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© Centre for Modeling & Simulation, Savitribai Phule Pune University
| Title | First-Principles Investigation of Finite-Temperature Behavior in Small Sodium Clusters |
| Author/s |
Mal-Soon Lee
Department of Physics, Savitribai Phule Pune University, Pune 411 007 India S. Chacko, D. G. Kanhere Centre for Modeling and Simulation, Savitribai Phule Pune University, Pune 411 007 India |
| Abstract | A systematic and detailed investigation of the finite-temperature behavior of small sodium clusters, Nan, in the size range of n=8–50 are carried out. The simulations are performed using density-functional molecular dynamics with ultrasoft pseudopotentials. A number of thermodynamic indicators such as specific heat, caloric curve, root-mean-square bond-length fluctuation, deviation energy, etc., are calculated for each of the clusters. Size dependence of these indicators reveals several interesting features. The smallest clusters with n=8 and 10 do not show any signature of melting transition. With the increase in size, broad peak in the specific heat is developed, which alternately for larger clusters evolves into a sharper one, indicating a solidlike to liquidlike transition. The melting temperatures show an irregular pattern similar to the experimentally observed one for larger clusters [Schmidt et al., Nature (London) 393, 238 (1998)]. The present calculations also reveal a remarkable size-sensitive effect in the size range of n=40–55. While Na40 and Na55 show well-developed peaks in the specific-heat curve, Na50 cluster exhibits a rather broad peak, indicating a poorly defined melting transition. Such a feature has been experimentally observed for gallium and aluminum clusters [Breaux et al., J. Am. Chem. Soc. 126, 8628 (2004); Breaux et al., Phys. Rev. Lett. 94, 173401 (2005)]. |
| Keywords | |
| Download | [134K pdf] |
| Citing This Document | Mal-Soon Lee, S. Chacko, and D. G. Kanhere , First-Principles Investigation of Finite-Temperature Behavior in Small Sodium Clusters . Technical Report CMS-TR-20050829 of the Centre for Modeling and Simulation, Savitribai Phule Pune University, Pune 411007, India (2005); available at http://cms.unipune.ac.in/reports/. |
| Notes, Published Reference, Etc. | Published as Journal of Chemical Physics 123, 164310 (2005) |
| Contact | kanhere AT unipune.ac.in |
| Supplementary Material |