[Pw_forum] Hubbard forces without Hubbard U

[Dmitry Novoselov]

Dear Prof. Cococcioni,

I use the QE 5.1 and It seems that the Hubbard forces are calculated well.
But I'm a little puzzled by the next situation.
An analytical expression for the Hubbard forces can be written as:

F^{U}_{\alpha i} = - \frac{U}{2} \sum_{Imm'} (\delta_{mm'} -2n^{I}_{m'm})
\frac{\partial n^{I}_{mm'}}{\partial \tau_{\alpha i}}.

Here alpha is a number of displacement atom in i-direction and U is a
Hubbard correction.
But I have not found the procedure of multiplication by the Hubbard U
correction in the subroutines where Hubbard forces are calculated. Below the
appropriate lines of the corresponding subroutines are listed:

SUBROUTINE forces()
  ...
  CALL force_hub(forceh)
  ...
  force(ipol,na) = force(ipol,na) + forcenl(ipol,na) + forceion(ipol,na) +
forcelc(ipol,na) + forcecc(ipol,na) + forcescc(ipol,na) + forceh(ipol,na)
  ...
END SUBROUTINE forces


SUBROUTINE force_hub(forceh)
  ...
  forceh(ipol,alpha) = forceh(ipol,alpha) - v%ns(m2,m1,is,na) *
dns(m1,m2,is,na)
  ...
END SUBROUTINE force_hub

-- 

 *Best regards,*


*Dr. Dmitry Novoselov Institute for Metal Physics,*
*Yekaterinburg, Russia*


2014-08-14 19:43 GMT+06:00 Matteo Cococcioni <matteo at umn.edu>:

>
> Dear Dmitry,
>
> it should be working. what version of the code are you using?
>
> Matteo
>
>
> On Wed, Aug 13, 2014 at 10:47 AM, Dmitry Novoselov <dnovoselov at gmail.com>
> wrote:
>
>> Dear all,
>>
>> It seems that in the part of the code where the Hubbard forces is
>> calculated (forces and force_hub subroutines), the Hubbard U correction
>> does not taken into account. Is it ok?
>>
>> Thank you!
>>
>> --
>>
>>  *Best regards,*
>>
>>
>> *Dr. Dmitry Novoselov Institute for Metal Physics,*
>> *Yekaterinburg, Russia*
>>
>>
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>
>
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-- 

 *Best regards,*


*Dr. Dmitry Novoselov Institute for Metal Physics,*
*Yekaterinburg, Russia*
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