[Pw_forum] R: Re: HSE vs PBE

[giacsport at libero.it]

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
>
>-- 
>********************************************************
>- Article premier - Les hommes naissent et demeurent
>libres et ègaux en droits. Les distinctions sociales
>ne peuvent être fondèes que sur l'utilitè commune
>- Article 2 - Le but de toute association politique
>est la conservation des droits naturels et 
>imprescriptibles de l'homme. Ces droits sont la libertè,
>la propriètè, la sùretè et la rèsistance à l'oppression.
>********************************************************
>
>   Giuseppe Mattioli                            
>   CNR - ISTITUTO DI STRUTTURA DELLA MATERIA   
>   v. Salaria Km 29,300 - C.P. 10                
>   I 00015 - Monterotondo Stazione (RM)          
>   Tel + 39 06 90672836 - Fax +39 06 90672316    
>   E-mail: <giuseppe.mattioli at ism.cnr.it>
>