Dear Users, I have three queries as mentioned below:
Query-1 I am relaxing (vc-relax and vc-relax with cell_dofree=xyz) the hybrid perovskite structure. In both, the case the vc-relax goes well and prints final relaxed ordinates (End final coordinates ). As in the newest QE version, 6.2.1, the pw.x run a final scf at the vc-relaxed structure. In my case, the final scf starts but it always stuck at the first iteration: iteration # 1 ecut= 50.00 Ry beta= 0.70 Davidson diagonalization with overlap Could you please help me to figure out the issue why it stuck and what should I do so that the final scf ends without any error. Query-2 My structure is hexagonal with the initial cell dimensions; celldm(1)=16.1636080003d0, celldm(3)=1.3049995364d0, or a= 8.56909772473 b= 8.57159817464 c= 11.2622477409 Vol.= 716.067118376, c/a= 1.31428629976; alpha= 90.0 beta= 90.0 gamma= 120.045402959 after vc-relax I am getting the final cell parameters as below: a= 8.71101209853 b= 8.85373809923 c= 11.4881609903 Vol.= 750.696449907, c/a= 1.31880898113' alpha= 86.512834873 beta= 92.9705116854 gamma= 121.889941369 you see here that the a and b are slightly different while in the hexagonal system they should be same. Also the alpha, beta and gamma are also not at 90, 90 and 120 as supposed to remain at this value in the hexagonal system. To overcome this issue, I have done another vc-relax with "cell_dofree=xyz" to keep fix the lattice angles) I am getting the final cell parameters as below: AA a= 8.87533777693 b= 8.52082228214 c= 11.6157398387 Vol.= 753.329940336, c/a= 1.30876594566 ; alpha= 90.0 beta= 90.0 gamma= 120.954649993 Again we see the variation in the cell parameters. However, the variation is small in comparison to pure vc-relax and alpha and beta are now at fix value. Could you please tell me why I am getting this variation in the cell parameters? Quer-3 If possible, please also cover my previous post which is here: https://www.mail-archive.com/users@lists.quantum-espresso.org/msg33935.html with kind regards K.C. Bhamu CSIR-NCL, Pune, India
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