Dear LAMMPS users,
I am trying to simulate a sandwich structure with a external pressure on both sides. I am using “setforce” and “aveforce” but this force results in explosion of the structure. My question is that, what is the best way to add force to solids?
What I am doing is fixing the lower part, and pushing down the upper part using following commands:
fix pressdown1 up setforce NULL NULL 0.0
fix pressdown2 up aveforce NULL NULL -0.5
Best Regards,
Banan
Dear LAMMPS users,
I am trying to simulate a sandwich structure with a external pressure on
both sides. I am using "setforce" and "aveforce" but this force results in
explosion of the structure. My question is that, what is the best way to
add force to solids?
one that results in a physically meaningful simulation. when a simulation
"explodes" that usually means that simulation parameters are not physically
meaningful resulting in a divergence in time integration. it is extremely
difficult to give any more specific advice with only such incomplete and
vague information that you provide.
axel.
Dear Axel,
Thank you for your response,This is my full input file:
units metal
newton on
#----------------------------- User Input Variables --------------------------------------
# temperature
variable T equal 300
#cold region temperature
variable tlo equal 300
#hot region temperature
variable thi equal 400
#time step (picoseconds)
variable dt equal 0.0005 # 0.5 femtoseconds
#number of time steps for NVT
variable tnvt equal 500000
#number of time steps for first NVE
variable t1nve equal 500000
#number of time steps for second NVE
variable t2nve equal 500000
Dear Axel,
Thank you for your response,This is my full input file:
that is useless without the matching data file and there isn't much of an
explanation. please note that just dumping your input on people doesn't
really help much, if it comes without explanations and justification.
there is only one obvious question/advice that you should look into: since
adding the forces seems to trigger your problems, have you validated that
the values you use are meaningful/physical for metal units. ...and if yes,
how?
axel.
…and doesn’t LAMMPS print one or more warnings when you run this input? you should look into those as well.
axel.