[lammps-users] question about lattice command

Dear Steve,

Many thanks.

Do you means that LAMMPS might report some wrong value of “spacing” in the screen?

According to defination “The lattice spacing in X is defined as the difference between the min/max extent of the x coordinates of the 8 corner points of the modified unit cell…”

The spacing along direction [11-2] should be 8.855, but LAMMPS reported it as 5.90327. Is it a report error?

After using create_atom, which values LAMMPS use actually to map the unit cell into the simulation box? the reported value 5.90327 or the real value 8.855?

Thanks again!

Best regards,

Ruifeng

======== At 2010-01-05, 16:19:12 you wrote: ========

The lattice doc page describes in great detail how the spacings
are calculated. If LAMMPS doesn’t give you the value you
want, you can always set it yourself with the “spacing” option
of the lattice command.

Steve

2010/1/4 ruifeng.zhang <Ruifeng.Zhang@…1645…>

Dear Steve,

I am very interested in LAMMPS code.

Now I am learning to use the LAMMPS code, but I have a question related to the command “lattice” as discibed as follows,

I create a lattice nd constructe a simulated box by the following command

make Cu(111) the upper plane

lattice fcc 3.615 orient z 1 1 1 orient x 1 -1 0 orient y 1 1 -2 origin 0 0 0

If we calculate the lattice spacing along the three directions, the values are listed below,

z: 6.261, x:5.112, y:8.855

But, when I run LAMMPS, the output in the screen is as follows,

Created orthogonal box = (0 0 0) to (97.152 185.935 66.186)
1 by 1 by 1 processor grid
Lattice spacing in x,y,z = 5.11238 5.90327 6.26136
Created 48435 atoms

The x, z directions are consistent, but not for y direction [11-2].

Could you please give me some suggestion about it?

Many thanks in advance!

Best regards,
Ruifeng


2010-01-04


This SF.Net email is sponsored by the Verizon Developer Community
Take advantage of Verizon’s best-in-class app development support
A streamlined, 14 day to market process makes app distribution fast and easy
Join now and get one step closer to millions of Verizon customers
http://p.sf.net/sfu/verizon-dev2dev


lammps-users mailing list
[email protected]
https://lists.sourceforge.net/lists/listinfo/lammps-users

= = = = = = = = = = = = = = = = = = = = = =

LAMMPS is doing what its doc page says. But a particular “spacing”
may not be the periodic repeat distance. For non-orthogonal unit
cells, which are also rotated, I don’t know how to do that.

So again, if you know a better spacing for your lattice, then just
set it to that value.

Steve

2010/1/5 ruifeng.zhang <Ruifeng.Zhang@…1645…>