[Sax-project-users] GW calculation on organic semiconductor --1st

[xiaoyinxie]

Dear Sax developers:
   I am now doing GW calculation with Sax-1.0.0 , When I test the code with examples (example3)by calculating the band gap of Silicon ,It was running well, I got a reasonable bandgap of 0.98eV with 8*8*8 k-mesh .
   Problem came out during I calculting the bandgap of P3HT <poly(3-hexylthiophene)> which has 1-D long polymer chain structure.As I increase the number of k-points ,The band gap decreases relatively .  A  0.26eV band gap of which experimental value is 1.9eV  was obtained with 12*1*1 k-mesh. 
  Similar  problem happens when calculating the band gap of polyacetylene.  
  I am not sure if I wrongly selected the parameters of GW calcultion or SAX code does not fit calculating band gap of oranic semiconductor(or some bugs exist) . 
  Hope you can give me some recommendation.
  My input files are in the next Email titled <GW calculation on organic semiconductor --2st>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://qe-forge.org/pipermail/sax-project-users/attachments/20090420/29130a12/attachment.html