[Pw_forum] force in sawlike potential

[Lorenzo Paulatto]

In data 21 aprile 2009 alle ore 18:09:59, Aihua Zhang <zah7903 at gmail.com>  
ha scritto:

> Dear Paulatto,
>
> I compared the source codes under PW directory between 4.0.4 and 4.0.5. I
> only found a minor relevant change in compute_dip.f90. I don't think this
> change will affect the force.


In fact, I was about to write there isn't any difference between 4.0.4 and  
4.0.5, even though the sawtooth potential method is going through a  
redesign it won't be released very soon.

What may be problematic is that your potential is that, in your case,  
emaxpos+eopreg is greater than 1. It should cause no harm, in theory, but  
I suspect the code may have some problem dealing with this case. What does  
it happen if you shift all your system half a basis vector down along the  
z direction?
e.g. if you put the C atom in (0,0,0) and emaxpos=0.45, eopreg=0.10

regards

--
Lorenzo Paulatto
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