[Pw_forum] ecut

[Matteo Cococcioni]

Hi,

one thing missing in your input file is ecutrho (the energy cutoff for 
the charge density) (read INPUT_PW).
If you use ultrasoft pseudopotential you need to specify this parameter 
besides the ecutwfc.
It is needed to reconstruct the "hard" (augmentation) part of the charge 
density that you won't obtain
from the square of (soft) wavefunction. Typically, for ultrasoft 
pseudopotential, this parameter is
8 to 12 times the cut-off for the wavefunctions but it can even be 
bigger. If you don't specify
its value the code probably assumes you are using norm conserving 
pseudos and puts
ecutrho = 4.0 * ecutwfc which is not big enough.
I hope this will help.

Matteo


ali kazempoor wrote:
> hi
> i run scf input file for MnAs that has NiAs -type
> (hexagonal)and i use ultrasoft pseudopotentials for Mn
> and As from espersso  and optimize k point but my run
> don't converge at 50 ,55 ,.. rydberg for ecut.please
> correct my input file.
>  &CONTROL
>                        title = MnAs ,
>                  calculation = 'scf' ,
>                 restart_mode = 'from_scratch' ,
>                       outdir =
> '/scratch/kazempour/tmp/MnAs/' ,
>                   pseudo_dir =
> '/home/akazem/espresso-3.2/pseudo/' ,
>                       prefix = MnAs ,
>  /
>  &SYSTEM
>                        ibrav = 4,
>                    celldm(1) = 7.0373,
>                    celldm(3) = 1.5318,
>                          nat = 4,
>                         ntyp = 2,
>                      ecutwfc = 20,
>                      occupations = 'smearing' ,
>                      degauss = 0.05 ,
>                     smearing = 'methfessel-paxton' ,
>                        nspin = 2 ,
>    starting_magnetization(1) = 1.0,
>    starting_magnetization(2) = 0.1,
>  /
>  &ELECTRONS
>             electron_maxstep = 100,
>                     conv_thr = .00001 ,
>  /
> ATOMIC_SPECIES
>    Mn  54.93   Mn.pbe-sp-van.UPF 
>    As  74.92   As.pbe-n-van.UPF 
> ATOMIC_POSITIONS crystal 
>    Mn      0.000000000    0.000000000    0.000000000  
>  
>    Mn      0.000000000    0.000000000    0.500000000  
>  
>    As      0.333333333    0.666666666    0.250000000  
>  
>    As      0.666666666    0.333333333    0.750000000  
>  
> K_POINTS automatic 
>   11 11 9   1 1 1 
>
>
>
>
>  
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