  In the evaluation of weak interacting massive particles (WIMPs) detection
rates, the WIMP-nucleus cross section is commonly described by using form
factors extracted from charge distributions. In this work, we use different
proton and neutron distributions taken from Hartree-Fock calculations. We study
the effects of this choice on the total detection rates for six nuclei with
different neutron excess, and taken from different regions of the nuclear
chart. The use of different distributions for protons and neutrons becomes more
important if isospin-dependent WIMP-nucleon interactions are considered. The
need of distinct descriptions of proton and neutron densities reduces with the
lowering of the detection energy thresholds.
