Rovibrational relaxation in collisions between H2 molecules:: I.: Transitions induced by ground state para-H2

We present the results of quantal calculations of cross sections and rate coefficients for rovibrational transitions in ortho- and para-H-2, induced by collisions with ground state para-H-2. Rovibrational levels up to (v, J) = (3,8) were included in the calculations, and rate coefficients are available for temperatures 100 less than or equal to T less than or equal to 6000 K. Comparison is made with previous calculations and with measurements of the rate coefficient for vibrational relaxation v = 1 --> 0. Agreement is found to be good at both high and low temperatures, but the measurements exceed the calculations at intermediate temperatures. Large discrepancies are found with previous calculations, which employed a semiclassical method.