Calculational Study on the Compounds Np3M, Am3M, and on the System Pu-Am

Spin-polarized relativistic density functional theory has been employed for the study of the electronic and magnetic structures for the compounds Np{sub 3}M and Am{sub 3}M (M = Al; Ga; In) and their comparison with plutonium's alloys Pu{sub 3}M has been made. It has been found that of the three actinides (Np, Pu, Am) only plutonium has its FCC structure essentially more stable after alloying with aforementioned elements. Apart from that, the electronic and magnetic structures for the system Pu-Am presented by three different compounds: Pu{sub 3}Am, PuAm, and PuAm{sub 3} have been investigated. Their magnetic structures have been found to be too robust in comparison with the experimental fact that magnetism in Pu-Am system depends strongly on the percentage of the americium in the alloy. One possible explanation consists in the overestimation of the spin splitting and in the disregarding of orbital dependence of the exchange-correlation potential