Ab initio calculation of electronic structure and electric field gradient in Pu3Sn and PuSn3

The ground-state equilibrium properties, electronic structure and the electric field gradient (EFG) of Pu3Sn and PuSn3 are studied using density functional theory in the presence and in the absence of spin-orbit coupling (SOC). The calculated lattice parameter of PuSn3 (paramagnetic) and Pu3Sn (assumed to be ferromagnetic) in the presence of SOC are in good agreement with experimental values. The results for the electronic density of states (DOS) of Pu3Sn and PuSn3 show that the Fermi level is situated in a 'pseudogap', similar to what has been found for the PuTe system. The most striking feature in DOS of Pu3Sn is the presence of a gap at the interval from -6.5 eV to -4.2 eV, which is absent in the DOS of PuSn3. Also we found that there is a strong hybridization between Pu 6d and Sn 5p orbitals in both compounds and the main effect of spin polarization is to push the occupied 5f and 6d states to lower energies. Furthermore EFG and the effect of pressure on it is calculated both for PuSn3 and Pu3Sn and it is found that in both of them the EFG increases with pressure