[lammps-users] (no subject)

Hi,

Now I have a difficult case,I want to simulate two fcc metals with the 2d,but the system told me that fcc cound not be simulated in the 2d case.
so I do not know what can I do it.

next section is my in.* document.
I want to model this condition:
the hi-fixed was loaded the fx,-fy.the lo-fixed was fixed,but when I run it, the hi-fixed was moving,the hi was stopping.
I hope the hi-fixed and hi groups moving together.and the lo group is free.
please give me some advices.

thanks very much.

Mark.H

3d friction simulation

dimension 3
boundary p s p
units real
atom_style atomic
neighbor 0.3 bin
neigh_modify delay 5

create geometry

lattice fcc 3.5
region cubox block 0 10 0 10 -0.25 0.25
lattice fcc 3.6
region pbbox block 0 10 12 22 -0.25 0.25
region box union 2 cubox pbbox
create_box 4 box
mass 1 1.0
mass 2 1.0
mass 3 1.0
mass 4 1.0

atom regions

region lo-fixed block INF INF INF 2 INF INF
region above-lo block INF INF INF 10 INF INF side out
region hi-fixed block INF INF 14 INF INF INF
region below-hi block INF INF 12 INF INF INF side out
region lo-slab block INF INF INF 10 INF INF
region hi-slab block INF INF 12 INF INF INF
region lo-slab1 intersect 2 lo-fixed above-lo
region hi-slab1 intersect 2 hi-fixed below-hi

create 2 surfaces

create_atoms 1 region lo-slab
create_atoms 3 region lo-slab1
create_atoms 1 region hi-slab
create_atoms 2 region hi-slab1

LJ potentials

pair_style lj/cut 2.0
pair_coeff * * 1.0 1.0 2.0

define groups

group lo region lo-slab
group lo type 3
group hi region hi-slab
group hi type 2
group lo-fixed region lo-fixed
group hi-fixed region hi-fixed
group boundary union lo-fixed hi-fixed
group mobile subtract all boundary
set group lo-fixed type 4
set group hi-fixed type 4

initial velocities

compute new mobile temp/partial 0 1 0
velocity mobile create 0.1 482748 temp new

fixes

fix 1 all nve
fix 2 boundary setforce 0.0 0.0 0.0
fix 4 hi-fixed setforce 5.0 -5.0 0.0
fix 3 mobile temp/rescale 200 0.1 0.1 0.02 1.0
fix_modify 3 temp new

Run

timestep 0.0025
thermo 1000
thermo_modify temp new
dump 1 all atom 500 dump.friction
dump 2 all xyz 100 cu-pb.xyz
run 30000

Well, an fcc lattice is a 3d lattice. See the various
2d lattice options that LAMMPS provides, in the
doc page for the lattice command.

Steve

2008/4/9 MARK. H <[email protected]>: