H$)$ Two argon atoms form the molecule $A{r}_2$ as a result of the van der Waals interaction with $U_{-}0=1\mathrm{.}68e-21J$ and $r_{-}0=3\mathrm{.}82e-10.$ Find the frequency of oscillation of one of the Ar atoms about equilibrium.

$U(r)=U_0(\frac{r_0}{r}{)}^{12}-2(\frac{r_0}{r}{)}^6$