[Pw_forum] Problem with NEB

[Paolo Giannozzi]

On Apr 16, 2008, at 20:58 , Janos Kiss wrote:
>
> The problem is that the configurations after the linear  
> interpolation between
> reactant end product are often 'unchemical' even if i include some
> intermediate images. The WF convergence for these images can be  
> particularly
> problematic in the very first scf step. If the WF is not converged  
> within the
> given maximum number of steps (set to 250 in my case) for one of  
> the images
> the code stops for that given image complaining that ' convergence NOT
> achieved, stopping'.

which convergence is not achieved? scf convergence, or iterative  
diagonalization
convergence ? in the former case, a simple solution might be to set  
conv_elec
to .true. at the last iteration in PW/electrons.f90 (just after the  
call to mix_rho:
   if (idum == niter) conv_elec = .true. )
and leave the code go on with whatever forces it can calculate.
In the latter case, things are more complicated.

It is not difficult to add yet another option to produce such  
behaviour, but there
are already too many, and I think it is not wise to make it the  
default behavior.

Paolo
---
Paolo Giannozzi, Dept of Physics, University of Udine
via delle Scienze 208, 33100 Udine, Italy
Phone +39-0432-558216, fax +39-0432-558222