[ase-users] [ase-developers] ASE calculator interface proposal

[Peterson, Andrew]

On Thu, Jan 24, 2013 at 4:47 AM, Jussi Enkovaara
<jussi.enkovaara at aalto.fi>wrote:

>
> Also, I think that the above approach brings up the question whether
> one attaches atoms to a calculator, and asks calculator to determine
> physical quantities for this atomic configuration, or attaches
> calculator to atoms and asks physical quantities from atoms object, i.e.
> which comes first, atoms or calculator? There is already some
> controversy as some quantities are requested from atoms (energy,
> forces), and some from the calculator (wavefunctions, densities).
> Personally, I do not have strong feelings over this matter, asking atoms
> is maybe a little bit more physics oriented (calculator is just black
> box providing numbers), on the other hand asking calculator would unify
> things in the sense that everything is requested from calculator
> (quantities available from MD calculator are of course quite different
> than the ones availabe from DFT calculator).
>

Don't forget the subtlety that atoms.get_forces() and calc.get_forces() do
not give the same thing back in general. The atoms forces are subject to
constraints, while the calc forces are the raw forces.

The current setup enables one to query the atoms object for the atomistic
parts of the simulation (e.g., geometry optimizations, molecular dynamics)
and query the calculator for the electronic structure parts of the
simulation (e.g., densities of states, electron densities, fields, raw
forces etc.). I like this behavior.

Andy

-- 
Andrew Peterson
Assistant Professor
Brown University School of Engineering
Barus & Holley 247
184 Hope Street
Providence, RI 02912
(401) 863-2153
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