It is easier to figure out what the various "cell_dofree" options do from the code than from the documentation: look for routine 'init_dofree" in Modules/cell_base.f90 (iforceh(i,j)=0 means "keep component i of basis vector j fixed")
Paolo On Tue, Jul 25, 2017 at 12:19 PM, BARRETEAU Cyrille < [email protected]> wrote: > Thanks for your reply but I am still not very sure I understand well the > difference between the two options: > 'xy' : only v1_x and v2_y are moved > '2Dxy' : only x and y components are allowed to change > > When the vectors v1 and v2 are not orthogonal (which is my case) the > option 'xy' is not appropriate ? > > Cyrille > > ======================== > *Cyrille Barreteau* > CEA Saclay, IRAMIS, SPEC Bat. 771 > 91191 Gif sur Yvette Cedex, FRANCE > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > +33 1 69 08 38 56 <+33%201%2069%2008%2038%2056> /+33 6 47 53 66 52 > (mobile) > email: [email protected] > Web: http://iramis.cea.fr/Pisp/cyrille.barreteau/ > ======================== > ------------------------------ > *De :* [email protected] [[email protected]] de la part > de Thomas Brumme [[email protected]] > *Envoyé :* mardi 25 juillet 2017 11:32 > *À :* [email protected] > *Objet :* Re: [Pw_forum] vc-relax & cell_dofree > > Dear Cyrille, > > > from the input description: > > 'xy' : only v1_x and v2_y are moved > > '2Dxy' : only x and y components are allowed to change > > Thus, even in the case of cell_dofree='xy' I think the cell will change. > Anyway, the deviation from 120 DEG is quite small (119.43 DEG if I'm not > wrong) - I don't know if this could be do to numerical issues. Maybe try > starting a new relaxation with a hexagonal cell but smaller in-plane > lattice vector of ~99.1% > > > Cheerio > > > Thomas > > On 07/25/17 09:08, BARRETEAU Cyrille wrote: > > Dear QE community > > I have a question related to vc-relax and the option cell_dofree. > I want to relax a 2D metal-organic framework (MOF) with hexagonal lattice > (ibrav=4) > Could you please explain what is the difference between cell-dofree=xy and > cell_dofree=2Dxy? > > I have noticed that when using cell_dofree=2Dxy the final CELL_PARAMETER > is no longer perfectly hexagonal (see below). Should I use cell_dofree=xy > instead and why? > > final: > CELL_PARAMETERS (alat= 25.44640422) > 0.990921488 -0.000187347 0.000000000 > -0.495622997 0.858299558 0.000000000 > 0.000000000 0.000000000 0.742630080 > > Thanks in advance > > Cyrille > > ======================== > *Cyrille Barreteau* > CEA Saclay, IRAMIS, SPEC Bat. 771 > 91191 Gif sur Yvette Cedex, FRANCE > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > +33 1 69 08 38 56 /+33 6 47 53 66 52 (mobile) > email: [email protected] > Web: http://iramis.cea.fr/Pisp/cyrille.barreteau/ > ======================== > ------------------------------ > > > _______________________________________________ > Pw_forum mailing > [email protected]http://pwscf.org/mailman/listinfo/pw_forum > > > -- > Dr. rer. nat. Thomas Brumme > Wilhelm-Ostwald-Institute for Physical and Theoretical Chemistry > Leipzig University > Phillipp-Rosenthal-Strasse 31 > 04103 Leipzig > > Tel: +49 (0)341 97 36456 <+49%20341%209736456> > > email: [email protected] > > > _______________________________________________ > Pw_forum mailing list > [email protected] > http://pwscf.org/mailman/listinfo/pw_forum > -- Paolo Giannozzi, Dip. Scienze Matematiche Informatiche e Fisiche, Univ. Udine, via delle Scienze 208, 33100 Udine, Italy Phone +39-0432-558216, fax +39-0432-558222
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