[CP2K:3094] Re: guidelines on implementing special kind of collective variable

[Teodoro Laino]

Hi Peter,

I thought a bit on your request and I've foreseen (together with Carlo, a colleagues of mine) quite interesting applications.
Therefore I decided to implement it. 
Check the message on this group on how to use it.

Thanks for the inspiration.
Regards,
Teo

On Feb 9, 2011, at 5:29 PM, Peter wrote:

> Thank you for reply, Teo.
> 
> Looks like it is much more complicated task than I hoped it would be.
> Probably I'll search for some more technically feasible approaches to
> my problem.
> 
> Thanks,
> Peter
> 
> On Feb 9, 4:35 pm, Teodoro Laino <teodor... at gmail.com> wrote:
>> Dear Peter,
>> 
>> it is by far not an immediate task: you need to run 2 SCF calculations for a same geometry (which is not available at the moment).
>> In principle, with some modification you may use a fake mixed_env (2 calculations, using only 1 (the neutral I guess) for propagation).
>> But you still need to implement the possibility of storing/retrieving the energy/forces of the two systems independently.
>> Feasible but not immediate: You need to be extremely well acquainted with the code to implement something like that.
>> 
>> Or alternatively one could implement the possibility to run an additional SCF (without messing up the extrapolation guess) during an MD: in your case you would propagate the neutral system and compute for each geometry an energy/forces for the negative one.
>> 
>> Best,
>> Teo
>> 
>> On Feb 9, 2011, at 2:20 PM, Peter wrote:
>> 
>> 
>> 
>>> Dear CP2K developers!
>> 
>>> I would like to try to implement a special type of collective
>>> variable: it is a difference between potential energy of a system and
>>> potential energy of the system in the same geometry with an extra
>>> electron. In other words, I want to use vertical ionization energy as
>>> a collective variable for e.g. metadynamics.
>>> If there are any caveats regarding this task? E.g. with potential
>>> derivatives calculation.
>>> Could you please give some guidelines on implementing this in cp2k?
>> 
>>> Thanks,
>>> Peter
>> 
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