Electron correlation effect versus spin–orbit coupling for tungsten and impurities

Abstract

The electron correlation and spin-orbit coupling (SOC) effects are investigated for body-centered-cubic tungsten and intrinsic & irradiative impurities using first principles calculations based upon the density functional theory. It is found that the electron correlation between the localized 5d electrons and the SOC effect are significant in modifying the band structures and the formation energies of defects. For the latter one, the involving of electron correlation always makes the defects stabler than the Perdew-Burke-Ernzerhof results, while the SOC contributes diversely for different defects. Moreover, the migration barrier of single tungsten vacancy moving in 111 direction is explored, where the inclusion of electron correlations remarkably decreases the migration barrier, while the influence of SOC is almost negligible. This study can help to validate the previous studies on irradiative defects in tungsten and improve the further investigations.

First principles investigation of electron correlation and Lifshitz transition within iron polynitrides

“…Within this scheme, the U and J are derived from the Slater integrals, which are obtained from the charge densities by approximating the isotropic screened Coulomb interaction in a form of Yukawa potential. The validation of this scheme has been examined in several works [35,39,40]. The achieved results of U and J for iron polynitrides are listed in table 1.…”

Multilayer interface tracking model of pure tungsten oxidation

“…The term of E dc [n σ i ] is a 'double counting' term, which is included because when we additively append the Hubbard term E Hub [n σ i ], the energy contribution of the related orbitals has already been counted in the DFT term. In our calculations we use a Coulomb interaction parameter of LDAUU = 1.82 eV for pure metal W [61] because it does not affect the distribution of electrons for the attempt frequency calculations. However, we have also repeated the calculations with a value of LDAUU = 6.2 eV used for WO 3 [62] and found only a change of 5% in the migration energy barriers.…”

“…Tungsten is a transition metal with partially-filled d orbitals that requires special DFT treatments. Here we use the DFT+U technique with the parameterization for W used by Feng et al [62]. The generalized gradient approximation (GGA) and Perdew-Burke-Ernzerhof (PBE) was applied to build the pseudopotential of the system and the frozen-core convention was implemented with the projectoraugmented wave (PAW) method.…”