[Pw_forum] error of Gipaw calculation for ethonal

[Emine Kucukbenli]

Dear Xue Yong,

GIPAW calculations require some PAW information to be read from the  
pseudopotentials.
I guess your problem originates from the fact that pseudopotentials  
you use do not have this information.
When the code cannot find this info in the pseudopotential file, it  
looks for other possible files, it cannot find them, and you end up  
having a "read" error.
Even if your problem turns out to be not about GIPAW calculations with  
PAW pseudos, it would be good to clarify this issue once and for all,  
so let me share what I know:

One would expect that if the pseudopotential is indeed made from PAW  
set, like the PS library one you have for C, all info necessary to run  
a GIPAW calculation is obtained during the pseudo generation. It could  
be default to write all this info in the pseudopotential, instead of  
what we do now: writing only the parts useful for pw.x. If we did so,  
every newly generated PAW pseudo could be readily used by gipaw.x too,  
which I thought would be great but met some resistance from the  
developers side I am afraid.

Still, thanks to the recent addition of pseudopotential input file in  
the pseudopotential file itself, you can take any new generation paw  
pseudo and make it suitable for GIPAW calculations yourself.

To demonstrate the procedure I will use the following pseudo as example:
http://www.quantum-espresso.org/wp-content/uploads/upf_files/C.pbe-n-kjpaw_psl.0.1.UPF
1-Go to the address above, that is the pseudopotential file
2-Copy the content between the <PP_INPUTFILE> .... </PP_INPUTFILE>  
into a new file, this will be the pseudopotential generation file,  
lets call it C.pp-gipaw.in
3.Modify C.pp-gipaw.in by adding the following two lines inside i  
write below in the &inputp namelist:
&inputp
..
lgipaw_reconstruction = .true.
use_paw_as_gipaw = .true.
..
/

4.Now, generate the new pseudopotential with gipaw data written in it  
by using the executable ld1.x :
ld1.x < C.pp-gipaw.in
and now,  you have the same pseudo, this time with all PAW info  
written in the pseudo including the core and you can continue your  
gipaw calculations.

If you dont have ld1.x executable in the bin/ directory of your local  
distribution, you need to create it by:
"make ld1"

hope it is a wee bit more clear,
best
emine kucukbenli, postdoc at theos, epfl, switzerland