Abstract
We study the depolarization of the p-states of the Mg, Ca, and Ba atoms by isotropic collisions with neutral hydrogen. We show that the main source of error in calculating the collisional depolarization is the inaccuracy of the interaction potentials. To better investigate this problem, we determine the region of the interaction potential that is decisive in the calculation of the depolarization rates. We conclude that semiclassical and quantum potentials should be combined in view of obtaining the so-called hybrid potentials, which are the most precise ones. The depolarization rates of the p-states of the Ca I, Mg I, and Ba I are inferred by using hybrid potentials and compared to previously obtained quantum and semiclassical rates. Insights are also given for treating the effects of the spin. Our results should be useful for interpreting the second solar spectrum.