Calculation of the paramagnetic susceptibility and specific heat in UGa 2 and UPd 2Al 3 from ab initio crystal field theory

Abstract

In the framework of the self-interaction corrected local density approximation, ab initio calculations have been carried out to obtain crystal field parameters for the paramagnetic state of UGa 2 and UPd 2Al 3. In two sets of calculations localized 5f states with occupation two and three, respectively, have been assumed. Using these parameters and adjusted anisotropic molecular field constants, the paramagnetic susceptibility for both compounds and the Schottky contribution to the specific heat in UPd 2Al 3 have been obtained by crystal field model calculations. Very good agreement between theoretical and experimental data is found for 5f 2 occupation in UGa 2. For UPd 2Al 3, the 5f 2 assumption yields qualitatively reasonable results as well, but it does not explain the T = 50 K maximum in the experimental data.