Note
Morse potential
Manipulate[ Plot[ (1 - Exp[-a (r - R)])^2, {r, 0, 5}, PlotRange -> {-1, 2}] , {{a, 2}, 0, 10}, {{R, 2}, 0, 10}]
Reference
Wikipedia: Morse potential
Manipulate[ Plot[ (1 - Exp[-a (r - R)])^2, {r, 0, 5}, PlotRange -> {-1, 2}] , {{a, 2}, 0, 10}, {{R, 2}, 0, 10}]
Wikipedia: Morse potential