Hello everybody:
The sine vibration in Y direction is applied to an region by fix move wiggle, and then the vibration propagates along X direction. It is found that there is displacement in the X direction during the propagation. Why? Ensemble NVE, amplitude 0.1A, period 2ps! Thanks very much!
Cage
Why not?
Since you apply the wiggle motion only to a part of the system it depends on he specific details of your geometry and your material.
Thank you for your reply. And I’m sorry I didn’t get it. A simple rectangular region and single crystal aluminum are used in the simulation. For more clarity, the code is attached.
In the visualization software, it is found that when the y-direction vibration is applied in the vibration area（source）, the wave will propagate along the x-direction, and the vibration in the x-direction will also be transmitted at this time. What is the way to avoid the displacement in the x-direction ?
##test for Al
##################define variable################
variable a equal 1
variable T equal 0.01
##################Initialization################
units metal
atom_style atomic
boundary m p p
neighbor ${a} bin
neigh_modify delay 0
read_data 1k.data
##################region-group################
region source block INF 50 INF INF INF INF units box
group source region source
region backend block 180 INF INF INF INF INF units box
group backend region backend
region detector block 80 90 INF INF INF INF units box
group detector region detector
group boundary union source backend
group zone subtract all boundary
fix walls all wall/reflect xlo 2 xhi 200 units box
##################potential################
pair_style eam/alloy
pair_coeff * * Al_Zhou04.eam.alloy Al
##################output interatomic information################
thermo 100
thermo_style custom step lx ly lz xy xz yz pxx pyy pzz pxy pxz pyz pe ke temp
##################wave motion process(x)################
velocity source set 0 0 0
fix 1 source setforce 0 0 0
velocity backend set 0 0 0
fix 10 backend setforce 0 0 0
fix 2 source move wiggle 0.0 0.1 0.0 2 units box
fix 3 zone nve
timestep 0.001
dump 1 all custom 100 AL1.lammpstrj id type x y z
timestep 0.001
run 2000
unfix 2
undump 1
dump 2 all custom 100 AL2.lammpstrj id type x y z
timestep 0.001
run 3000
##################output strain and stress################
print “All done”
Sorry, I am not a magician. Just looking at the input doesn’t explain much without actually seeing the exact geometry of the system.
In general, particles interaction not only on one direction, so moving particles can influence particles not just in one direction. That also raises the question about the meaning of suppressing these interactions and thus those motions.
Again, without knowing the exact details of the system it is impossible to say anything more specific.