The ABINIT Users Mailing List ( CLOSED )

[Marek Veithen <Marek.Veithen@ulg.ac.be>]

Dear Chun Li,

ABINIT can do structural optimizations at finite electric field.
However, you have to distinguish 2 cases. First, if you relax the
atomic positions keeping constant the lattice parameters, the calculation
is quite straightforward. Second, if you relax both the atomic positions
and the lattice parameters you have to distiguish between two kinds
of electrical boundary conditions: during the structural optimization, you
can keep constant the electric field or the potential drop across the unit
cell as explained in the paper of I. Souza et al, PRL 89, 117602 (2002).
For the moment, the optimization of lattice parameters at finite
electric field is not properly implemented and should be avoided.

Concerning the calculation you did, as a general rule, you must initialize
a finite field calculation from a calculation at zero field and increase
the amplitude of the electric field in small steps. Moreover, the
electric field must be smaller than the critical field. Please find
enclosed a modified version of your input file.

Best regards,
Marek



Chun Li wrote:

> Dear abinit users,
>
> When I tried to optimize the cell with electric field applied using
> ABINIT 4.4.2, I got the following BUG in the end of the log file:
>
> cgwf (electric field): WARNING -
>  New trial energy at line       4 =  -3.274174E-03
>     is higher than former: -3.304785E-03
>
> cgwf (electric field) : BUG -
>  For k-point #   21 and band #  18,
>  the determinant of the overlap matrix is found to be 0.
>  Action : contact ABINIT group.
>
> Delivered   32 WARNINGs and   2 COMMENTs to log file.
>
> leave_new : decision taken to exit ...
>
> I wonder if ABINIT can perform such kind of calculations. If yes, how to
> overcome this BUG then? Thanks you. I am eager to receive your reply.
>
> My input:
>  optcell    2
>   ionmov    2
>    ntime    100
>  dilatmx    1.1
>   ecutsm    0.5
>   prtgeo    1
>   efield    0.0 0.0 0.006
>    nband    18         
>   kptopt    3        
>    ngkpt    6 6 4
> berryopt    4
>
> #Common data
>    shiftk    0.0 0.0 0.5
>   nshiftk    1
>     acell    6.15956186 6.15956186 9.83980322
>    diemac    9.0
>      ecut    35
>      iscf    3
>     natom    4 
>     nstep    500
>    ntypat    2
>    occopt    1
>    angdeg    90 90 120
>      xred    
> 1.6667200028E-12 -1.6666737435E-12  1.4682831241E-03
> 1.6667292546E-12 -1.6666829953E-12  3.8048074342E-01
> 6.6666666667E-01  3.3333333333E-01  5.0146828312E-01
> 6.6666666667E-01  3.3333333333E-01  8.8048074342E-01
>    toldfe    1.0d-12
>     typat    1 2 1 2
>     znucl    30 8
>
> Best regards.
>
> Chun Li
>
>
>
>  


--
Marek VEITHEN
Universite de Liege
Institut de Physique, Bat. B5
Allee du 6 aout, 17
B- 4000 Sart Tilman
BELGIUM
                                                                               
Phone : ++(32) (0)4-366.36.12
Fax   : ++(32) (0)4-366.29.90
E-mail: Marek.Veithen@ulg.ac.be

ndtset 4  jdtset 1 2 3 4

 berryopt1    -1       rfdir1     1 1 1
 berryopt2     4       efield2    0.0 0.0 0.0002     getwfk2  1
 berryopt3     4       efield3    0.0 0.0 0.0004     getwfk3  2

 berryopt4     4       efield4    0.0 0.0 0.0006     getwfk4  3
  optcell4     0
   ionmov4     2
    ntime4     100



  dilatmx    1.1
   ecutsm    0.5
   prtgeo    1
    nband    18         
   kptopt    1        
    ngkpt    6 6 4


#Common data
    shiftk    0.0 0.0 0.5
   nshiftk    1
     acell    6.15956186 6.15956186 9.83980322
    diemac    9.0
      ecut    25
      iscf    5
     natom    4 
     nstep    500
    ntypat    2
    occopt    1
    angdeg    90 90 120
      xred    
1.6667200028E-12 -1.6666737435E-12  1.4682831241E-03
1.6667292546E-12 -1.6666829953E-12  3.8048074342E-01
6.6666666667E-01  3.3333333333E-01  5.0146828312E-01
6.6666666667E-01  3.3333333333E-01  8.8048074342E-01
    toldfe    1.0d-12
     typat    1 2 1 2
     znucl    30 8