Constrains on treating linear part as perturbation in a QCD Potential Model

We make a review of the different works of Quark Model which are based on Perturbation theory. We make a critical analysis of taking linear part of the Potential as perturbation with Coulombic part as parent and its reverse case. We find in the analysis that the linear part can be treated as perturbation for a set of larger values of $\alpha_{s}$ in the range $0.37 \leq \alpha_{s}\leq 0.75$ with a constant shift in the Cornell potential within range of $-0.4 GeV \leq c \leq -1 GeV$. Moreover with the same range of constant shift in the Potential, we expect better results with coulombic part as perturbation for $\alpha_{s}\leq 0.37$.