||
关注:
1) 理论计算前需保持的良好习惯,如检验所选赝势的可靠性等
2) 经典文献所选赝势的摘录
PHYSICAL REVIEW B 85, 064110 (2012)
All total energy calculations were carried out within the
framework of DFT25,26 based on the frozen core all-electron
projector-augmented wave (PAW) method,27,28 as implemented
in the VASP code.29,30
The spin-polarized GGA was
employed, and the exchange-correlation energy of electrons
was parameterized by the Perdew-Burke-Ernzerhof (PBE)
functional.31
A kinetic energy cutoff of 500 eV was used for
the plane wave basis set, and the electronic self-consistency
convergence was set to 10−6 eV for all calculations.
Integrations
over reciprocal space were performed on an automatically
generated Monkhorst-Pack grid,32 which includes at least
18 nonequivalent k points in the irreducible Brillouin zone for
cubic phases, and more than 32-48 nonequivalent k points
for cotunnite and other noncubic phases.
Lattice parameters
and atomic positions that cannot be fixed by symmetry were
fully optimized at fixed volumes, with a Hellmann-Feynman
force tolerance less than 2 × 10−3 eV/°A for all structures of
Z = 1-4, and 2 × 10−2 eV/A° for Z = 8 structures (Pbca and
P1121/a in the Supplementary Material33). To improve the
convergence of integration over reciprocal space we adopted
the smearing scheme of tetrahedron method with Bl¨ochl
corrections,34 which is fairly accurate.
For all calculations, electrons of 6s26p65f 36d7s2 for uranium, 6s26p65f 67s2 for plutonium, and 2s22p4 for oxygen were treated as valence configurations.
The on-site Coulomb interaction among localized 5f electrons of uranium and plutonium atoms was described by a Hubbard U term, after
the DFT+U scheme introduced by Anisimov et al.35–38
This method has proved successful in capturing the band
structural features of strongly correlated systems.
In all
DFT+U calculations, we adopted the Dudarev version,38 and
set the semi-empirical parameters U = 4.5 eV, J = 0.51 eV
for UO2 and U = 4 eV, J = 0.7 eV for PuO2, which have
been extensively checked by many authors.7,39–
Archiver|手机版|科学网 ( 京ICP备07017567号-12 )
GMT+8, 2024-9-2 16:15
Powered by ScienceNet.cn
Copyright © 2007- 中国科学报社