content_image/348615.jpg content_image/348613.jpg content_image/348614.jpg content_image/348612.jpg
<img src='content_image/348615.jpg'>

<img src='content_image/348613.jpg'>

<img src='content_image/348614.jpg'>

<img src='content_image/348612.jpg'>

of a thermodynamic system with respect to small variations of the thermodynamic coordi- nates is usually performed by analyzing the behavior of the entropy S ( M, Q ) around the equilibrium. The local stability in any ensemble requires that S ( M, Q ) be a convex function of the extensive variables or its Legendre transformation must be a concave function of the intensive variables. The stability can also be studied by the behavior of the energy M ( S, Q ) which should be a convex function of its extensive variable. Thus, the local stability can in principle be carried out by finding the determinant of the Hessian matrix of M ( S, Q ) with respect to its extensive variables X$_{i}$ , H M X$_{i}$X$_{j}$ = [ ∂ $^{2}$M/∂X$_{i}$ ∂X$_{j}$ ] [33, 37]. In our case the mass M is a function of entropy and charge. The number of thermodynamic variables depends 

