Dynamics of atoms trapped in an optical dipole trap formed by a train of femtosecond laser pulses is studied in detail on example of Rb atoms. In computer simulation, it is proved that such a trap effectively confines the atoms at the pumping laser beam power in between 1 mW and 3 kW (pulse duration 100 fs). It is also shown that the resonant dipole-dipole interaction (RDDI) through which closely spaced in the micropotential wells atoms interact between each other becomes essential and can be significantly increased by shining the atoms with resonant probe laser beam. Varying both the parameters of the trap and intensity of the probe laser field, role of the RDDI in the atomic dynamics in the trap is clarified in detail.© (2010) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.