Thank you Davide for the clarification. On Wed, Dec 16, 2009 at 6:30 PM, Davide Ceresoli <ceresoli at mit.edu> wrote:
> On Wed, 16 Dec 2009, mohamed sabri majdoub wrote: > > > Dear Davide, > > > > If I change celldim(1)=1.8897261 (in Bohr radius unit), this means that > the crystal lattice > > vectors are in Bohr too (same unit as alat). > Yes, the lattice vectors must be bohrradius unit. > > > Crystal lattice vectors: > > v1(1) v1(2) v1(3) ... 1st lattice vector > > > > v2(1) v2(2) v2(3) ... 2nd lattice vector > > v3(1) v3(2) v3(3) ... 3rd lattice vector > > In alat units if celldm(1) was specified or in a.u. otherwise. > > Am I right? If yes then I need to change the following to Bohr units : > > > > CELL_PARAMETERS > > 8.51980 0.00000 0.00000 > > 0.00000 7.37600 0.00000 > > 0.00000 0.00000 22.6120 > You can change them to bohr units and set celldm(1)=1.0, or > you leave them unchanged but set celldm(1)=1.8897261. > > In any case, the product CELL_PARAMETERS*celldm(1) must always > match your wanted lattice spacings in bohr units, not in angstrom. > > This is in contrast with ATOMIC_POSITIONS, where one can choose > to enter them in angstrom/bohr/alat/crystal units. > > HTH. > > Davide > > > _______________________________________________ > Pw_forum mailing list > Pw_forum at pwscf.org > http://www.democritos.it/mailman/listinfo/pw_forum > -------------- next part -------------- An HTML attachment was scrubbed... URL: http://www.democritos.it/pipermail/pw_forum/attachments/20091216/9140c1b9/attachment-0001.htm
