[QE-users] electric field

[Stefano Baroni]

that’s because macroscopic polarization is a property of insulators ... SB

___
Stefano Baroni, Trieste -- http://stefano.baroni.me

> On 16 Sep 2018, at 10:42, Sabike Ghasemi <s.ghasemi at du.ac.ir> wrote:
> 
> thank you for reply,
> but when ocupation = smearing then i face wiht an error:
>  Berry Phase/electric fields only for insulators!
> 
> From: "Stefano Baroni" <baroni at sissa.it>
> To: "Quantum Espresso users Forum" <users at lists.quantum-espresso.org>
> Sent: Saturday, urself September 15, 2018 12:10:26 PM
> Subject: Re: [QE-users] electric field
> 
> Not sure, but it seems to me that “occupations=‘fixed’” makes the code assume that the system is an insulator, so that it does not search any Fermi energy. That keyword is somewhat clashing with the “degauss” and “smearing” keywords. Do not know exactly what the code does in this case, but there is something you have to clean up in your input file and, possibly, in your understanding of the code. Also, we usually love to see the name and affiliation of those who post to this forum. Best wishes — Stefano B
> 
> On 15 Sep 2018, at 01:21, Sabike Ghasemi <s.ghasemi at du.ac.ir> wrote:
> 
> hello
> i want to apply electric field to bilayer graphene. i am confused why do not have my output fermi energy?
> input is :
> 
>  &CONTROL
>                  calculation = 'scf' ,
>                 restart_mode = 'from_scratch' ,
>                   wf_collect = .true. ,
>                       outdir = './out' ,
>                       wfcdir = './out' ,
>                   pseudo_dir = './' ,
>                    verbosity = 'high' ,
>                etot_conv_thr = 1.0D-6 ,
>                forc_conv_thr = 1.0D-2 ,
>                      tstress = .true. ,
>                 tprnfor = .true. ,
>  lelfield=.true., 
>  nberrycyc=3 ,
>  gdir=3 , 
> nppstr=1 ,
>  /
>  &SYSTEM
>                        ibrav = 4,
>                    celldm(1) = 4.511848446,
>                    celldm(3) = 9.462870616,
>                          nat = 4,
>                         ntyp = 1,
>                      ecutwfc = 30 ,
>                      ecutrho = 180 ,
>                            input_dft = 'vdW-DF' ,
>                  occupations = 'fixed' ,
>                      degauss = 0.02 ,
>                     smearing = 'methfessel-paxton' , 
>                         
>  /
>  &ELECTRONS
>             electron_maxstep = 200,
>                     conv_thr = 1.0D-6 ,
>                  startingwfc = 'atomic+random' ,
>                  mixing_beta = 0.3 ,
>   diagonalization = 'cg' ,
> efield_cart(1) = 0.d0,
>               efield_cart(2) = 0.d0,
>               efield_cart(3) = 0.019447d0,
>   /
> 
> ATOMIC_SPECIES
>     C   12.00000  C.blyp-mt.UPF 
> ATOMIC_POSITIONS (crystal)
> C        0.333333330   0.666666660   0.572649573    
> C        1.000000000   0.000000000   0.572649573    
> C        0.666666660   0.333333330   0.427350427    
> C        1.000000000   0.000000000   0.427350427     
> K_POINTS automatic 
>   12 12 1   0 0 0 
> 
> please help me.
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> — 
> Stefano Baroni - Trieste —  http://stefano.baroni.me 
> 
> 
> 
> 
> 
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