Effective Coulomb interaction in actinides from linear response approach*

The effective on-site Coulomb interaction (Hubbard U) between 5f electrons in actinide metals (Th-Cf) is calculated with the framework of density-functional theory (DFT) using linear response approach. The U values seldom rely on the exchange-correlation functional, spin-orbital coupling, and magnetic states, but depend on the lattice volume and actinide element. Along the actinide series, the Coulomb parameter U of α-phase first decreases slowly, followed by a jump in the vicinity of Pu and then a monotonous increase. For light actinides, the lattice volume has a sizeable influence on U while the localization of 5f electrons is almost constant. But for transplutonium metals, U is almost independent of the lattice volume but the electronic localization increases rapidly. The calculated lattice parameters from DFT+U with the Coulomb parameters as input are in better agreement with the experimental values than those from DFT within local density approximation or Perdew-Burke-Ernzerhof approximation for solids (PBEsol). In particular, the agreement between PBEsol+U and experiment is remarkable.