Quantum calculations of H$_2$--H$_2$ collisions: from ultracold to thermal energies*

We present quantum dynamics of rotational and vibrational energy transfer in collisions between two para-H$_2$ molecules over a wide range of energies spanning the ultracold limit to thermal energies. The calculations were carried out using a quantum scattering code [1] that solves the time-independent Schr\"odinger equation in its full-dimensionality without any angular momentum decoupling approximations. The sensitivity of the results to details of the interaction potential as well as the initial vibrational and rotational quantum numbers of the H$_2$ molecules is explored. Cross sections and rate coefficients for elastic and inelastic collisions from our calculations are compared with available experimental and theoretical results [2,3].\\ References: [1] R. V. Krems, TwoBC - quantum scattering program, University of British Columbia, Vancouver, Canada (2006); [2] G. Qu\'em\'ener, N. Balakrishnan, and R. V. Krems, Phys. Rev. A {\bf 77}, 030704(R) (2008); [3] G. Qu\'em\'ener and N. Balakrishnan, arXiv:0812.3866 (accepted in J. Chem. Phys.).