[ase-users] DftbPlus calculator

[Jens Jørgen Mortensen]

On 03/16/2018 11:26 AM, Ben Hourahine via ase-users wrote:
> Just been looking at the ASE bindings to DFTB+ and noticed that the
> internal (total_energy), not the Mermin free energy (mermin_energy), is
> being collected from results.tag.
>
> This would mean that at finite electron temperatures there can be a
> system dependent discrepancy between the forces and the energy that ASE
> uses.

Most of the calculators in ASE work like that.  They return the energy 
extrapolated to zero temperature, which is normally what you want.  You 
can get the free energy if you ask for it with force_consistent=True:

https://wiki.fysik.dtu.dk/ase/ase/atoms.html#ase.Atoms.get_potential_energy

and structure optimizers do that - I think.

> Incidentally, the introduction at
> https://wiki.fysik.dtu.dk/ase/ase/calculators/dftb.html is slightly out
> of date.
>
> The main DFTB+ site is http://www.dftbplus.org/ and its LGPL3 so does
> not require registration now.

Thanks for the update.  Should be fixed now.

Jens Jørgen

>
>
> Regards
>
> Ben
>