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

[Matthieu Fortin-Deschênes]

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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