Thermodynamic properties of neutral Dirac particles in the presence of an electromagnetic field

In this paper, we investigate the thermodynamic properties of a set of neutral Dirac particles in the presence of an electromagnetic field in contact with a heat bath for the relativistic and nonrelativistic cases. In order to perform the calculations, the high temperatures regime is considered and the Euler–MacLaurin formula is taking into account. Next, we explicitly determine the behavior of the main thermodynamic functions of the canonical ensemble: the Helmholtz free energy, the mean energy, the entropy, and the heat capacity. As a result, we verify that the mean energy and the heat capacity for the relativistic case are twice the values of the nonrelativistic case, thus, satisfying the so-called Dulong–Petit law. In addition, we also verify that the Helmholtz free energy increases and the entropy decreases as functions of the electric field. Finally, we note that there exists no influence on the thermodynamic functions due to the magnetic field.