[Pw_forum] tefield and LSDA II

[Gabriele Sclauzero]

Dear Hanghui Chen,

hanghui chen wrote:
> Dear PWSCF developers,
>        I just want to follow my previous email. After reading the code 
> more carefully, I found in the subroutine input.f90 that if tefield = 
> .true. and nspin > 2, then we have the error message that "LSDA not 
> available with electric field". However, nspin > 2 or more precisely 
> speaking nspin = 4 means non-collinear spin-polarized calculation. nspin 
> = 2 is the standard spin-polarized calculation with magnetization along 
> z direction.

I think you're right, the error message should be rather:

"Noncollinear calculation not available with electric field",

but how could you get that message if you wanted to perform spin-polarized, collinear 
calculations (which corresponds to lsda=.TRUE., internally in the code; why did you write 
lsda=.FALSE. in your previous mail?) ???
It should show up only when you specify noncolin=.TRUE.


>        My question is when tefield = .true., can I do spin-polarized 
> calculation with magnetization along z direction? The error message 
> "LSDA not available with electric field" seems a little bit confusing to me.

If actually it was only a wrong string for the error message (as I think: please someone 
of the developers which know that part of the code confirm) and the code doesn't stop and 
complain when you specify tefield=.TRUE. together with nspin=2, I think you can safely use 
that feature of QE.

Regards

GS


>        Thank you very much.
> 
> 
> Hanghui
> 
> 
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