In this paper we continue the investigation of the lattice gas model. The main improvement is that we use two strengths for bonds: one between like particles and another between unlike particle to implement the isospin-dependence of nuclear force. The main effect is the elimination of unphysical clusters, like the dineutron or diproton. It is therefore a better description of nuclear system. Equation of state in mean field theory is obtained for nuclear matter as well as for N Z systems.

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... numerical and analytical calculation we show that the new model maintains all the important features of the older model. We study the effect of the Coulomb interaction on multifragmentation of a compound system of A=86, Z=40 and also for A=197, Z=79. For the first case the Coulomb interaction has small effect. For the latter case the effect is much more pronounced but typical signatures of the lattice gas model such as a minimum (maximum) in the value of τ (S_2) are still obtained but at a much lower temperature.