We modify the mesonic wave function by using a short distance scale $r_{0}$ in analogy with hydrogen atom and estimate the values of masses and decay constants of the open flavour charm mesons 𝐷, $D_{s}$ and $B_{c}$ within the framework of a QCD potential model. We also calculate leptonic decay widths of these mesons to study branching ratios and lifetime. The results are in good agreement with experimental and other theoretical values.
