Rotational excitation of HD molecules by He atoms

We present rate coefficients for rotational transitions induced in collisio ns between HD and He. Rotational levels and kinetic temperatures T less tha n or equal to 1000 K are considered. The interaction potential surface calc ulated by Muchnick & Russek (1994) has been used, together with the quantal coupled-channel method for calculating the cross-sections. Very good agree ment with previous calculations by Schaefer (1990) is obtained. The present work goes beyond the latter in that collision rates are calculated for all available rotational levels below the first excited vibrational level.