  We use molecular dynamics simulations to investigate dynamic heterogeneities
and the potential energy landscape of the Gaussian core model (GCM). Despite
the nearly Gaussian statistics of particles' displacements, the GCM exhibits
giant dynamic heterogeneities close to the dynamic transition temperature. The
divergence of the four-point susceptibility is quantitatively well described by
the inhomogeneous version of the Mode-Coupling theory. Furthermore, the
potential energy landscape of the GCM is characterized by a geometric
transition and large energy barriers, as expected from the lack of activated,
hopping dynamics. These observations demonstrate that all major features of
mean-field dynamic criticality can be observed in a physically sound,
three-dimensional model.
