Dear all,

I was trying to do the GW correction calculation for SiO2 using PAW psps, The

following error message

was met with during the 3rd dataset to calculate the screening:

-------------------------------------------------------------------------------------------------

screening.F90:648:ERROR

Cryst%nsym/=Dtset%nsym, check pawinit and symrhoij

-P-0000

-P-0000 leave_new : decision taken to exit ...

----------------------------------------------------------------------------------------------------

after I change the parameter "symmorphi " from 0 to 1, it worked.

but in tutorial_GW1,

http://www.abinit.org/documentation/hel ... n_gw1.html

it's advised to set this input variable as 0,

I am not sure how much difference would come from the change of this variable?

If anyone is familiar with GW, advices and comments will be welcomed.

Thanks,

The following is my input file ,and the PAW psps I used were downloaded from the

ABINIT PAW table website .

______________________________________________________________________

#crystalline SiO2

#Calculation of the GW corrections

#

# option for output

prtden 1

ndtset 4

gwpara 2 # GW parallelisation on bands

nsym 0

# dataset1: usual self-consistent ground-state calculation

nband1 32 #number of (occ. and emp.) bands to be computed

prtden1 1

# dataset2: calculation of KSS file

iscf2 -2

tolwfr2 1.0d-2

getden2 -1

nband2 60 # number of bands to be computed

kssform2 3

nbandkss2 100 # number of bands in KSS files (-1 maximum)

# dataset3: calculation of the screening (epsilon^-1 matrix)

optdriver3 3 # Screening cal.

gwcalctyp3 2 # GW calculation using numerical integration

symchi3 1 # Symmetryze \chi_0, summation over IBZ

getkss3 -1 # Obtain KSS file from previous dataset

nband3 60 # Bands to be used in the screening cal.

ecutwfn3 2.5 #

ecuteps3 2.5 #

nfreqim3 10

nfreqre3 10

freqremax3 2.0

#ppmfrq3 0.5 # Plasmon-pole frequency

fftgw3 11 # FFT for GW

awtr3 1 # Adler-Wiser expression assuming Time-reversal

# dataset4: calculation of the self-energy matrix elements (GW corrections)

optdriver4 4 # Self-energy calculation

gwcalctyp4 2 #

symsigma4 1 #

getkss4 -2 # Obtain KSS file from dataset 1

getscr4 -1 # Obtain SCR file form previous dataset

nband4 60 # Bands to be used in the Self-Energy cal.

ecutwfn4 2.5 #

ecutsigx4 2.5 #

nkptgw4 1 # number of k-points where to cal. GW correction

kptgw4 0.00 0.00 0.00

bdgw4 12 18 # calculate GW corrections for bands from 12~18

#################### COMMON PART ##################################

#Definition of the unit cell

acell 3*5.41 angstrom

rprim 0.5 0.5 0.0

0.0 0.5 0.5

0.5 0.0 0.5

xred 0.0 0.0 0.0

0.25 0.25 0.25

0.75 0.75 0.75

natom 3

ntypat 2

typat 1 2 2

znucl 14 8

# Definition of the k-point grid

kptopt 1

ngkpt 4 4 4

nshiftk 4

shiftk 0.5 0.5 0.5

0.5 0.0 0.0

0.0 0.5 0.0

0.0 0.0 0.5

istwfk *1

iscf 17 # PAW SCF convergence method

#toldfe 1.0d-10

tolvrs 1.0d-8

# energy cutoff [Ha]:

ecut 10

pawecutdg 20.0

#ecutsm 0.5 # ecut smearing useful when relaxation

occopt 4 #cold smearing

tsmear 0.005

# option for the choice of calculations

diemac 12 # a rough guess of the dielectric constant

ixc 7

nstep 200

# Use only symmorphic operations

symmorphi 0

--

State Key Laboratory for Surface Physics and Chemistry

P.O. Box 718-36,Mianyang 621907

Sichuan, P.R. China

Email:shipeng_2000@163.com

## problem with PAW+GW cal. of SiO2 (nonsymmorphic operations)

**Moderators:** gmatteo, bruneval, rigna

### Re: problem with PAW+GW cal. of SiO2 (nonsymmorphic operations)

The GW documentation is not up-to-date.

Now the GW code can treat nonsymmorphic operations both in screening and in sigma.

Nonsymmorphic operations can always be removed by using symmorphi=0 but

one has to be consistent through all the steps of the calculation.

If the KSS file has been generated with symmorphi=0, then also the screening

calculation as well as the sigma part have to be performed with the same value.

Best Regards

Matteo Giantomassi

Now the GW code can treat nonsymmorphic operations both in screening and in sigma.

Nonsymmorphic operations can always be removed by using symmorphi=0 but

one has to be consistent through all the steps of the calculation.

If the KSS file has been generated with symmorphi=0, then also the screening

calculation as well as the sigma part have to be performed with the same value.

Best Regards

Matteo Giantomassi

### Re: problem with PAW+GW cal. of SiO2 (nonsymmorphic operations)

Dear Matteo Giantomassi,

Thanks for your quick reply,

and here's another question: is there a good way to get GW correction for common k-points?

for example: If you want to calculate the band structure along high symmetry lines, such as L-W-gamma, it's difficult to generate the k-mesh which includes the special k-points you are intrested in, during the KSS file generation procedure. If not included, then the following route to calculate screening would complain the kptgw is not one point in the k-mesh generated before.

I think this is a general problem when doing GW correction calculations.

Any comments and advices are welcomed, thanks,

Shipeng

Thanks for your quick reply,

and here's another question: is there a good way to get GW correction for common k-points?

for example: If you want to calculate the band structure along high symmetry lines, such as L-W-gamma, it's difficult to generate the k-mesh which includes the special k-points you are intrested in, during the KSS file generation procedure. If not included, then the following route to calculate screening would complain the kptgw is not one point in the k-mesh generated before.

I think this is a general problem when doing GW correction calculations.

Any comments and advices are welcomed, thanks,

Shipeng