[Pw_forum] PWscf vs. CP

[Nicola Marzari]

Dear Peter,

results should be very close or almost identical.

1) make sure units are right - I'm pretty sure PWscf is Ry/bohr, and
CP should be Ha/bohr (i.e. a factor of 2).

2) make sure you are very well converged. You could even try the
conjugate gradient minimization on CP (but for this you might want to 
download the latest CVS version)

3) there is a bug

				nicola


Peter Winey wrote:
> Dear all,
>  
> I was doing an electronic minimization using the CPV code cp.x. To make 
> sure I did
> not make mistakes, I also did a similar calculation using the PWscf code 
> pw.x.
>  
> Well, when I compared the results, I found quite some difference, 
> in particular, 
> the forces acting on atoms are quite different while the total energy 
> are close.
>  
> My question is whether I should expect to get same results from the two 
> codes?
> If so, there must be something wrong with the input files that I used 
> (see below).
>  
> Thanks in advance for any suggestions that you may have!
> 
> -Peter



---------------------------------------------------------------------
Prof Nicola Marzari   Department of Materials Science and Engineering
13-5066   MIT   77 Massachusetts Avenue   Cambridge MA 02139-4307 USA
tel 617.4522758 fax 2586534 marzari at mit.edu http://quasiamore.mit.edu