Scattering lengths for collisions of hydrogen and deuterium atoms

The scattering lengths for hydrogen and deuterium atoms interacting via the potentials of the X (1)Sigma(g)(+), b (3)Sigma(u)(+) and e (3)Sigma(u)(+) molecular. states are calculated. An estimate of the uncertainty in the X (1)Sigma(g)(+) scattering length arising from the coupling to the (1)Sigma(u)(+) states is made. The recommended scattering lengths are -0.67 and 148 bohr for the b (3)Sigma(u)(+) and e (3)Sigma(u)(+) interaction potentials, respectively, and 11.1 bohr for the X (1)Sigma(g)(+) interaction potential. It is suggested that deuterium atoms would be cooled efficiently by collisions with metastable hydrogen atoms.