BCC iron

[fgygi]

The electronic structure of BCC iron can be computed using Qbox 1.71.4 with the following input file:

Code: Select all

# BCC iron 
# a = 2.833 Ang = 5.3535962 Bohr PBE value from Haas et al, Phys. Rev. B79, 085104 (2009)
set cell 2.6768 2.6768 -2.6768  -2.6768 2.6768 2.6768  2.6768 -2.6768 2.6768 
set ref_cell 3.0 3.0 -3.0  -3.0 3.0 3.0  3.0 -3.0 3.0 
species iron Fe_ONCV_PBE-1.2.xml
atom Fe1 iron 0.00000 0.00000 0.00000
set nempty 8
set nspin 2
set ecut 110
set ecuts 100
set stress ON
set fermi_temp 1000
set xc PBE
kp6661bcc.i
set wf_dyn JD
randomize_wf 0.1
set scf_tol 1.e-9
set charge_mix_rcut 0
run 0 100 5 
partial_charge Fe1 2.0
partial_charge -spin 1 Fe1 2.0
partial_charge -spin 2 Fe1 2.0

The resulting magnetic moment is 2.07. Values reported in the literature range from 1.97 (OQMD Database http://oqmd.org/analysis/calculation/1938395 ) to 2.23 (Moroni et al, Phys. Rev. B56, 15629 (1997)).
The lattice constant used is a = 2.833 Å = 5.3535 Bohr, corresponding the the PBE value obtained by Haas et al, Phys. Rev. B 79, 085104 (2009). The residual stress is -0.68 GPa, indicating that the lattice constant is slightly larger than the equilibrium value. Note that more accurate results could be obtained by increasing the number of k-points used (6x6x6 mesh).