Spin coupling and magnetic field effects on the finite-size free energy and its non-extensivity for 1-D Ising model with nearest and next-nearest neighbor interactions in nanosystem |
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Authors: | Farid Taherkhani Hadi Abroshan Alessandro Fortunelli |
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Affiliation: | 1. Department of Chemistry , Razi University , Kermanshah , Iran;2. CNR-IPCF, Istituto per i Processi Chimico-Fisici del CNR , Pisa , Italy f.taherkhani@razi.ac.ir;4. Department of Chemistry , Carnegie Mellon University , Pittsburgh , PA , USA;5. CNR-IPCF, Istituto per i Processi Chimico-Fisici del CNR , Pisa , Italy |
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Abstract: | The effects of second-neighbor spin coupling interactions and a magnetic field are investigated on the free energies of a finite-size 1-D Ising model. For both ferromagnetic of nearest neighbor (NN) and next-nearest neighbor (NNN) spin coupling interactions, the finite-size free energy first increases and then approaches a constant value for any size of the spin chain. In contrast, when NNN and NN spin coupling interactions are antiferromagnetic and ferromagnetic, respectively, the finite-size free energy gradually decreases by increasing the competition factor and eventually vanishes for large values of it. When a magnetic field is applied, the finite-size free energy decreases with respect to the case of zero magnetic fields for both ferromagnetic and antiferromagnetic spin coupling interactions. Deviation of free energy per size for finite-size systems relative to the infinite system increases when the spin coupling interactions as well as the f parameter (the ratio of the magnetic field to NN spin coupling interaction) increase. |
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Keywords: | Ising model spin coupling interaction magnetic field finite-size free energy nanosystem |
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