54,55,56) clusters with D(2)(v,j) molecule: molecular dynamics simulations" Surface Science, Vol.566, pp.377-382, (2004).
Reactivity of the Ni(n)(T) (n=54,55,56) clusters with D(2)(v,j) molecule: molecular dynamics simulations
(Elsevier Science BV, 2004) Özçelik, Süleyman; Güvenç, Ziya B.; Durmuş, Perihan; Jellinek, Julius
The reactive channel of the D(2) (v, j) + Ni(n) (T) (n = 54, 55, 56) collision system is studied via quasiclassical molecular dynamics simulations. The cluster is described using an embedded-atom potential, and the interaction between the molecule and the cluster is modeled by a LEPS (London-Eyring-Polanyi-Sato) potential energy function. Dissociative chemisorption probabilities are computed as functions of the impact parameter and the collision energy, and are used to evaluate the reaction cross-sections. Effects of the initial rovibrational states of the molecule and the temperatures of the clusters on the reactive channel are analyzed. Reaction rate constants are also computed and compared with those measured experimentally.
Citation Count: Güvenç, Ziya B.; Güvenç, Dilek; Jellinek, Julius (1999). "Structural forms and energies of Nin, n = 12-14, clusters", Mathematical and Computational Applications, Vol. 4, No. 1, pp. 75-81.
Structural forms and energies of Nin, n = 12-14, clusters
(1999) Güvenç, Ziya B.; Güvenç, Dilek; Jellinek, Julius
Equilibrium structural forms of the Nin, n = 12-14, clusters, as defined by an embedded-atom potential, are obtained using molecular dynamics and thermal quenching simulations. The isomers (locally stable geometric forms) are distinguished from those stationary structures that correspond to saddle points of the potential energy surface. Isomer statistics are obtained using a large number of initial quenching configurations generated along high-energy trajectories (the energies are high enough to `melt' the clusters). Probabilities of sampling the basins of attraction of the different isomers are computed and the spectra of their energies are analyzed.
Citation Count: Güvenç, Ziya B...et al. "Structure and reactivity of Ni(n) (n=7-14, 19) clusters" International Journal Of Quantum Chemistry, Vol.84, No.2, pp.208-215, (2001).
Structure and reactivity of Ni(n) (n=7-14, 19) clusters
(Wiley-Blackwell, 2001) Böyükata, Mustafa; Güvenç, Ziya B.; Özçelik, Süleyman; Durmuş, Perihan; Jellinek, Julius
Results of a computer simulation study of Ni(n) (n = 7-14, 19) clusters, their structures, energetics, and reactivity with a D(2) molecule are presented. The clusters are described by an embedded atom potential, whereas the interaction between the molecule and the clusters is modeled by an LEPS (London-Eyring-Polanyi-Sato) potential energy function. The focus is on structures of the dusters and their reactive channels. The total numbers of stable isomers of the clusters are obtained by sampling their phase space, and the isomers' energy spectra are determined. On the reactive side, dissociative chemisorptions cross sections and decay-rate constants are calculated. (C) 2001 John Wiley & Sons, Inc.