Using ab initio program MONSTERGAUSS and various basis sets, we calculated the potential curves between Li-Li and F-F atoms at wider nuclear distances. We also calculated the equilibrium nuclear distances of ground state molecules Li₂ (¹Σ_g⁺) and F₂(¹Σ_g⁺) and election corselation erergy with configuration interaction method(CI). The calculated results were discussed and compared with other's calculated and experimental results.