  A new Radiative Driven Implosion (RDI) model based on Smoothed Particle
Hydrodynamics (SPH) technique is developed and applied to investigate the
morphological evolutions of molecular clouds under the effect of ionising
radiation. This model self-consistently includes the self-gravity of the cloud
in the hydrodynamical evolution, the UV radiation component in the radiation
transfer equations, the relevant heating and cooling mechanisms in the energy
evolution and a comprehensive chemical network. The simulation results reveal
that under the effect of ionising radiation, a molecular cloud may evolve
through different evolutionary sequences. Dependent on its initial
gravitational state, the evolution of a molecular cloud does not necessarily
follow a complete morphological evolution sequence from type A to B to C, as
described by previous RDI models. When confronted with observations, the
simulation results provide satisfactory physical explanations for a series of
puzzles derived from Bright-Rimmed Clouds (BRCs) observations. The consistency
of the modelling results with observations shows that the self-gravity of a
molecular cloud should not be neglected in any investigation on the dynamical
evolution of molecular clouds when they are exposed to ionising radiation.
