[Pw_forum] problems with vc-relax

WF windbellklbh at gmail.com
Fri Sep 9 01:35:08 CEST 2011


Is it good enough to relax an arbitrary system with only gamma k-points? I
thought it is necessary to do some test with k-points as this effect change
from system to system. In my experience, more k-points is necessary for a
metal-like system, i.e. graphene.

Best regards,

Wu, F

> Date: Thu, 8 Sep 2011 11:12:24 -0400
> From: xijunw at gmail.com
> To: pw_forum at pwscf.org
> Subject: Re: [Pw_forum] problems with vc-relax
> 
> On Thu, Sep 8, 2011 at 10:26 AM, Elie Moujaes
> <elie.moujaes at hotmail.co.uk> wrote:
> > Hello Xijun,
> 
> Hello Elie,
> 
> > I did not send the e-mail twice intentionally. There was a problem with
my
> > e-mail and it kept giving me an error about problems with Windows hotmai
> > hence why it was sent twice without me knowing except now when I opened
my
> > e-mail so I apologize for that. Also I wont include blank lines in the
input
> > file either.  Back to my calculations, I have restarted the
calculations, it
> > went fine at first but then I got the error:
> > from scale_h: not enough memory allocated for radial FFT; try restarting
> > with a larger cell_factor.
> 
> Check the manual for definition of cell_factor. The default value is
> 1.2, you could try a larger value.
> 
> What's your new K_POINTS setting? Since you are relax the system, I
> suggest you start from:
> 
>      K_POINTS {gamma}
> 
> This will far faster. and need far less memory.
> 
> > Another simple question: I realized when I restarted everything that the
> > positions of the atoms were the initial ones even before starting the
> > relaxation process where as the k-points used were the NEW ones. Is that
> > normal? or should I have substituted the the C atoms positions by the
most
> > recent ones then restart again?
> 
> Yes, restart again with NEW ATOMIC_POSITIONS and "restart_mode=
'from_scratch' "
> 
> Regards,
>  - Xijun
> 
> > Regards
> > Elie
> >
> >> Date: Wed, 7 Sep 2011 16:20:49 -0400
> >> From: xijunw at gmail.com
> >> To: pw_forum at pwscf.org
> >> Subject: Re: [Pw_forum] problems with vc-relax
> >>
> >> Hi, Elie,
> >>
> >> Please do not repeat sending the same message to the mail list. Also,
> >> people will be more happy to help you if you keep your mail neat by
> >> removing all the unnecessary blank lines in the input file.
> >>
> >> Regards,
> >> Xijun
> >>
> >> On Wed, Sep 7, 2011 at 3:28 PM, Elie Moujaes
<elie.moujaes at hotmail.co.uk>
> >> wrote:
> >> > Dear all,
> >> >
> >> >
> >> >
> >> > I am relaxing a 60 atom supercell (graphene grain boundary) to make
the
> >> > total force on atoms mainly 0.001 Ry/au. However the vc-relax stopped
> >> > after
> >> > 4 days of execution and without reaching the desired force threshold.
> >> > The
> >> > following output was obtained :
> >> >
> >> >
> >> >
> >> > 1st relaxation process:
> >> >
> >> >
> >> >
> >> > Total force 0.091   Pressure =- 114.1 kbar
> >> >
> >> >
> >> >
> >> > 2nd relaxation process:
> >> >
> >> >
> >> >
> >> > total force 0.1   Pressure = -55 kbar
> >> >
> >> >
> >> >
> >> > (new enthalpy < old enthalpy)
> >> >
> >> >
> >> >
> >> > 3rd process:
> >> >
> >> >
> >> >
> >> > total force = 0.058   pressure = -11 kbar
> >> >
> >> >
> >> >
> >> > Then in the 4th process, calculations stopped. Here are the last few
> >> > lines
> >> > of the output:
> >> >
> >> >
> >> >
> >> > iteration #  2     ecut=    36.75 Ry     beta=0.30
> >> >      Davidson diagonalization with overlap
> >> >      c_bands:  5 eigenvalues not converged
> >> >      c_bands:  1 eigenvalues not converged
> >> >      c_bands:  3 eigenvalues not converged
> >> >      c_bands:  1 eigenvalues not converged
> >> >      c_bands:  4 eigenvalues not converged
> >> >      c_bands:  4 eigenvalues not converged
> >> >      c_bands:  4 eigenvalues not converged
> >> >      c_bands:  4 eigenvalues not converged
> >> >      c_bands:  5 eigenvalues not converged
> >> >      c_bands:  5 eigenvalues not converged
> >> >      c_bands:  2 eigenvalues not converged
