[QE-users] CASTEP to QE setup parameters conversions

[Husak Michal]

Hi all


I was working a lot with CASTEP last years ...

I want to switch some my projects to  QE + do head to head comparison with CASTEP.

I am confused by some selected corresponding setup parameters conversion

(I had handled the rest including input formats conversion myself):


QE: etot_conv_thr  (a.u.]

CASTEP: geom_energy_tol (eV/atom)

Should I simply  recalculate eV to a.u. and multiply by number of atoms in unit cell ?

Why the definition in QE/CASTEP differs ?


QE: forc_conv_thr  (a.u.)

CASTEP: geom_force_tol (eV/angstrem)

I have no idea how to convert this  parameter ....


QE: non existing criteria

CASTEP: geom_disp_tol (angstrem) , Maximal atom displacement during a cycle ..

Sound like QE does not check this criteria ?


QE: ecutrho (Ry), default 4 * ecutwfc

CASTEP: non existing parameter

Any idea why CASTEP does not use this parameter ?


QE: conv_thr  , units not found/missing in manual, probably (a.u.) ?

CASTEP: elec_energy_tol (eV/atom)

Should I simply  recalculate eV to a.u. and multiply by number of atoms in unit cell ?

Why the definition differs ?


Michal Husak

UCT Prague, Department of Solid State Chemistry