Lattice Regarding

Hi Steve,

I am trying to create a lattice structure which has following geometry:

Primitive vectors
a(1) =   5.09000000   .00000000   .00000000
a(2) =    .00000000  6.74800000   .00000000
a(3) =    .00000000   .00000000  4.52300000

Basis Vectors:
Atom    Lattice Coordinates                Cartesian Coordinates

C    .89000000   .25000000   .45000000     4.53010000  1.68700000  2.03535000
C   -.89000000   .75000000  -.45000000    -4.53010000  5.06100000 -2.03535000

C   -.39000000   .75000000   .95000000    -1.98510000  5.06100000  4.29685000
C    .39000000   .25000000   .05000000     1.98510000  1.68700000   .22615000
Fe   .03600000   .25000000   .85200000      .18324000  1.68700000  3.85359600

Fe  -.03600000   .75000000  -.85200000     -.18324000  5.06100000 -3.85359600
Fe   .46400000   .75000000   .35200000     2.36176000  5.06100000  1.59209600
Fe   .53600000   .25000000  -.35200000     2.72824000  1.68700000 -1.59209600

Fe   .18600000   .06300000   .32800000      .94674000   .42512400  1.48354400
Fe  -.18600000  -.06300000  -.32800000     -.94674000  -.42512400 -1.48354400
Fe   .68600000   .43700000   .17200000     3.49174000  2.94887600   .77795600

Fe  -.68600000  -.43700000  -.17200000    -3.49174000 -2.94887600  -.77795600
Fe  -.18600000   .56300000  -.32800000     -.94674000  3.79912400 -1.48354400
Fe   .18600000  -.56300000   .32800000      .94674000 -3.79912400  1.48354400

Fe   .31400000  -.06300000   .82800000     1.59826000  -.42512400  3.74504400
Fe  -.31400000   .06300000  -.82800000    -1.59826000   .42512400 -3.74504400

However, while i write the following in LAMMPS, it shows errors to read the negative basis vectors:

lattice custom 2.55 a1 5.09 0 0 a2 0 6.748 0 a3 0 0 4.523 origin 0.0 0.0 0.0 basis 0.89 0.25 0.45 basis **-**0.89 0.75 0.45 basis -.39 .75 .95 basis .39 .25 .05 basis 0.036 0.25 .852 basis **-**0.036 0.75 .852 basis 0.464 0.75 .352 basis 0.536 0.25 .352 basis 0.186 0.063 .328 basis **-**0.186 0.063 .328 basis 0.686 0.437 .172 basis **-**0.686 0.437 .172 basis 0.186 0.563 .328 basis 0.186 0.563 .328 basis 0.314 0.063 .828 basis **-**0.314 0.063 .828

create_atoms 2 region workpiece basis 1 1 basis 2 1 basis 3 1 basis 4 1 basis 5 2 basis 6 2 basis 7 2 basis 8 2 basis 9 2 basis 10 2 basis 11 2 basis 12 2 basis 13 2 basis 14 2 basis 15 2 basis 16 2

The basis values all have to be from 0-1 to place
atoms inside your unit cell. I imagine you can convert
your negative values to positive ones that place
the atom in the same position in the overall lattice.

Steve

Hi Steve,

Writing this even is showing errors:

lattice custom 1 a1 3.878 0 0 a2 0 3.878 0 a3 0 0 3.878 origin 0.0 0.0 0.0 basis 0 0 0 basis 1 0 1 basis 0 0 1 basis 1 0 0 basis 0 1 0 basis 1 1 0 basis 1 1 1 basis 0 1 1 basis 0.5 0.5 0 basis 0 0.5 0.5 basis 1 0.5 0.5 basis 0.5 0.5 1 basis 0.5 1 0.5 basis 0.5 0.5 1 basis 0.5 0.5 0.5

Regards,
Saurav

The lattice doc page states:

Via the {basis}
keyword you add atoms, one at a time, to the unit cell. Its arguments
are fractional coordinates (0.0 <= x,y,z < 1.0), so that a value of
0.5 means a position half-way across the unit cell in that dimension.

Change your 1s to 0s. It means the same thing.
In fact having 2 entries for (0,0,0) and (0,0,1) would put
two atoms on top of each other. So your input doesn't make sense.

Steve