Dear Mostafa,
It happens to be that my research is focused on molecules in ultrahigh electric 
fields such as 1Ry or higher. The SCF calculations exhibit positive total 
energies in oscillations. My problem is how to get those calculations converged 
with your help. Do you or anyone have ideas to resolve this problem?


When I use option of occupations = 'smearing' , the calculations stop and 
complain that "Error in routine iosys(1): Berry Phase/electric fields only for 
insulators!". Do you have any ideas to crack this problem? What parameters 
should I specify?


Thank you very much!


Jibiao Li


&CONTROL
                 calculation = 'scf' ,
                restart_mode = 'from_scratch' ,
                      outdir = '/home/jibiao/Calc/molecules/N2/' ,
                  pseudo_dir = '/home/jibiao/Codes/pseudo/' ,
                      prefix = 'N2' ,
                     tstress = .true. ,
                     tprnfor = .true. ,
                    lelfield = .true. ,
 /
 &SYSTEM
                       ibrav = 1,
                   celldm(1) = 15.117815022,
                         nat = 2,
                        ntyp = 1,
                     ecutwfc = 29 ,
                     ecutrho = 180 ,
                 occupations = 'fixed' ,
 /
 &ELECTRONS
            electron_maxstep = 300,
                 mixing_beta = 0.2D0 ,
             diagonalization = 'david' ,
              efield_cart(1) = 1,
              efield_cart(2) = 0,
              efield_cart(3) = 0,
 /
ATOMIC_SPECIES
    N   14.00700  N.pbe-van_ak.UPF
ATOMIC_POSITIONS angstrom
    N      5.122061326    3.999999675    4.000000376    
    N      4.000000000    4.000000000    4.000000000    0  0  0
K_POINTS automatic
  1 1 1   0 0 0






------------------ Original ------------------
From:  "Mostafa Youssef";<mostafa.yous...@aucegypt.edu>;
Date:  Tue, Aug 8, 2017 11:44 PM
To:  "pw_forum"<pw_forum@pwscf.org>; 

Subject:  Re: [Pw_forum] SCF calculations for molecules in electric fieldsare 
not converged



Dear Jibiao Li,


A field of 1 Ry a.u. is giant and atypical, so one should not be surprised do 
not converge.  Recall,  1 in Ry a.u.=36.3609*10^10 V/m.


I also noticed that you impose fixed occupations and then apply Gaussian 
smearing. Those are in contradiction of each other. Apparently the code 
enforces fixed occupations and ignores the smearing.




Mostafa

AUC, New Cairo, Egypt
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