[Pw_forum] Help me to solve a problem in Charge Density Difference calculation using Quantum Espresso

[Bibhas Manna]

Dear Matthieu,

Since, I have done the geometry relaxation using *vc-relax,* how can I
maintain the same *Cell_Parameters* for all the three cases.

Thanks.
Bibhas


On Sat, Aug 12, 2017 at 8:22 PM, Matthieu Fortin-Deschênes <
matthieu.fortin-deschenes at polymtl.ca> wrote:

> I'm no expert, but I think you need to make the scf calculations with
> the same parameters, especially ecutrho and CELL_PARAMETERS.
>
> Matthieu
>
> Bibhas Manna <mannabibhas at gmail.com> a écrit :
>
> > Dear Sir,
> >
> > Thanking you for your quick reply.
> >
> > I have used the same parameter for three charges. Following are the input
> > pp.x files:
> >
> >
> > *For Substrate + molecules:*&inputpp
> >     prefix  = 'PG_4_HCHO_PBE'
> >     outdir = './tmp/'
> >     filplot = 'PG_4_HCHO_charge'
> >     plot_num= 0
> >  /
> >  &plot
> >     nfile = 1
> >     filepp(1) = 'PG_4_HCHO_charge'
> >     weight(1) = 1.0
> >     iflag = 2
> >     output_format = 3
> >     fileout = 'PG4_HCHO.rho.dat'
> >     e1(1) =1.0, e1(2)=0, e1(3) = 0.0,
> >     e2(1) =0.0, e2(2)=0.0, e2(3) = 1.0,
> >     nx=56, ny=40
> >  /
> >
> > *For Substrate only:*&inputpp
> >     prefix  = 'PG_4_PBE'
> >     outdir = './tmp/'
> >     filplot = 'PG_4_charge'
> >     plot_num= 0
> >  /
> >  &plot
> >     nfile = 1
> >     filepp(1) = 'PG_4_charge'
> >     weight(1) = 1.0
> >     iflag = 2
> >     output_format = 3
> >     fileout = 'PG4.rho.dat'
> >     e1(1) =1.0, e1(2)=0.0, e1(3) = 0.0,
> >     e2(1) =0.0, e2(2)=0.0, e2(3) = 1.0,
> >     nx=56, ny=40,
> >  /
> >
> >
> > *For Gas molecule only:*&inputpp
> >     prefix  = 'HCHO_PBE'
> >     outdir = './tmp/'
> >     filplot = 'HCHO_charge'
> >     plot_num= 0
> >  /
> >  &plot
> >     nfile = 1
> >     filepp(1) = 'HCHO_charge'
> >     weight(1) = 1.0
> >     iflag = 2
> >     output_format = 3
> >     fileout = 'HCHO.rho.dat'
> >     e1(1) =1.0, e1(2)=0.0, e1(3) = 0.0,
> >     e2(1) =0.0, e2(2)=0.0, e2(3) = 1.0,
> >      nx=56, ny=40,
> > /
> >  I am actually getting  error in the reading of the filepp(2) as follows:
> >
> > Reading header from file  PG_4_HCHO_charge
> >
> >    Info: using nr1, nr2, nr3 values from input
> >      Reading data from file  PG_4_HCHO_charge
> >      Reading data from file  PG_4_charge
> >
> >
> > %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
> %%%%%%%%%%%%%%%%%%
> >      Error in routine chdens (1):
> >      incompatible gcutm or dual or ecut
> >
> > %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
> %%%%%%%%%%%%%%%%%%
> >
> >      stopping ...
> >
> > Thanks.
> > Bibhas
> >
> > On Sat, Aug 12, 2017 at 7:59 PM, stefano de gironcoli <degironc at sissa.it
> >
> > wrote:
> >
> >> you need to compute the three charges with the same parameters
> >>
> >> stefano
> >>
> >>
> >> On 12/08/2017 16:20, Bibhas Manna wrote:
> >>
> >> Dear All,
> >>
> >> I am very new to Quantum Espresso. I want to get a charge density
> >> difference plot for a gas molecule adsorbed on the single layer graphene
> >> surface. Presently I am using pp.x to compute the same in QE v.5.1
> >> following an equation:
> >>
> >>     ∆ρ=ρAB – ρA-ρB
> >>
> >> Where, ρAB, ρA and ρB are the charge densities of graphene -molecule
> >> complex, graphene and molecule respectively. I have successfully
> computed
> >> all of these three charge densities using pp.x. Now, I am trying to find
> >> out the charge density difference using pp.x with nfile = 3, while all
> of
> >> these three charge files are available to me as inputs.
> >>
> >> Unfortunately, I got an error in the output log:
> >> *Error in routine chdens (1):
> >>        incompatible gcutm or dual or ecut*
> >>
> >> Since, I have different number of atoms in each of the three files, how
> >> can I make the charge files having same number of atomic coordinates?
> >>
> >> I am sharing my input and output files for your kind considerations.
> >>
> >> Can you help me to solve this problem?
> >>
> >> Thanks with regards,
> >> Bibhas Manna
> >> Research Scholar,
> >> IIT Kharagpur, India
> >>
> >>
> >>
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