  We have investigated the magnetic properties of Fe, Co, and Ni at finite
temperatures on the basis of the first-principles dynamical coherent potential
approximation (CPA) in order to clarify the role of the exchange interaction
energy ($J$) screened by {\it sp} electrons and its applicability to
finite-temperature magnetism. With use of the atomic $J$, we obtained the Curie
temperatures ($T_{\rm C}$) 1930 K for Fe and 2550 K for fcc Co, which are
overestimated by a factor of 1.8 as compared with the experimental values,
while we obtained $T_{\rm C}=620$ K for Ni being in good agreement with the
experiment. Calculated effective Bohr magneton numbers also quantitatively
agree with the experimental values. By comparing the results with those
obtained by the screened $J$ and by comparing them with the experiments, we
found that the screened $J$, which are reduced by 30% as compared with the
atomic ones, improve the ground-state magnetizations and densities of states at
low temperatures in Fe and fcc Co, as well as $T_{\rm C}$ in fcc Co. But the
screened $J$ yield worse results for finite temperature properties of Fe and
underestimate both the ground-state magnetization and $T_{\rm C}$ in case of
Ni. We discuss possible origins for these inconsistencies.
