INCOMMENSURABILITY OF HCP SOLID 4 He QUANTUM CRYSTAL

Chelimo, Khanna, Rapando, Kandie, Masinde, Bitok
2013 International Journal of Physics and Mathematical Sciences   unpublished
The thermodynamic properties of an incommensurate hcp solid 4 he quantum crystal are calculated. The ground state of a quantum crystal is assumed to be incommensurate with point defects; zero-point vacancies and interstitials. We show that vacancies contribution to the specific heat varies as t 3/2 .the vacancy contribution to the specific heat increases at larger temperatures due to thermal excitations. The correction to the specific heat due to both phonon dispersion and vacancies is reminiscent of what has been found experimentally.
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