[QE-users] Question about optimizing the lattice constant of iron

[David Foster]

HiI think it is good enough with nearly 1% error.

Regards
 
 David 

    On Tuesday, December 25, 2018, 7:06:01 AM GMT+3:30, Gui Wei <201707021019 at cqu.edu.cn> wrote:  
 
 Hi, When optimizing the lattice constant of bcc Fe,the result is a=2.830A， which is in disagreement with experimentally derived structural parameter a=2.863A.Could someone give me some advice?
&CONTROL    calculation = 'vc-relax'    prefix='Fe1',    pseudo_dir = '/public/home/duan1/gw2/pseudo/',    outdir='/public/home/duan1/gw2/tempdir/'    tprnfor     = .true.    tstress     = .true./&SYSTEM    ibrav= 1,     A=2.8664    nat= 2     ntyp= 1    occupations='smearing',    smearing='mp',    degauss=0.02,    ecutwfc =37    ecutrho =240    nspin   = 2    starting_magnetization(1) = 0.4/&ELECTRONS    conv_thr        = 1.0d-8    mixing_beta      = 0.7/&IONS   ion_dynamics = 'bfgs'/&CELL   cell_dynamics = 'bfgs' / ATOMIC_SPECIESFe  55.847  Fe.pbe-n-kjpaw_psl.0.2.4.UPFATOMIC_POSITIONS crystal Fe   0.0000000000000000   0.0000000000000000   0.0000000000000000 Fe   0.5000000000000001   0.5000000000000001   0.5000000000000001K_POINTS automatic8  8  8  0  0  0
The result: CELL_PARAMETERS (alat=  5.41671099)   0.987418499   0.000000000   0.000000000   0.000000000   0.987418499   0.000000000   0.000000000   0.000000000   0.987418499


Gui WeiSchool of Mechanical Engineering，Chongqing University, China
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