NLCC error from pw2bgw

Submitted by caramella on Mon, 02/17/2014 - 02:48

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Hi,
I am using pw2bgw (from QE v5.0 pkg) to convert wfn from QE to BGW format.
I am following instructions in the REAME file of the excercise on BN we performed at the bgw school (last Nov.2013).
(6-boron_nitride/1-mf/2.1-epsilon) Using the same inputs and pseudopotentials we used at the school
on a local bluegene cluster i get this error
Error in routine pw2bgw (2): BGW cannot use NLCC.
What should i change ? Should i compile pw2bgw.f90 in the bgw package instead of the QE ones ?
I am running now a test without NLCC but I am surprised because i am changing PP with respect to the exercise performed at school.
Thanks for clarification, best regards

Submitted by gsm on Mon, 02/17/2014 - 09:02

Hi,
You have several options:
1. Use pseudopotentials without NLCC to avoid this error in QE v5.0.
2. Use pw2bgw.f90 from the development version of QE. You won't see this error anymore, instead pw2bgw.f90 prints a warning message "NLCC is absent" or "NLCC is present".
3. You cannot use pw2bgw.f90 from BerkeleyGW package. This version of pw2bgw.f90 is for QE v4.3.2.

On a side note, if your DFT calculation requires NLCC, it usually means that GW calculation requires semicore pseudopotential without NLCC. If you don't care about accuracy and insist on using NLCC instead of semicore pseudopotential, make sure to set NLCC to zero for GW step. You can do this by setting flag vxc_zero_rho_core to .true. in the input file for pw2bgw.f90. If you don't set NLCC to zero for GW step, BerkeleyGW will produce arbitrary results.

Submitted by caramella on Tue, 02/18/2014 - 01:17

Thank you for your kind answer.
3. I tried already to set vxc_zero_rho_core to .true. but i got again a crash of pw2bgw.
2. I see Dev version of QE is unavailable "until further notice" http://www.quantum-espresso.org/download/
Waiting to have an updated version of pw2bgw (why bgw is not distributing it?)
1. I am running now QE v5.0 using PP without NLCC from QE website.
Best regards

Submitted by gsm on Tue, 02/18/2014 - 08:43

Actually, you don't need Dev version. I just checked this on my local installation and it seems that this issue was fixed in QE v5.0.2. I would suggest to use PP without NLCC for now, and upgrade to QE v5.0.2 when QE website is back online.

Submitted by gsm on Tue, 02/18/2014 - 11:53

> Waiting to have an updated version of pw2bgw (why bgw is not distributing it?)

It is in BGW development version, but they're doing some heavy optimizations on it. Thus, it is even less stable than pw2bgw in QE v5.0, and not included in BGW releases. The stable version is the one in QE v5.0.2.