The calculation of physics parameters of semiconductor compounds is of great interest in order to evaluate their potential use in a wide class of optoelectronics devices. Different methods have been developed for these calculations, based on the Hartree-Fock Hamiltonian and on the Density Functional ones. Here, a theoretical study by using Crystal 06 software and ab initio Density Functional Theory and Hartree-Focks method with different basis functions was carried out in order to calculate the lattice energy and the energy gap of the MnGa$_2$Se$_4$ magnetic semiconductor compound. It is shown that it is possible to calculate physics parameters of MnGa$_2$Se$_4$ with the mentioned software but due to the multiple values reported in literature for the same parameter, it is not possible to determinate which of the bases used is more effective.