The method of computation of the latent heat based on the energy distribution histogram is applied to the standard 3D Ashkin-Teller (AT) model. Similarly as in the original method for the q-state Potts model for strong first order phase transitions, the characteristic histogram with two peaks in the critical region have been observed. Positions of two minima of negative logarithm of internal energy probability for samples of finite size show good linear scalability to the thermodynamic limit. The applicability of this method has been confirmed by proving that the latent heat values are consistent with the ones obtained by us using the analysis of the behavior of the cumulants of the type of Challa and of Lee-Kosterlitz. The presented method is far more efficient than the one based on those cumulants. [2] in terms of two Ising models put on the same lattice with spins s i and σ i at each lattice site i. In consequence, only two-spin interactions of a constant magnitude J 2 between the nearest neighbors are considered. These Ising models are extended to the AT one by the four-spin interaction of a constant magnitude J 4 also only between couples of nearest-neighboring spins. Thus, the effective Hamiltonian H is of the formwhere K i ¡J i {k B T , with i 2 or 4, ri, js denotes summation over nearest-neighboring lattice sites, and T is the temperature of the system.We consider this standard AT model in 3D put on the cubic lattice. It should be called the standard one as there are many extensions of the AT model (see e.g. Its K 2 pK 4 q phase diagram high complexity is the consequence of the fact that three components of the order parameter can order independently: not only xsy and xσy, but also xsσy where x. . .y denotes the thermal average.The aim of our paper is to present the method of computation of latent heat based on the energy distribution histogram, originally proposed for the q-state Potts * corresponding author; e-mail: djeziorek@wp.pl model [11], applied by us to the 3D AT model. To confirm the applicability of this method, we compare results of our analysis with the ones obtained by us using the analysis of the behavior of the cumulants of the type of Challa V L [12] and Lee-Kosterlitz U L [11], modified by us [7,10]. The latter for the first time applied by us to the AT model what is explained in Section 2. Similarly as in the original method for the q-state Potts model [11] for strong first order phase transitions, in Section 3 we demonstrate the characteristic histogram with two peaks in the critical region also in the 3D AT model and we compute the latent heat on this basis.
The method of computationJust like in the q-state Potts model with q equivalent ordered states and one disordered, we observe characteristic histogram of two peaks in the critical area also in the 3D AT model. As shown on the right in Fig. 1 for spins s, maxima of these peaks appear at the energy value E ¡,L for the ordered state and at E ,L for the disordered one, and they are separated by a minimum of E m,L . In this paper we ...