[Pw_forum] force

lan haiping lanhaiping at gmail.com
Thu Aug 20 20:35:19 CEST 2009


Dear Ali :

 What the  force thread you set for the unit cell ? i.e,
forc_conv_thr .   The values you posted here are quite close to the default
setting , 1.0D-3.  Therefore,   You can run ion-relaxation to satisfy
yourself, whichi i think is not a  computation burden.

If you have built your unitcell system with  satisfied accuaray, there is no
reason to make cell relation for a supercell.


Regards,
On Thu, Aug 20, 2009 at 11:11 PM, ali kazempour <kazempoor2000 at yahoo.com>wrote:

> Dear
> I use vc-relax to optimize the lattice constant and also the position for
> bulk. After I make supercell with these optimized value and run a scf with
> similar value as bulk. But the force as I listed below for some atom is
> relatively more than other. Is it good for force or should I do again
> vc-relax for supercell?
> Forces acting on atoms (Ry/au):
>
>      atom   1 type  1   force =     0.00000000    0.00000000    0.00000000
>      atom   2 type  1   force =     0.00000000    0.00000000    0.00000000
>      atom   3 type  1   force =     0.00000000    0.00000000    0.00000000
>      atom   4 type  1   force =     0.00000000    0.00000000    0.00000000
>      atom   5 type  1   force =     0.00000000    0.00000000    0.00020439
>      atom   6 type  1   force =     0.00000000    0.00000000    0.00020567
>      atom   7 type  1   force =     0.00000000    0.00000000    0.00020567
>      atom   8 type  1   force =     0.00000000    0.00000000    0.00020315
>      atom   9 type  1   force =     0.00000000    0.00000000   -0.00020439
>      atom  10 type  1   force =     0.00000000    0.00000000   -0.00020567
>      atom  11 type  1   force =     0.00000000    0.00000000   -0.00020567
>      atom  12 type  1   force =     0.00000000    0.00000000   -0.00020315
>      atom  13 type  1   force =    -0.00000152   -0.00000152   -0.00019723
>      atom  14 type  1   force =     0.00000136   -0.00000136   -0.00019719
>      atom  15 type  1   force =    -0.00000136    0.00000136   -0.00019719
>      atom  16 type  1   force =     0.00000152    0.00000152   -0.00019723
>      atom  17 type  1   force =    -0.00000186   -0.00000186    0.00000000
>      atom  18 type  1   force =     0.00000137   -0.00000137    0.00000000
>      atom  19 type  1   force =    -0.00000137    0.00000137    0.00000000
>      atom  20 type  1   force =     0.00000186    0.00000186    0.00000000
>      atom  21 type  1   force =    -0.00000152   -0.00000152    0.00019723
>      atom  22 type  1   force =     0.00000136   -0.00000136    0.00019719
>      atom  23 type  1   force =    -0.00000136    0.00000136    0.00019719
>      atom  24 type  1   force =     0.00000152    0.00000152    0.00019723
>      atom  25 type  2   force =    -0.00126659   -0.00126659    0.00000000
>      atom  26 type  2   force =    -0.00126600   -0.00126594    0.00000000
>      atom  27 type  2   force =    -0.00126594   -0.00126600    0.00000000
>      atom  28 type  2   force =    -0.00126811   -0.00126811    0.00000000
>      atom  29 type  2   force =    -0.00120604   -0.00120604    0.00011420
>      atom  30 type  2   force =    -0.00120546   -0.00120538    0.00011547
>      atom  31 type  2   force =    -0.00120538   -0.00120546    0.00011547
>      atom  32 type  2   force =    -0.00120536   -0.00120536    0.00011440
>      atom  33 type  2   force =    -0.00120604   -0.00120604   -0.00011420
>      atom  34 type  2   force =    -0.00120546   -0.00120538   -0.00011547
>      atom  35 type  2   force =    -0.00120538   -0.00120546   -0.00011547
