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

[stefano de gironcoli]

On 12/08/2017 16:52, Matthieu Fortin-Deschênes 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
exactly. stefano

>
> 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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>
>
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