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["Anglade Pierre-Matthieu" <anglade@gmail.com>]

Hi,

Here is a list ot tips that may help even thought I've no experience with calculations using an electric field:

1) Since carbon nanotubes may behave as conductor it is not so
surprising that CG can't converge with 24 bands. You may try to
increase this number.
2) Have you try using some preconditioners before complaining about calculations enable to converge?
3) anyway Pulay mixing (7) usualy behaves better than Anderson mixing (3)
4) If all the previous advices are not sufficient what about doing a
converged calculations without electric field then adding the electric
field step by step in a few next dataset?

Best regards

PMA

On 5/26/06, septhiroth0629@hotmail.com <septhiroth0629@hotmail.com > wrote:

Dear all

I try to calculate carbon nanotube with finite electric field,the (3,3)CNT with
z direction electric field,But I find when the electric field is 0 it will convergence, once add the electric field it can't convergence.i also try to add electric field in x direction,but it seem no problem in convergence . Can some help me solve this problem.Thank a lot.

I have try iscf 5 but it have error :
Potential-based CG line minimization not converged after 13 restarts.
Action : read the eventual warnings about lack of convergence

And i also try add nline 15 and nnsclo 10 it still can't convergence
ps:The delta of Etot always around 1.0d-4 but i think it is not enough small.

this is my input file
--
#Definition de la maille elementaire
#**********************************
   acell 30 30 4.656817738
   chkrprim 0

#Definition des atomes
#*********************
   natom 12
   ntypat 1
   znucl 6
   typat 12*1
   ixc 3
   xcart     18.90151127    15             0
             17.97740125    17.52128186    0
             16.95075469    18.37880739    2.328408869
             14.30520634    18.83914653    2.328408869
             13.04924531    18.37880739    0
             11.32780509    16.31786467    0
             11.09848873    15             2.328408869
             12.02259875    12.47871814    2.328408869
             13.04924531    11.62119261    0
             15.69479366    11.16085347    0
             16.95075469    11.62119261    2.328408869
             18.67219491    13.68213533    2.328408869

#Definition de la procedure scf
#******************************
   iscf 3
   nstep 500
   nband 24
   nbdbuf 0


#Definition de la base d'ondes planes
#************************************
   ecut  11
   ecutsm 0.5
   dilatmx 1.05
   kptopt 1
   ngkpt 4 4 4
   nshiftk 1
   shiftk 0.5 0.5 0.5
   toldfe 1.0d-10

ndtset  5
jdtset  11
        21  22  23  24  25     # The additional 8 values of the field have been suppressed to spare CPU time
        #31  32  33  34  35

berryopt11 -1       rfdir11    1 1 1

berryopt21  4       efield21   0.0000  0.0000  0.0001    getwfk21  11
berryopt22  4       efield22   0.0000  0.0000  0.0002    getwfk22  21
berryopt23  4       efield23   0.0000  0.0000  0.0003    getwfk23  22
berryopt24  4       efield24   0.0000  0.0000  0.0004    getwfk24  23
berryopt25  4       efield25   0.0000  0.0000  0.0005    getwfk25  24

--

-- 
Pierre-Matthieu Anglade