  In this work, we investigate the spectroscopy and decay rates of charmonia
within the framework of non-relativistic Schr\"{o}dinger equation by employing
an approximate inter quark-antiquark potential. The spin hyperfine, spin-orbit
and tensor components of the one gluon exchange interaction are employed to
compute the spectroscopy of the excited S states and few low-lying P and D
waves. The resultant wave functions at zero inter quark separation as well as
some finite separation are employed to predict the di-gamma, di-leptonic and
di-gluon decay rates of charmonia states by using the conventional Van
Royen-Weisskopf formula. The di-gamma and di-leptonic decay widths are also
computed by incorporating the relativistic corrections of order $v^4$ within
the NRQCD formalism. We have observed that the NRQCD predictions with their
matrix elements computed at finite radial separation yielded results which are
found to be in better agreement with experimental value for both di-gamma and
di-leptonic decays. The same scenario is seen in the case when di-gamma and
di-leptonic decay widths are computed with Van Royen-Weisskopf formula. It is
also observed that the di-gluon decay width with the inclusion of binding
energy effects are in better agreement with the experimental data available for
1S-2S and 1P. The di-gluon decay width of 3S and 2P waves waves are also
predicted. Thus, the present study of decay rates clearly indicates the
importance of binding energy effects.
