Thermosize effects in a q-deformed fermion gas model

We study the the high-temperature thermodynamic properties of the q-deformed fermion gas model by taking into account of the size effect of the gas particles. Starting from the logarithm of the grand partition function of the model, we calculate several thermodynamic functions of the model such as internal energy, entropy, and Helmholtz free energy by means of the deformation parameter q. Furthermore, the influences of the fermionic q-deformation on the thermosize effect in the confined deformed quantum gas systems such as the Seebeck-like and Peltier-like thermosize effects are discussed. Especially, we focus on the absorbed or released heat of the model in the Peltier-like thermosize effect. In the light of the results obtained in this work, we can conclude that the present q-deformed fermion model can be used to desing the new types of the micro-/nano-scaled quantum heat engines.

The occupancy of the threading dislocation lines within n-type gallium nitride: Recent progress

ABSTRACTWithin the framework of a grand partition function formalism, we examine the occupancy of the dangling bond dislocation defect sites and the VGa-ON dislocation defect sites within uncompensated n-type gallium nitride. The sensitivity of these results to variations in the unoccupied dislocation defect energy level is examined. We find that the VGa-ON dislocation defect sites’ greater capacity to store charge plays a large role in influencing the results, i.e., greater free electron and bulk donor concentrations are required in order to fully saturate the threading dislocation lines with charge.

SIMULTANEOUS ONSET OF CONDENSATION OF MOLECULES AND ATOMS IN AN ATTRACTIVE FERMI GAS OF ATOMS

The self-consistent equations for the order parameters of Bose–Einstein condensation (BEC) of molecules and Bardeen–Cooper–Schrieffer (BCS) condensation of atoms in a Fermi gas of atoms with an attractive two-body interaction between atoms have been derived within the Hartree–Fock–Bogoliubov approximation from the path integral representation of the grand partition function. We have found that the order parameters for BEC and BCS are proportional to each other, which implies that BEC and BCS onsets simultaneously. We have also found that the common critical temperature of BEC and BCS increases as the average number of molecules increases and that the atom-molecule coupling enhances the common critical temperature.

A FINITE-TEMPERATURE GENERALISATION OF THE COUPLED CLUSTER METHOD: A NON-PERTURBATIVE ACCESS TO GRAND PARTITION FUNCTIONS

We present here a succinct account of the finite-temperature generalisation of the coupled cluster (CC) method. It requires the concept of thermal normal ordered products whose Boltzmann trace is zero. The basic idea is to express the Boltzmann operator as a normal ordered exponential containing cluster operators and a number, and express the free energy as a logarithm of a suitable Boltzmann trace, where only the number part in the ordered exponential survives. The free energy is manifestly extensive. Free energies of Lipkin model and anharmonic oscillators obtained from the grand partition function are discussed as example applications.