The ABINIT Users Mailing List ( CLOSED )

["Allan, Douglas C Dr" <AllanDC@corning.com>]

Dear Xavier and Ron,

My reading of Ron's question suggests that he wants a kinetic energy
corresponding with a given charge density that was generated with
wavefunctions at k-points different from the new set.  That is, he does
not have input wavefunctions for the case of interest, he needs to
compute them.  If I am right, then he needs to read the charge density
in and then do a non-self-consistent calculation that is iterated to
convergence in the wavefunctions.  The resulting kinetic energy should
be what he seeks.  I no longer know the proper iscf to achieve this.
Note that he is not going self-consistent again, but he is iterating to
convergence in the wavefunctions.  This should be possible for any
desired k-point grid whether it makes sense as a self-consistent special
points grid or not.  It is the same method one uses to compute a
bandstructure given a charge density.

Best regards,
Doug  

-----Original Message-----
From: Xavier Gonze [mailto:gonze@pcpm.ucl.ac.be] 
Sent: Tuesday, June 12, 2007 9:12 AM
To: forum@abinit.org
Subject: Re: [abinit-forum] non self-consistent kinetic energy

Dear Ron,

On 12 Jun 2007, at 14:36, Ronald Cohen wrote:

> I am trying to figure out how to get ABINIT to compute and print the 
> kinetic energy that corresponds to a  given input  charge density, 
> generated with a different k-point set. This is needed to correct QMC 
> results. It is important to do this  without going self- consistent 
> again.With iscf=-3 I get a total energy, but not the kinetic energy. 
> In fact, if I print results%ek in the code it is zero. Setting nstep 
> to 0 or 1 seems to give nonsense with iscf>0.
>
> Ronald Cohen

Well, I would have said that you have to activate evaluation of the
energy components by the routine energy.F90 (you might have a look at
the header of that routine), which corresponds to nstep=0 . In this
case, the energy is evaluated directly from the input wavefunctions.
Moreover, there is a test case : Test v1#89 (some of the datasets).  
So, I am a bit surprised
to see that nstep 0  gives nonsense for you. Could you send the input
file ?

Best regards,
Xavier