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
