[Pw_forum] geometry optimizaion-how to make it faster

[Stefano de Gironcoli]

On Mon, 23 Apr 2007, Sen wrote:

...
> --------
> Au  18.601360 16.000000   0.000000
> Au  18.601360 16.000000  54.570496
> ---------------
> --------------
> Au  15.451947 13.457026  81.183342
> -----------
> Au  17.718653 14.047231  80.089668
> -------------
> --------------
> S   15.998219 14.326591  31.279226
> C   16.001303 16.565260  33.968327
> H   17.675220 17.770269  33.820061
> H   14.330640 17.774763  33.819920
> ---------------
> The atomic positions are okay, however, the individual atom forcee are
> coming like this:
>     atom   1 type  1   force =     8.78530224    1.13988509  -14.03979912
>     atom   2 type  1   force =    12.01091279    1.31202407  -13.48731135
>     atom   3 type  1   force =     9.69708845   11.26363626   -5.68058137
>     atom   4 type  1   force =     9.72514514   11.34982112   -4.79680588
>     atom   5 type  1   force =    -2.54144525    8.89141511  -13.86762764
>     atom   6 type  1   force =    -3.12157312   11.70097423  -12.31860197
>     atom   7 type  1   force =    10.21942251    9.52077429   -0.85911975
>     atom   8 type  1   force =     9.81543682    9.46159249   -0.73870247
>     atom   9 type  1   force =    -1.32878929   12.88147452    2.62586847
>     atom  10 type  1   force =    -1.32982873   14.40215166    1.69396997
>     atom  11 type  1   force =   -13.51902374    6.88366314   -5.08150330
>     atom  12 type  1   force =   -13.53147027    6.74037823   -5.25299321
> ----and so on.
> I would greatly appreciate your valuable suggestions on what would be the
> most effecive way in handling such situations.
> Best regards,
> Sen

I would be very surprised if atomic positions that "are ok" produce such 
forces ...
which tyme of ATOMIC_POSITIONS have you chosen (alat, crystal, bohr, 
angstrom) ? the default is alat
If you have the xcrysden code installed you can visualize your structure
by giving the command
prompt> xcrysten --pwi your_input_file.in

Hope this helps

stefano

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