[QE-users] Error with pw2gw.x

[Shivesh Sivakumar]

Hello users,

I posted this earlier regarding pw2gw.x and wasn't able to find a solution.
I would be glad if someone could suggest what I can potentially do.

I am trying to calculate the momentum matrix elements for my material with
HSE and HSE+U etc, which is not supported in QE. I already calculated the
matrix elements with PBE, but I want to see if the optical selection rules
change when the hybrid functional is turned on.

I set out to do this with the help of BerkeleyGW- They outline a relatively
simple way that takes into account only the wavefunctions in the inner
product (i.e. the dipole matrix element). This 'finite difference' method
is mentioned in the BerkeleyGW manual ( on arxiv, equation 46).

I tried porting my wavefunctions from QE to GW using pw2gw.x but I am
encountering some errors. Please bear with me while I outline the procedure
I used, and the doubts I have.

1) Use pp.x to save the wavefunction in a readable format. Here is my pp.x
input. To start with, I just want to calculate the matrix element between
the band edges at gamma point. The input below generates the wavefunction
at VBM GAMMA.

&INPUTPP
prefix='CrPs4SCF'
outdir='./'
filplot='wfn'
plot_num=0
kpoint=1
kband=92
/


&PLOT
output_format=5
iflag=3
filepp='./plots'
fileout='./exportgcf'
/

This seems to generate the wavefunction just fine. Did not encounter an
issue here.

2) To convert this wavefunction to a format that BGW can read, I used
pw2gw.x. Here's the input:

&input_pw2bgw
   prefix = 'CrPs4SCF'
   outdir = './'
   real_or_complex = 2
   wfng_flag = .true.
   wfng_file = 'realwfnGW'
   wfng_kgrid = .false.
   wfng_nk1 = 4
   wfng_nk2 = 6
   wfng_nk3 = 1
/

This seems to lead to an error :   Error in routine pw2gw (1):     reading
inputpp namelist.

Would someone be able to tell me where I might have gone wrong? I am also
confused as to what input the pw2gw file reads - Is it the wavefunction
directly from my first step i.e. the output 'plots' from my pp.x
calculation? or should I copy paste the whole SCF directory that includes
the .xml file and charge density data?

Best,
Shivesh Sivakumar
University of Washington-Seattle

On Fri, Jul 10, 2020 at 6:37 PM Shivesh Sivakumar <
shiveshsivakumar at gmail.com> wrote:

> Hello all,
>
> I am trying to calculate the momentum matrix elements for my material with
> HSE and HSE+U etc, which is not supported in QE. I already calculated the
> matrix elements with PBE, but I want to see if the optical selection rules
> change when the hybrid functional is turned on.
>
> I set out to do this with the help of BerkeleyGW- They outline a
> relatively simple way that takes into account only the wavefunctions in the
> inner product (i.e. the dipole matrix element). This 'finite difference'
> method is mentioned in the BerkeleyGW manual (
> https://arxiv.org/pdf/1111.4429.pdf, equation 46).
>
> I tried porting my wavefunctions from QE to GW using pw2gw.x but I am
> encountering some errors. Please bear with me while I outline the procedure
> I used, and the doubts I have.
>
> 1) Use pp.x to save the wavefunction in a readable format. Here is my pp.x
> input. To start with, I just want to calculate the matrix element between
> the band edges at gamma point. The input below generates the wavefunction
> at VBM GAMMA.
>
> &INPUTPP
> prefix='CrPs4SCF'
> outdir='./'
> filplot='wfn'
> plot_num=0
> kpoint=1
> kband=92
> /
>
>
> &PLOT
> output_format=5
> iflag=3
> filepp='./plots'
> fileout='./exportgcf'
> /
>
> This seems to generate the wavefunction just fine. Did not encounter an
> issue here.
>
> 2) To convert this wavefunction to a format that BGW can read, I used
> pw2gw.x. Here's the input:
>
> &input_pw2bgw
>    prefix = 'CrPs4SCF'
>    outdir = './'
>    real_or_complex = 2
>    wfng_flag = .true.
>    wfng_file = 'realwfnGW'
>    wfng_kgrid = .false.
>    wfng_nk1 = 4
>    wfng_nk2 = 6
>    wfng_nk3 = 1
> /
>
> This seems to lead to an error :   Error in routine pw2gw (1):     reading
> inputpp namelist.
>
> Would someone be able to tell me where I might have gone wrong? I am also
> confused as to what input the pw2gw file reads - Is it the wavefunction
> directly from my first step i.e. the output 'plots' from my pp.x
> calculation? or should I copy paste the whole SCF directory that includes
> the .xml file and charge density data?
>
> Best,
> Shivesh Sivakumar
> University of Washington-Seattle
>
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