Abstract
A simple semiclassical H\'enon-Heiles model is constructed based on Dirac's time-dependent variational principle. We obtain an effective semiclassical Hamiltonian using a Hatree-type two-body trial wavefunction in the Jackiw-Kerman form. Numerical results show that quantum effects can in fact induce chaos in the non-chaotic regions of the classical H\'enon-Heiles model.