| Autor: |
Vidal EJ; Instituto de Física, Universidade Federal de Alagoas, Maceió AL, Brazil., Lima RP, Lyra ML |
| Jazyk: |
angličtina |
| Zdroj: |
Physical review. E, Statistical, nonlinear, and soft matter physics [Phys Rev E Stat Nonlin Soft Matter Phys] 2011 Jun; Vol. 83 (6 Pt 1), pp. 061137. Date of Electronic Publication: 2011 Jun 23. |
| DOI: |
10.1103/PhysRevE.83.061137 |
| Abstrakt: |
In this work, we provide exact solutions for the ideal boson lattice gas on the infinitely ramified star and wheel graphs. Within a tight-binding description, we show that Bose-Einstein condensation (BEC) takes place at a finite temperature after a proper rescaling of the hoping integral ɛ connecting a central site to the peripheral ones. Analytical expressions for the transition temperature, the condensed gas fraction, and the specific heat are given for the star graph as a function of the density of particles n. In particular, the specific heat has a mean-field character, being null in the high-temperature noncondensed phase with a discontinuity at T(c). In the wheel graph, on which the peripheral sites form a closed chain with hopping integral t, BEC takes place only above a critical value of the ratio ɛ/t for which a gap ΔE appears between the ground state and a one-dimensional band. A detailed analysis of the BEC characteristics as a function of n and ΔE is provided. The specific heat in the high-temperature phase of the wheel graph remains finite due to correlations among the peripheral sites. |
| Databáze: |
MEDLINE |
| Externí odkaz: |
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