[Pw_forum] relax question

[xu yuehua]

thanks for above  Mr Ding and Mr  Lan answers.
and another related question is  whether conv_thr  is in &ELECTRONS? is it
about scf ?
i don not understand how a flow chart when relaxing ions and its details?
 hope your kind help
2007/7/13, Ding Xunlei <dingxunlei at gmail.com>:
>
> Dear Yuehua,
>
> The default number is :
> etot_conv_thr=1.D-4
> forc_conv_thr=1.D-3
>
> So, 1. Your setting for forc_conv_thr= 1.D-6 is too small.
>        2. If you do need to set force like that, you need to set
> etot_conv_thr even smaller, saying 1.D-7.  And also, you need to set TRUE
> smaller than etot_conv_thr, saying 1.D-8.
>
> Hope it help.
>
> Yours sincerely,
> Ding
> 2007-07-13
> ______________________________________________
>
> ======= 2007-07-13 16:27:54 You have written: =======
>
> >hello all
> >i am doing relax.
> >in my inputfile,
> >i use  etot_conv_thr=1.D-6
> >  forc_conv_thr=1.D-6
> >and the output is
> >   atom   1 type  1   force =     0.00000290    0.00000095   -0.00000364
> >     atom   2 type  1   force =     0.00000081   -0.00000108
> 0.00000033
> >     atom   3 type  1   force =    -0.00000435   -0.00000425   -
> 0.00000160
> >     atom   4 type  1   force =    -0.00000312   -0.00000321   -
> 0.00000080
> >     atom   5 type  1   force =    - 0.00000446   -0.00000036   -
> 0.00000273
> >     atom   6 type  1   force =    -0.00000048    0.00000230
> 0.00000112
> >     atom   7 type  1   force =     0.00000164    0.00000118
> 0.00000060
> >     atom   8 type  1   force =     0.00000131   -0.00000040
> 0.00000145
> >     atom   9 type  2   force =    -0.00000362    0.00000154   -
> 0.00000201
> >     atom  10 type  2   force =    -0.00000029    0.00000191
> 0.00000302
> >     atom  11 type  2   force =     0.00000576   -0.00000134
> 0.00000194
> >     atom  12 type  2   force =     0.00000390    0.00000276
> 0.00000233
> >
> >Total force =     0.000015     Total SCF correction =     0.000054
> >     SCF correction compared to forces is too large, reduce conv_thr
> >
> >     The maximum number of steps has been reached.
> >my qustion is ,force at every atom is ok ,but why  the program asks to
> >reduce conv_thr
> >my conv_thr is not enough small ?
> >or my total relax step (50) is not adequate?
> >is there any principle about these parameter?
> >need your help
> >thanks a lot
> >--
> >Xu Yuehua
> >physics Department of Nanjing university
> >China
> >
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> >Pw_forum at pwscf.org
> >http://www.democritos.it/mailman/listinfo/pw_forum
> >
>
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>
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-- 
Xu Yuehua
physics Department of Nanjing university
China
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