Estimation of diffusion coefficient is of great importance in industrial processes. It finds its application in rating of existing units, designing of new equipment and units and also in research and development. The main proposition of this work is that introducing temperature dependent interaction parameters instead of the current practice of using temperature independent interaction parameters may lead to improvement in the prediction of self-diffusivity. Self-diffusivities of atomic argon were evaluated by means of the mean square displacement or the Einstein method using equilibrium molecular dynamics (MD) at a pressure of 13 bar and a temperature range from 90 K up to 135 K in the isobaric, isothermal NPT ensemble. The simulation was carried out using both temperature dependent and temperature independent interaction parameters. Temperature dependent interaction parameters simulations, in general, produce more accurate self-diffusivities than the values computed by temperature independent interaction parameters simulations. Comparing the two approaches, the relative percentage error is reduced by about 67% and the RMSD is reduced by about 64% by using the temperature dependent parameters approach, This is consistent with our previous work in the Gibbs ensemble for the generation of coexistence vapor-liquid equilibrium curves. Finite size effects were studied for systems of (500, 1000 and 2000) atoms, the results indicate slight improvement in the computed self-diffusivities, however the improvement is marginal when compared to the computational time which was doubled as the number of atoms doubled. The effect of time step size was also investigated on time step sizes of (2, 4, 6 and 8) fs; results indicate that time step size of 2 fs was sufficient to produce more accurate self-diffusion coefficient values. The effect of pressure was studied at pressures of 58.6 bar, 104.04 bar and 136.8 bar, the results shows that up to a pressure of 58.6 bar the proposed approach gives better estimation for the self-diffusivity of argon. For a pressure range between 58.6 bar and 104.4 there is no significant difference between both methods, while for a pressure greater than that the common approach of using temperature independent interaction parameters gives more accurate values than the proposed approche.