The Energy $E$ Holding Together the Two Helium Atoms of An $\mathrm{He}_{2}$

Short Answer

The energy $E$ holding together the two helium atoms of an $\mathrm{He}_{2}$ molecule is given by $E=\frac{284}{r^{6}}-\frac{10.5}{e^{2.1 r}}$ nanoJoules where $r$ is the distance between the atoms in atomic units. The atoms of one helium atom are moving apart at 1.3 atomic units per second. How fast is the energy that holds the atoms together changing when $r=4.1$ atomic units?