  The value of adjustable parameter $C$ and the four-parameter potential $U(r)
= D_{e}\left [ \frac{1-{exp}[-b(r-r_{e})]}{1-C{exp} [-b(r-r_{e})]} \right
]^{2}$ has been expressed in terms of molecular parameters and its significance
has been brought out. The potential so constructed, with $C$ derived from the
molecular parameters, has been applied to ten electronic states in addition to
the states studied by Wei Hua. Average mean deviation has been found to be 3.47
as compared to 6.93, 6.95 and 9.72 obtained from Levine2, Varshni and Morse
potentials, respectively. Also Dunham's method has been used to express
rotation-vibration interaction constant $(\alpha_{e})$ and anharmonocity
constant $(\omega_{e}x_{e})$ in terms of $C$ and other molecular constants.
These relations have been employed to determine these quantities for 37
electronic states. For $\alpha_{e}$, the average mean deviation is 7.2%
compared to 19.7% for Lippincott's potential which is known to be the best to
predict the values. Average mean deviation for $(\omega_{e}x_{e})$ turns out to
be 17.4% which is almost the same as found from Lippincott's potential
function.
