On the sampling of microcanonical distribution for rotating triatomic molecules Original Research Article

For a rotating harmonic molecule, we suggest a successive sampling method from a microcanonical ensemble which allows one to specify the energies of any number of normal modes, and the energies of active and adiabatic rotations. The method is checked by comparing the calculated histogram distributions of various dynamical variables with those predicted by the rigid rotor-harmonic oscillator model. We also compared the distributions over rotational energies for a model of free SO2 molecule, and the mean energies transferred in SO2Ar collisions as calculated with the sampling of initial conditions by our method and by the Markov chain sampling procedure. The successive sampling method can be recommended for specifying initial conditions in studies of the collisional energy transfer under condition of local excitation.