[Pw_forum] R: Re: HSE vs PBE

Giuseppe Mattioli giuseppe.mattioli at ism.cnr.it
Thu May 24 17:41:28 CEST 2012


> Do you mean that hybrid calcs can be performed only with Norm Conserving
> ones?

Yes, absolutely...:-( 

On Thursday 24 May 2012 16:16:27 giacsport at libero.it wrote:
> Dear Giuseppe,
>                           really thanks for the very clear and helpful
> reply.
> 
> But let me ask you this.
> 
> From the psesudo library of PWSCF I took  the
> 
> Cu.pbe-n-van.UPF  (hard to say...I dont find it anymore in the
> database....has the database been changed recently?...anyway the header of
> the pseudo is reported below)
> 
> pseudo that is a USPP one.
> 
> Do you mean that hybrid calcs can be performed only with Norm Conserving
> ones?
> 
> :'(
> 
> Thanks once more!
> 
> Best,
> Giacomo
> 
> 
> the pseudo header
> 
> <PP_INFO>
> Generated using Vanderbilt code, version   7  3
> 4
> Author: unknown    Generation date:    4    3
> 5
> Automatically converted from original
> format
>     1        The Pseudo was generated with a Scalar-Relativistic
> Calculation 2.00000000000E+00    Local Potential cutoff radius
> nl pn  l   occ               Rcut            Rcut US             E pseu
> 3D  3  2  9.50     10.00000000000      2.00000000000     -0.60492460120
> 4S  4  0  1.00     10.00000000000      2.10000000000     -0.43710222811
> 4P  4  1  0.50     10.00000000000      2.20000000000     -0.10740671642
> </PP_INFO>
> 
> 
> <PP_HEADER>
>    0                   Version Number
>   Cu                   Element
>    US                  Ultrasoft pseudopotential
>     T                  Nonlinear Core Correction
>  SLA  PW   PBE  PBE    PBE  Exchange-Correlation functional
>    11.00000000000      Z valence
>  -121.01063523375      Total energy
>   0.0000000  0.0000000 Suggested cutoff for wfc and rho
>     2                  Max angular momentum component
>   867                  Number of points in mesh
>     3    6             Number of Wavefunctions, Number of Projectors
>  Wavefunctions         nl  l   occ
>                        3D  2  9.50
>                        4S  0  1.00
>                        4P  1  0.50
> </PP_HEADER>
> 
> >----Messaggio originale----
> >Da: giuseppe.mattioli at ism.cnr.it
> >Data: 24/05/2012 11.27
> >A: "giacsport at libero.it"<giacsport at libero.it>, "PWSCF
> >Forum"<pw_forum at pwscf.
> 
> org>
> 
> >Ogg: Re: [Pw_forum] HSE vs PBE
> >
> >
> >Dear Giacomo
> >
> >> is it OK? can I do it? I.e., using PBE psudopotential for HSE
> >> calculations?
> >
> >A the present time, there is no other way to perform hybrid calculations
> >but
> 
> with GGA (norm
> 
> >conserving) pseudopotentials. In this regard, I suppose that a 95 Ry wfc
> 
> cutoff may be poor for
> 
> >copper (with semicore 3s and 3p). You should test the convergence of your
> >PBE
> 
> results before
> 
> >attempting HSE calculations.
> >
> >> and then use the same for HSE (same pseudopotentials at PBE, taken from
> >> the PwSCF website)
> >
> >I'm quite puzzled... There is no NC pseudopotential for copper in the
> 
> website. Do you mean the
> 
> >pslibrary?
> >
> >>     input_dft='hse', nqx1= 2, nqx2= 2, nqx3= 2,
> >
> >You should check the convergence of your results wrt the blend of k points
> 
> and q points, and this is
> 
> >the most painful task when using hybrid functionals (and metals are very
> 
> sensitive to k points...).
> 
> >In practice, be sure to the convergence of k points in the PBE
> >calculation,
> 
> and starting from
> 
> >nqx1= 1, nqx2= 1, nqx3= 1,
> >
> >try to reach convergence (or reach the most bloody-cpu-consuming grid you
> >can
> 
> afford) wrt the q
> 
> >points.
> >
> >> nspin=2
> >
> >Copper is nonmagnetic, and you have an even number of atoms. Save (a lot
> >of)
> 
> time with nspin=1.
> 
> >> nbnd = 80
> >> occupations='smearing'
> >
> >The latter provide already a fair number of unoccupied states, you do not
> 
> need to use the former.
> 
> >HTH
> >
> >Giuseppe
> >
> >On Thursday 24 May 2012 04:45:14 giacsport at libero.it wrote:
> >> Dear All,
> >> 
> >>             I am using the development version of PWscf.
> >> 
> >> I would like to ask you this question.
> >> 
> >> I want to make HSE hybrid calculations (vc-relax) using pseudopotential
> >> at PBE level.
> >> I want indeed test the impact of the hybrid functional in the lattice
> >> parameter (this is the case of Copper)
> >> 
> >> I mean is it a correct procedure to optimize the system with such
> >> initial settings
> >> 
> >> /
> >> &system
> >> 
> >>     ibrav=  2, celldm(1) = 6.830792531
> >>     nat=  4, ntyp= 1, nspin=2,
> >>     ecutwfc = 95.,  nbnd = 80, occupations='smearing',
> >>     degauss=0.01,smearing='gaussian', starting_magnetization(1)=1
> >> 
> >> /
> >> 
> >> and then use the same for HSE (same pseudopotentials at PBE, taken from
> >> the PwSCF website)
> >> 
> >> /
> >> &system
> >> 
> >>     ibrav=  2, celldm(1) = 6.830792531
> >>     nat=  4, ntyp= 1, nspin=2,
> >>     ecutwfc = 95.,  nbnd = 80, occupations='smearing',
> >>     degauss=0.01,smearing='gaussian', starting_magnetization(1)=1
> >>     input_dft='hse', nqx1= 2, nqx2= 2, nqx3= 2,
> >>     x_gamma_extrapolation = .TRUE.
> >> 
> >> /
> >> 
> >> is it OK? can I do it? I.e., using PBE psudopotential for HSE
> >> calculations?
> >> 
> >> 
> >> Thanks in advance for any suggestion!
> >> 
> >> Best,
> >> Giacomo
> 
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   Giuseppe Mattioli                            
   CNR - ISTITUTO DI STRUTTURA DELLA MATERIA   
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