[Pw_forum] ecut dependence of symmetry operations(?)

[Madhura Marathe]

 Thanks Kun Yin and Lorenezo.

 I checked the output files and saw the warnings related to FFT at the
start of the output file for which I get less number of symmetry
operations.

 Best wishes for new year,
 Madhura.

> Quoting Madhura Marathe :
>>  Dear all,
>>
>>  While performing convergence calculations w.r.t energy cut-off for a
>> bulk
>> system, I found that the number of symmetry operations detected by a
>> code
>> is different depending on the value of ecut. This is very surprising
>> because for the same system, the symmetries should not depend on the
>> ecut
>> value.
>
>
> Dear Madhura,
> your question is the complementary one to a Frequentedly-Asked
> Question (FAQ), when the code suppresses some symmetry operation
> because they are incompatible with the FFT grid a warning is issued.
> See this page  for
> more details.
>
> regards
>
>
>
> --
> Lorenzo Paulatto
>
> formerly at:
> SISSA  &  DEMOCRITOS (Trieste)
> skype: paulatz
> www:   http://people.sissa.it/~paulatto/
>
>   *** save italian brains ***
>http://saveitalianbrains.wordpress.com/
>
>
> 
>SISSA Webmail https://webmail.sissa.it/
>Powered by Horde http://www.horde.org/
>
>
> ___
> Pw_forum mailing list
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>


-- 
Madhura Marathe,
PhD student, TSU,
JNCASR, Bangalore.
India.
Phone No: +91-80-22082835

[Pw_forum] ecut dependence of symmetry operations(?)

[kyin.cn]

This maybe relate with FFT grid. Try to specify parameters 'nr' in inputfile. 
You can get the reference value by executing this command in outputfile of ecut 
=20,25,...
$grep 'FFT grid:' ***.out

Kun Yin, PhD student
Nanjing University, China
2010-01-05 



kyin.cn 



 Madhura Marathe 
? 2010-01-05  12:37:30 
 pw_forum 
??? 
??? [Pw_forum] ecut dependence of symmetry operations(?) 
 
 Dear all,
 While performing convergence calculations w.r.t energy cut-off for a bulk
system, I found that the number of symmetry operations detected by a code
is different depending on the value of ecut. This is very surprising
because for the same system, the symmetries should not depend on the ecut
value.
 For Ecut = 20, 25, 40, 50 and 55 Ry, the output says -
"24 Sym.Ops. (with inversion)";
whereas for ecut = 30, 35, 45 and 60 Ry, the output is -
"12 Sym.Ops. (no inversion)"
 I have performed the same calculations using versions 4.0.4 and 4.1 with
the same results.
The input file is as follows -
*
 &control
calculation = 'scf'
verbosity = 'high'
restart_mode = 'from_scratch',
prefix = 'RuGGA',
tstress=.true.
tprnfor=.true.
pseudo_dir = '/home/madhura-data/pseudo/',
outdir = '/home/madhura-data/tmp/'
/
 &system
ibrav = 4, celldm(1) = 5.1831, celldm(3) = 1.584,
nat = 2, ntyp = 1,
ecutwfc = 20, ecutrho = 160, # ecutrho = 8*ecutwfc
occupations='smearing', smearing='mp',degauss=0.05
nbnd = 20
/
 &electrons
diagonalization = 'david', mixing_mode = 'plain',
mixing_beta = 0.7, conv_thr = 1.0d-12
/
ATOMIC_SPECIES
 Ru 101.07 Ru.pbe-n-van.UPF
ATOMIC_POSITIONS {crystal}
 Ru 0.00   0.00   0.00
 Ru 0.6667 0. 0.50
K_POINTS automatic
 8 8 8 0 0 0
*
 Can anybody explain what is happening? Or do I need to file a bug report?
Because except for this problem, energies and stress values seem to be
converging.
 Thanks and regards,
 Madhura.
-- 
Madhura Marathe,
PhD student, TSU,
JNCASR, Bangalore.
India.
Phone No: +91-80-22082835
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[Pw_forum] ecut dependence of symmetry operations(?)

[Lorenzo Paulatto]

Quoting Madhura Marathe :
>  Dear all,
>
>  While performing convergence calculations w.r.t energy cut-off for a bulk
> system, I found that the number of symmetry operations detected by a code
> is different depending on the value of ecut. This is very surprising
> because for the same system, the symmetries should not depend on the ecut
> value.


Dear Madhura,
your question is the complementary one to a Frequentedly-Asked  
Question (FAQ), when the code suppresses some symmetry operation  
because they are incompatible with the FFT grid a warning is issued.  
See this page  for  
more details.

regards



-- 
Lorenzo Paulatto

formerly at:
SISSA  &  DEMOCRITOS (Trieste)
skype: paulatz
www:   http://people.sissa.it/~paulatto/

  *** save italian brains ***
   http://saveitalianbrains.wordpress.com/



   SISSA Webmail https://webmail.sissa.it/
   Powered by Horde http://www.horde.org/

[Pw_forum] ecut dependence of symmetry operations(?)

[Madhura Marathe]

 Dear all,

 While performing convergence calculations w.r.t energy cut-off for a bulk
system, I found that the number of symmetry operations detected by a code
is different depending on the value of ecut. This is very surprising
because for the same system, the symmetries should not depend on the ecut
value.

 For Ecut = 20, 25, 40, 50 and 55 Ry, the output says -
"24 Sym.Ops. (with inversion)";
whereas for ecut = 30, 35, 45 and 60 Ry, the output is -
"12 Sym.Ops. (no inversion)"

 I have performed the same calculations using versions 4.0.4 and 4.1 with
the same results.
The input file is as follows -
*
 &control
calculation = 'scf'
verbosity = 'high'
restart_mode = 'from_scratch',
prefix = 'RuGGA',
tstress=.true.
tprnfor=.true.
pseudo_dir = '/home/madhura-data/pseudo/',
outdir = '/home/madhura-data/tmp/'
/
 &system
ibrav = 4, celldm(1) = 5.1831, celldm(3) = 1.584,
nat = 2, ntyp = 1,
ecutwfc = 20, ecutrho = 160, # ecutrho = 8*ecutwfc
occupations='smearing', smearing='mp',degauss=0.05
nbnd = 20
/
 &electrons
diagonalization = 'david', mixing_mode = 'plain',
mixing_beta = 0.7, conv_thr = 1.0d-12
/
ATOMIC_SPECIES
 Ru 101.07 Ru.pbe-n-van.UPF
ATOMIC_POSITIONS {crystal}
 Ru 0.00   0.00   0.00
 Ru 0.6667 0. 0.50
K_POINTS automatic
 8 8 8 0 0 0
*

 Can anybody explain what is happening? Or do I need to file a bug report?
Because except for this problem, energies and stress values seem to be
converging.

 Thanks and regards,
 Madhura.

-- 
Madhura Marathe,
PhD student, TSU,
JNCASR, Bangalore.
India.
Phone No: +91-80-22082835

[Pw_forum] internal parameter 'u'

[kajal jindal]

Hii,

I want to know that how can I determine the value of internal parameter
'u',which characterizes the length of the bond parallel to c-axis, in
hexagonal wurtzite structure ..

thanks in advance,

sincerely,
Miss Kajal
(UTA)(University of Delhi)
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