Shape dependence of the deuteron radius

The expansion of the square of the ratio of the deuteron radius to the triplet neutron-proton scattering length is generalized to include the D-state component of the deuteron wave function. Although more than 98% of this ratio is independent of the potential model, the remainder is discussed in terms of the dependence on the deuteron D state and the nonlocality of the potential. The convergence for different expansion parameters, all of which can be directly obtained from experimental data, is investigated and an optimal choice is proposed.