[Pw_forum] GADGET and PWSCF

[Lorenzo Paulatto]

In data 30 settembre 2011 alle ore 23:25:38, Alex Shearer  
<alex124678 at nc.rr.com> ha scritto:
> The geometries of adsorption are often non-trivial; in papers dealing
> with similar systems, a tool known as GADGET is often used for geometry
> optimizations (see reference below). It seems that this tool, written in
> python, is designed to work in conjunction with VASP itself.

Dear Alex,
QE includes several optimization methods, one based on the BFGS algorithm  
and a few based on damped dynamics.

On the otehr hand, I could not get a very clear description of what GADGET  
is supposed to do and it is not publicly available. All I could guess for  
mthe paper you cite, is that it runs VASP repeatedly and uses the DIIS  
algorithm to optimize the configuration.

In fact from some reference I could find online it appers that DIIS is  
just a variant of the BFGS method, slightly more efficient in some cases  
but slightly less in others.

My opinion is that just doing a geometry optimization with QE using the  
default setting is probably pretty much the same as doing a VASP+GADGET  
optimization, although I cannot be 100% sure.

best regards



-- 
Lorenzo Paulatto IdR @ IMPMC/UPMC CNRS & Université Paris 6
phone: +33 (0)1 44275 084 / skype: paulatz
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