Dear QE users, I am working with a hexagonal symmetry crystal and I relaxed all internal coordinates and cell parameters with vc-relax-bfgs algorithm.
I have some concern about my results. So, I would like some advice. My initial cell parameter are: 45.48740530000000000 0.00000000000000000 0.00000000000000000 -22.74370265000000000 39.39324854203890000 0.00000000000000000 0.00000000000000000 0.00000000000000000 10.31035723491920000 with vectores 'a' and 'b', as: a = b = 45.48740530000000000 c = 10.31035723491920000 After optimization I got this value: 44.53851082397360000 0.00000000000000000 0.00000000000000000 -22.26925541198680000 38.57148182127630000 0.00000000000000000 0.00000000000000000 0.00000000000000000 10.12292974744850000 In my calculation all operations symmetry are conserved. However if use the cell parameters as: a = 44,53851082397360000 b = 44,53851082482830000 c = 10,12292974744850000 The 'a' and 'b' parameter aren't exactly the same. I did a test, where I use ibrav = 4 celldm(1)= 44.53851082397360000, celldm(3) = 0.227284872 , The component forces of atoms become high than (>10-3). To keep the component forces of atoms less than >10-3, I have to use ibrav = 0 and specify the matriz of cell parameters. With this process, Can I still consider my cell as hexagonal symmetry? Cheers -- Jos? Gadelha da Silva Filho Aluno de Doutorado do Curso de P?s-Gradua??o em F?sica da Universidade Federal do Cear?. -------------- next part -------------- An HTML attachment was scrubbed... URL: http://pwscf.org/pipermail/pw_forum/attachments/20140816/3c08b7cb/attachment.html
