I understand that Qunatum Espresso on its will change centered cell to primitive,not changing the overal symmetry ... It create equivalent descriptipn in lover system with primitive cell automatically ... And it change the crystallographic system and lattice parameters as well ....
The question is whatever it indicate this change somwhere and give the transformation matrix used for transforming the input to the output ... So we can reconstruct from the QE output the standard crystallographic description based on standard space groups witch use centered cells (corresponding to coordinates and centered space group given at the input) ... We can probably decipher what is QE doing internaly, but it will be more easy to have the used transformation in the output file ... Michal ________________________________ From: users <[email protected]> on behalf of Paolo Giannozzi <[email protected]> Sent: Thursday, December 23, 2021 10:25:42 AM To: Quantum ESPRESSO users Forum Subject: Re: [QE-users] QE automatically converge centered cell to primitive ? I am not sure I understand what you mean. If you supply the structure and atomic positions via the space group and Wyckoff positions, QE generates the primitive (smallest) unit cell and corresponding lattice. QE does not change the symmetry or the structure by its own will, unless there is a bug for your specific case. If you prefer the so-called "conventional" unit cell, you need to consider the atoms that are in the conventional unit cell but not in the primitive one. Paolo On Wed, Dec 22, 2021 at 5:07 PM Michal Husak <[email protected]<mailto:[email protected]>> wrote: Hi We had entered inside QE a structure described by fractional coordinates (asymmetric unit cell) and space group (C 2/c ) .... From the output we see QE had itself transformed the structure to another space group and unit cell (probably P 2/c triclinic system) to get speed of calculation .... Question: - does QE anywhere mention, this transformation was done ? - does it anywhere give the used transformation matrix ? We simply need to reconstruct from the QE the atom positions corresponding to the original CIF data .... Michal Husak UCT Prague _______________________________________________ Quantum ESPRESSO is supported by MaX (www.max-centre.eu<http://www.max-centre.eu>) users mailing list [email protected]<mailto:[email protected]> https://lists.quantum-espresso.org/mailman/listinfo/users -- Paolo Giannozzi, Dip. Scienze Matematiche Informatiche e Fisiche, Univ. Udine, via delle Scienze 206, 33100 Udine, Italy Phone +39-0432-558216, fax +39-0432-558222 _______________________________________________ Quantum ESPRESSO is supported by MaX (www.max-centre.eu) users mailing list [email protected] https://lists.quantum-espresso.org/mailman/listinfo/users
