  The QCD inspired potential model persued by us earlier has been recently
modified to incorporate an additional factor 'c' in the linear cum Coulomb
potential. While it felicitates the inclusion of standard confinement parameter
b = 0.183GeV 2, unlike in previous work, it still falls short of explaining the
Isgur-Wise function for the B mesons without adhoc adjustment of the strong
coupling constant. In this work, we determine the factor 'c' from the
experimental values of decay constants and masses and show that the reality
constraint on 'c' yeilds bounds on the strong coupling constant as well on
slope and curvature of Isgur-Wise function allowing more flexibility to the
model.
