Hi all,
I would like to run a simulation with bonded and angle interactions. In this simulation, I want to remove angle interactions once a critical angle limit has been reached, similar to bonds in fix bond/break.
In my simulations, I output all the angles and angle types through “compute angle/ local” and “compute property/local” commands. Then I check all the angles in the list whether they meet the threshold, and if any of them do, I change their angle coefficients (harmonic in my case) to 0. Here is the input script and data file for a simple case of 3 atoms :
INPUT SCRIPT
building simulation input
units si
boundary p p p
atom_style angle
bond_style harmonic
angle_style harmonic
read_data debug_angle_data_file.txt
group support id 1 3
group load id 2
pair_style none
atom_modify sort 10 1
neighbor 1.000000 bin
neigh_modify every 10 check yes
timestep 0.000005
fix 1 load addforce 0 0 -100
fix 2 support setforce 0 0 0
fix 3 all nve
compute 1 all angle/local theta eng
compute 2 all property/local atype
compute PotEn_Angle all pe angle
thermo 1000
thermo_style custom step pe ke etotal temp
dump 1 all xyz 1000 movie.xyz
dump 2 all local 1000 THETA.txt c_1[1] c_1[2] c_2
variable ang equal c_1[1]
variable ang_type equal c_2
label loopa
variable a loop 1000
print “A = $a”
run 1000
if “{ang} < 179" then & "angle_coeff {ang_type} 0 0”
next a
jump debug_angle.txt loopa
DATA FILE
%building input file
3 atoms
2 bonds
1 angles
1 atom types
2 bond types
1 angle types
-50 50 xlo xhi
-50 50 ylo yhi
-50 50 zlo zhi
Masses
1 0.001
Bond Coeffs
1 1000000 0.1
2 1000000 0.1
Angle Coeffs
1 0.9 180
Atoms
1 1 1 0 0 0
2 2 1 0.1 0 0
3 3 1 0.2 0 0
Bonds
1 1 1 2
2 2 2 3
Angles
1 1 1 2 3
My problem is that I cannot assign values of a local compute to a variable (eg variable ang equal c_1[1], where compute 1 outputs local data), hence I cannot access the results of angular computes. I would really appreciate any suggestions or workarounds!
Regards,
Konstantinos Keremidis
PhD Candidate
Concrete Sustainability Hub
Department of Civil and Environmental Engineering
Massachusetts Institute of Technology