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["P. Ganesh" <pganesh@ciw.edu>]

Dear All,

If anyone has any idea how to get around the problem I have described 
below I would greatly appreciate it.

Thanks,
PGanesh

P. Ganesh wrote:
> Dear All,
>
> I am trying to compute polarization vs electric-field.  If I start 
> with the ground state structure and apply a very small electric-field 
> (~0.00001 a.u) and relax the ions and cell shape only (i.e optcell = 
> 3, ionmmov = 2) then the zeroth broyden step converges with a 
> polarisation along [x0z] direction.  But right after the 1st SCF cycle 
> in broyden step 1 I get the electronic, ionic and total polarisation 
> to be exactly zero.  Further, at SCF 7 the polarization agains become 
> non-zero, and very close to the previous non-zero value and the 
> program aborts with the following warning message:
>
> scfcv (electric field calculation) : WARNING -
>   The difference between pel (electronic Berry phase updated
>   at each SCF cycle)
>   and pel_cg (electronic Berryphase computed using the berryphase 
> routine) is
>   pdif_mod =  0.178600608E+01
>
> pel_cg(1) =  0.000000000E+00
> pel_cg(2) =  0.000000000E+00
> pel_cg(3) =  0.000000000E+00
> pel(1) = -0.886982093E+00
> pel(2) =  0.000000000E+00
> pel(3) = -0.999634356E+00
>
> I dont understand why the polarization suddenly goes to zero at SCF 1 
> and how it suddenly came back to be non-zero? I am using v5.4.4.
>
> Thank you very much.
>
> PGanesh