Abstract
Simulations of the generation of the atomic polarization is necessary for
interpreting the second solar spectrum. For this purpose, it is important to
rigorously determine the effects of the isotropic collisions with neutral
hydrogen on the atomic polarization of the neutral atoms, ionized atoms and
molecules. Our aim is to treat in generality the problem of depolarizing
isotropic collisions between singly ionized atoms and neutral hydrogen in its
ground state. Using our numerical code, we computed the collisional
depolarization rates of the $p$-levels of ions for large number of values of
the effective principal quantum number $n^{*}$ and the Uns\"old energy $E_p$.
Then, genetic programming has been utilized to fit the available depolarization
rates. As a result, strongly non-linear relationships between the collisional
depolarization rates, $n^{*}$ and $E_p$ are obtained, and are shown to
reproduce the original data with accuracy clearly better than 10\%. These
relationships allow quick calculations of the depolarizing collisional rates of
any simple ion which is very useful for the solar physics community. In
addition, the depolarization rates associated to the complex ions and to the
hyperfine levels can be easily derived from our results. In this work we have
shown that by using powerful numerical approach and our collisional method,
general model giving the depolarization of the ions can be obtained to be
exploited for solar applications.