> >> >      c_bands:  2 eigenvalues not converged
> >> >      ethr =  2.90E-04,  avg # of iterations = 17.6
> >> >
> >> >      negative rho (up, down):  0.132E-01 0.000E+00
> >> >
> >> >      total cpu time spent up to now is 382283.13 secs
> >> >
> >> >      total energy              =    -676.77947904 Ry
> >> >      Harris-Foulkes estimate   =    -676.82846513 Ry
> >> >      estimated scf accuracy    <       0.17363554 Ry
> >> >
> >> >      iteration #  3     ecut=    36.75 Ry     beta=0.30
> >> >      Davidson diagonalization with overlap
> >> >      c_bands:  1 eigenvalues not converged
> >> >      c_bands:  1 eigenvalues not converged
> >> >      c_bands:  2 eigenvalues not converged
> >> >      c_bands:  3 eigenvalues not converged
> >> >
> >> >
> >> >
> >> > The input of the vc-relax is:
> >> >
> >> >
> >> >
> >> > &control
> >> >
> >> >     prefix='GBphonon',
> >> >
> >> >     calculation='vc-relax',
> >> >
> >> >     restart_mode='from_scratch',
> >> >
> >> >     tstress=.true.,
> >> >
> >> >     tprnfor=.true,
> >> >
> >> >     pseudo_dir =
> >> > '/exp/home/caiapo/emoujaes/espresso/espresso-4.3/Pseudo/',
> >> >
> >> >     outdir='/exp/home/caiapo/emoujaes/espresso/Moujaes-Results/',
> >> >
> >> >
> >> >
> >> >  /
> >> >
> >> >  &system
> >> >
> >> >     ibrav= 0, celldm(1) =1.889725989, nat=60, ntyp= 1, ecutwfc
> >> > =36.749309,
> >> > occupations='smearing', smearing='mp',degauss=0.01
> >> >
> >> > /
> >> >
> >> >  &electrons
> >> >
> >> >     conv_thr=1.D-6,
> >> >
> >> >     mixing_beta=0.3D0,
> >> >
> >> >     diago_david_ndim=2,
> >> >
> >> >
> >> >
> >> >  /
> >> >
> >> >
> >> >
> >> > &ions
> >> >
> >> >  ion_dynamics='bfgs'
> >> >
> >> >
> >> >
> >> > /
> >> >
> >> > $cell
> >> >
> >> > cell_dynamics='bfgs',
> >> >
> >> >
> >> >
> >> > /
> >> >
> >> >
> >> >
> >> > CELL_PARAMETERS (alat)
> >> >
> >> >   24.064488464   0.000772242   0.000000000
> >> >
> >> >    0.000000000   6.503051170   0.000000000
> >> >
> >> >    0.000000000   0.000000000   8.470514812
> >> >
> >> >
> >> >
> >> >
> >> >
> >> > ATOMIC_SPECIES
> >> >
> >> >  C  12.0107  C.blyp-mt.UPF
> >> >
> >> >
> >> >
> >> > ATOMIC_POSITIONS (angstrom)
> >> >
> >> > C      -11.330758616  -3.527803203   0.000000000
> >> >
> >> > C      -10.659793092  -1.160339161   0.000000000
> >> >
> >> > C      -12.039843315  -7.112619698   0.000000000
> >> >
> >> > C      -12.041158182  -5.732701936   0.000000000
> >> >
> >> > C      -10.941089654  -4.881442842   0.000000000
> >> >
> >> > ......
> >> >
> >> >
> >> >
> >> > Please can anyone advice me on this? Shall I start with the new
> >> > configuration and start relaxing again?
> >> >
> >> >
> >> >
> >> > Regards
> >> >
> >> >
> >> >
> >> > Elie Moujaes
> >> >
> >> > University of Nott
> >> >
> >> > University Park
> >> >
> >> > NGT 3RD
> >> >
> >> >
> >> >
> >> > _______________________________________________
> >> > Pw_forum mailing list
> >> > Pw_forum at pwscf.org
> >> > http://www.democritos.it/mailman/listinfo/pw_forum
> >> >
> >> >
> >>
> >>
> >>
> >> --
> >> Dept. of Chem and Biochem, Concordia University
> >> 7141 Sherbrooke Ouest, Montreal, QC, Canada (H4B 1R6)
> >> Tel: 514-848-2424-#5835 (Lab) TA office: SP175.23
> >> _______________________________________________
> >> Pw_forum mailing list
> >> Pw_forum at pwscf.org
> >> http://www.democritos.it/mailman/listinfo/pw_forum
> >
> > _______________________________________________
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> > Pw_forum at pwscf.org
> > http://www.democritos.it/mailman/listinfo/pw_forum
> >
> >
> 
> 
> 
> -- 
> Dept. of Chem and Biochem, Concordia University
> 7141 Sherbrooke Ouest, Montreal, QC, Canada (H4B 1R6)
> Tel: 514-848-2424-#5835 (Lab) TA office: SP175.23
> _______________________________________________
> Pw_forum mailing list
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-----------------------------------------------------------
Wu, F
College of Chemistry and Molecular Engineering, Peking University
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