The Landau-de Gennes model of the nematic-isotropic phase transition with the inclusion of the density change and a higher order term (sixth-order term) in a simple way is examined. The temperature difference TNI - T* obtained is in good agreement with the experimental one. We also obtained the value of the ratio (Q* - QNI)/QNI. The value of (Q* - QNI)/QNI is not improved over the earlier attempt, but there is a definite improvement in the value of TNI - T* which is obtained as 1.045 K. © World Scientific Publishing Company.