[Pw_forum] offset

[Ngoc Linh Nguyen]

I think in this question you can figure it out by yourself.

Hint: with offset of kpoint, in your case, you can increase the number 
of k points in Brillouin  Zone. And the calculation for some quantities, 
such as Li absorption energy, will approach a convergence if the number 
of k points is increased.

Good luck,
Linh



raheleh vaziri wrote:
>
> Dear all,
>
>  
>
> I have two input files. The difference between these input files is 
> offset. Which of them is the best? Please find the attached input files.
>
>  I am pleased if you could tell me the criterion of the determination 
> of offset.
>
>  
>
> Thanks in advance.
>
>  
>
> &CONTROL
>
>   calculation  ="scf",
>
>   pseudo_dir   = "./",
>
>   outdir   = "./",
>
>   prefix   = "2",
>
> /
>
> &SYSTEM
>
>   ibrav= 4,
>
>   celldm(1) = 13.9452,
>
>   celldm(3) = 0.50220,
>
>   nat = 21,
>
>   ntyp= 2 ,
>
>   ecutwfc  = 25.0,
>
>   ecutrho = 105.0,
>
>   occupations='smearing', smearing='marzari-vanderbilt', degauss=0.05,
>
> /
>
> &electrons
>
>   diagonalization='cg',
>
>   conv_thr  = 1.0e-7,
>
>   mixing_beta = 0.5,
>
> /
>
> ATOMIC_SPECIES
>
> C  12.00   C.pw91-van_ak.UPF
>
> Li 6.914   Li.pw91-s-van_ak.UPF
>
> ATOMIC_POSITIONS {angstrom}   
>
>  C                 -2.31375055    5.60380930    1.97749928
>
>  C                  2.60873529    5.59894992    1.97827588
>
>  C                  1.37111491    4.88605088    1.98071055
>
>  C                  0.14749316    5.60138230    1.98026831
>
>  C                 -1.09012567    4.88849231    1.98354393
>
>  C                 -1.08523445    3.47114506    1.99210730
>
>  C                  3.83236102    4.88362824    1.98354902
>
>  C                  3.83725009    3.46629018    1.99363246
>
>  C                  2.59963288    2.75339819    1.99851730
>
>  C                  1.37600716    3.46871987    1.99324416
>
>  C                  0.13838997    2.75582789    1.99812899
>
>  C                  0.14327905    1.33848981    2.00821243
>
>  C                  5.06087580    2.75096849    1.99890559
>
>  C                  5.06576489    1.33363043    2.00898904
>
>  C                  3.82814767    0.62073845    2.01387388
>
>  C                  2.60452196    1.33606013    2.00860075
>
>  C                  1.36690476    0.62316813    2.01348557
>
>  C                  6.28939060    0.61830875    2.01426218
>
>  Li                 1.35277313    6.31968764    0.12525022
>
>  Li                -2.31676697    4.21513012    0.13346760
>
>  Li                 1.35260170    2.08833760    0.15666888
>
> K_POINTS {automatic}
>
> 2 2 5 0 0 0
>
> Or
>
> K_POINTS {automatic}
>
> 2 2 5 1 1 1
>
>  
>
> Mahkameh Vaziri
>
> physical chemistry department
>
> K.N.Toosi university of technology,Tehran,Iran.
>
>
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>
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 Nguyen Ngoc Linh, PhD Student
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