[Pw_forum] What is the meaning of dipfield=.true. ?

[shypirate]

Thanks fro your quick reply!

In my understanding, dipole correction is electrostatic interaction between slabs.
After set dipfield=.true. and other settings remain unchanged, self-consistent calculation has trouble to converge.
In each self-consistent calculation step, there are several "c_bands: * eigenvalues not converged" warning messages. And, after several self-consistent steps, usually 3 steps, program stops with error message: "too many eigenvalues not converged".
Could you give me some advice about this error? Where may be the error in my input file? number of k-points ? My input file for pw.x is like this:

&control
calculation = 'relax',
nstep=200,
tprnfor = .TRUE.,
tefield = .TRUE.,
dipfield = .TRUE.,
prefix = 'relax',
pseudo_dir = '/home/ypwang/espresso/pseudo/',
outdir = './out',
/
&system
ibrav = 6, celldm(1) = 7.35, celldm(3) = 8, nat = 20, ntyp = 5,
ecutwfc = 40.0, ecutrho = 480,
occupations = 'smearing', degauss = 0.005, smearing = 'mv',
edir =3,
emaxpos = 0.9,
eopreg = 0.1,
eamp = 0.00
/
&electrons
diagonalization = 'cg'
mixing_mode = 'local-TF'
mixing_beta = 0.3
conv_thr = 1.0d-8
/
&IONS
bfgs_ndim = 7
/
ATOMIC_SPECIES
...

K_POINTS automatic
4 4 2 1 1 1

Thanks in advance!


2009-10-10 



shypirate 



发件人： Paolo Giannozzi 
发送时间： 2009-10-10  21:21:47 
收件人： PWSCF Forum 
抄送： 
主题： Re: [Pw_forum] What is the meaning of dipfield=.true. ? 
 
On Oct 10, 2009, at 14:07 , shypirate wrote:
> But my question is, what is the meaning if I set dipfield=.true. ?
did you read the documentation for variable dipfield?
                 If .TRUE. and tefield=.TRUE. a dipole correction is  
also
                 added to the bare ionic potential - implements the  
recipe
                 of L. Bengtsson, PRB 59, 12301 (1999). See variables  
edir,
                 emaxpos, eopreg for the form of the correction, that  
must
                 be used only in a slab geometry, for surface  
calculations,
                 with the discontinuity in the empty space.
> If I use dipfield=.false., all results are wrong, is not it?
if you use options without knowing what they do, there are good
changes that all your results are wrong
P.
--
Paolo Giannozzi, Dept of Physics, University of Udine
via delle Scienze 208, 33100 Udine, Italy
Phone +39-0432-558216, fax +39-0432-558222
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