A previously developed method of coupled coherent states (CCS) is applied to the simulation of intramolecular vibrational energy redistribution in the CHD3 molecule. All nine modes are taken into account within a fully quantum approach. Emphasis is placed on convergence with respect to the number of coherent states in relation to the desired propagation time, which was taken to be sufficient to resolve Fermi resonance splitting of similar to100 cm(-1) at an excitation energy of similar to16 000 cm(-1). Fermi-resonance beatings of energy between C-H stretch and two C-H bends as well as slow energy flow to the rest of the molecule are reproduced. Due to the use of Monte Carlo grids the CCS technique scales extremely well with the number of modes and allows fully quantum molecular dynamics simulations of polyatomic systems. (C) 2003 American Institute of Physics.