Peculiar features of heat capacity for Cu and Ni nanoclusters
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The heat capacity of copper and nickel clusters (from 2 to 6 nm in diameter) was investigated in the temperature range 200–800 K using molecular dynamics method and a modified tight-binding potential. The simulation results demonstrate a very good agreement with the available experimental data at T = 200 K and a fairy good agreement at higher temperatures. A number of regular trends are revealed in computer experiments which agree with the corresponding theoretical predictions. A conclusion is made that in the case of single free clusters the heat capacity may exceed the capacity of the corresponding bulk material. It is found that at 200 K, the copper nanocluster (D = 6 nm) heat capacity is higher by 10% and for nickel cluster by 13%. The difference diminishes with increasing the nanoparticles size proportionally to the relative number of surface atoms. A conclusion is made that very high values of the nanostructure heat capacity observed in laboratory experiments should not be attributed to free clusters, i.e., the effect in question is caused by other reasons.
KeywordsMolecular dynamics Heat capacity Copper and nickel clusters Modeling and simulation
This article was prepared under the financial support of Russian Foundation for Basic Research (grant No. 10-02-98-001-r_Siberia_a), grant of President of Russian Federation (No. MK-2207.2009.2) and in frames of the research program “Scientific and pedagogical stuffs of the innovation Russia 2009–2013”.
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