Department of Physics

Structural stability and energetics of nickel clusters, NiN (N =3-459), have been investigated by molecular-dynamics simulations. A size-dependent empirical model potential energy function has been used in the simulations. Stable structures of the microclusters with sizes N = 3-55 and clusters generated from fcc crystal structure with sizes N = 79-459 have been determined by molecular-dynamics simulations. It has been found that the five-fold symmetry appears on the surface of the spherical clusters. The average coordination number shows a size-dependent characteristic, on the other hand the average nearest-neighbor distance does not show a size-dependence.

Demartin, 1991). The rms, deviations of fitted atoms for these planes are 0.025 and 0.057 ,~, the maximum deviations from these planes are 0.04 (3),4, for C6 and 0.164 (3)A for C1A. The two five-membered rings adopt envelope conformations with C15 and C15A at the flaps. ...

Melting and fragmentation behaviors of Ni 429 cluster have been studied with molecular-dynamics simulations using a size-dependent empirical model potential energy function. To monitor thermal behaviors of the cluster, we calculated some physical quantities such as average potential energy per atom, specific heat, radial atomic distribution, bond length distribution, average interatomic distance, nearest neighbor distance and average coordination number as a function of temperature. The roles of the surface and core atoms in the melting and fragmentation process of the cluster are also investigated by considering the surface and the bulk coordination numbers of the cluster.

This study was carried out to identify the misconceptions about heat and temperature. For this purpose, a conceptual test on heat and temperature was developed. This test was given to 1017 high school and university students. All the students were taught heat and temperature subjects. As a result of the analysis of the collected data, some misconceptions shared by students about heat and temperature have been determined.