question about create_box and region

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1

Dear all,

I would like to simulate a nanowire, so I need periodic boundary conditions and a region that is INF in x direction for example.

I don’t understand a part of the manual that says that if I want to use INF as xlo and xhi I have to use first the create_box command. But in the create_box command says that I have to define a region first.

Which of both commands I have to use first?

I have tried this and doesn’t work:

lattice fcc ${latparam}
region whole block 0 3 0 3 INF INF
create_box 1 whole
create_atoms 1 region whole

Can anybody explain me the exact difference between region and box?

Thank you,

Gemma

2

The manual says:

If a region is defined before the simulation box has been created (via
create_box or read_data or read_restart commands), then an EDGE or INF
parameter cannot be used.

This is b/c it doesn't know where the edge of the box is at that point.
You can use a region to create_box to define the simulation
box but it can't be an INF region. That makes no sense.

Periodic boundaries are altogether different. The simulation
box is still of finite size even with PBC.

Steve