Exchange FFT size is too big

Deals with issues related to computation of optical spectra in reciprocal space: RPA, TDDFT, local field effects.

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sdwang
Posts: 287
Joined: Fri Apr 09, 2010 12:30 pm

Exchange FFT size is too big

Post by sdwang » Wed Sep 21, 2011 3:00 pm

Dear developers:
In my BSE calculation, sometimes I found in the log file:
[WARNING]Exchange FFT size is too big. RL vectors reduced to ...
I want to kwon if this warning does matter? And the RL reduced to some value according to waht rule?
Thanks!
S. D. Wang
IMU,HOHHOT,CHINA
E-mail: sdwang@imu.edu.cn

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Daniele Varsano
Posts: 3816
Joined: Tue Mar 17, 2009 2:23 pm
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Re: Exchange FFT size is too big

Post by Daniele Varsano » Wed Sep 21, 2011 4:13 pm

Dear Shudong,

it should be because you have set exchange G vector bigger than the
vector used in the oscillator calculation (FFTGvecs), so it is consistently
set to the FFTGvecs value. If it matters or not, it depends on the considered
values, and you should check it.

Daniele
Dr. Daniele Varsano
S3-CNR Institute of Nanoscience and MaX Center, Italy
MaX - Materials design at the Exascale
http://www.nano.cnr.it
http://www.max-centre.eu/

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