The ABINIT Users Mailing List ( CLOSED )

[Rob <spamrefuse@yahoo.com>]

matthieu verstraete wrote:
>
> In your specific case, it looks like you generate the same grid with
> your 4 shifts as with the default, which is 1 shift of 1/2 1/2 1/2.
> This is somewhat of a coincidence, and with a less cubic system will
> not happen. Try with nshift 1 shiftk 0 0 0 and you will see a
> difference in the energy.

Well, it's not "my specific case", but it's the Tutorial 3.1 example from 
ABINIT !
This example is designed to show the use of nshift and shiftk.

Then obviously this Tutorial 3.1 example is not a good example as it does
not demonstrate the necessity for the use of nshift and shiftk.

With nshift 1 shiftk 0 0 0, the total energy in Tutorial 3.1 goes up a bit.

Rob.

Here is the current input file t31.in of Tutorial 3.1:
acell 3*10.18  
rprim  0.0  0.5  0.5
       0.5  0.0  0.5
       0.5  0.5  0.0
ntypat 1          
znucl 14
natom 2           
typat 1 1         
xred                  
   0.0  0.0  0.0  
   1/4  1/4  1/4  
ecut  8.0         
kptopt 1            
ngkpt 2 2 2
nshiftk 4           
shiftk 0.5 0.5 0.5
       0.5 0.0 0.0
       0.0 0.5 0.0
       0.0 0.0 0.5
nstep 10     
toldfe 1.0d-6          
diemac 12.0