>      atom  36 type  2   force =    -0.00120536   -0.00120536   -0.00011440
>      atom  37 type  2   force =     0.00126811    0.00126811    0.00000000
>      atom  38 type  2   force =     0.00126594    0.00126600    0.00000000
>      atom  39 type  2   force =     0.00126600    0.00126594    0.00000000
>      atom  40 type  2   force =     0.00126659    0.00126659    0.00000000
>      atom  41 type  2   force =     0.00120536    0.00120536    0.00011440
>      atom  42 type  2   force =     0.00120538    0.00120546    0.00011547
>      atom  43 type  2   force =     0.00120546    0.00120538    0.00011547
>      atom  44 type  2   force =     0.00120604    0.00120604    0.00011420
>      atom  45 type  2   force =     0.00120536    0.00120536   -0.00011440
>      atom  46 type  2   force =     0.00120538    0.00120546   -0.00011547
>      atom  47 type  2   force =     0.00120546    0.00120538   -0.00011547
>      atom  48 type  2   force =     0.00120604    0.00120604   -0.00011420
>      atom  49 type  2   force =    -0.00120811    0.00120812   -0.00010994
>      atom  50 type  2   force =    -0.00120609    0.00120609   -0.00011010
>      atom  51 type  2   force =    -0.00120474    0.00120474   -0.00011334
>      atom  52 type  2   force =    -0.00120812    0.00120811   -0.00010994
>      atom  53 type  2   force =    -0.00126901    0.00126929    0.00000000
>      atom  54 type  2   force =    -0.00126831    0.00126831    0.00000000
>      atom  55 type  2   force =    -0.00126875    0.00126875    0.00000000
>      atom  56 type  2   force =    -0.00126929    0.00126901    0.00000000
>      atom  57 type  2   force =    -0.00120811    0.00120812    0.00010994
>      atom  58 type  2   force =    -0.00120609    0.00120609    0.00011010
>      atom  59 type  2   force =    -0.00120474    0.00120474    0.00011334
>      atom  60 type  2   force =    -0.00120812    0.00120811    0.00010994
>      atom  61 type  2   force =     0.00120812   -0.00120811   -0.00010994
>      atom  62 type  2   force =     0.00120474   -0.00120474   -0.00011334
>      atom  63 type  2   force =     0.00120609   -0.00120609   -0.00011010
>      atom  64 type  2   force =     0.00120811   -0.00120812   -0.00010994
>      atom  65 type  2   force =     0.00126929   -0.00126901    0.00000000
>      atom  66 type  2   force =     0.00126875   -0.00126875    0.00000000
>      atom  67 type  2   force =     0.00126831   -0.00126831    0.00000000
>      atom  68 type  2   force =     0.00126901   -0.00126929    0.00000000
>      atom  69 type  2   force =     0.00120812   -0.00120811    0.00010994
>      atom  70 type  2   force =     0.00120474   -0.00120474    0.00011334
>      atom  71 type  2   force =     0.00120609   -0.00120609    0.00011010
>      atom  72 type  2   force =     0.00120811   -0.00120812    0.00010994
>
>      Total force =     0.012066     Total SCF correction =     0.000257
>
>
>      entering subroutine stress ...
>
>           total   stress  (Ry/bohr**3)                   (kbar)     P=
> -90.60
>   -0.00062585   0.00000003   0.00000000        -92.07      0.00      0.00
>    0.00000003  -0.00062585   0.00000000          0.00    -92.07      0.00
>    0.00000000   0.00000000  -0.00059589          0.00      0.00    -87.66
>
> thanks a lot
>
> Ali Kazempour
> Physics department, Isfahan University of Technology
> 84156 Isfahan, Iran. Tel-1: +98 311 391 3733
> Fax: +98 311 391 2376 Tel-2: +98 311 391 2375
>
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>


-- 
Hai-Ping Lan
Department of Electronics ,
Peking University , Bejing, 100871
lanhaiping at gmail.com, hplan at pku.edu.cn
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