Dear lammps users
I want to calculate the potential energies and forces between 2 rigid bodies built of LJ spheres in vacuum and solution. As the rigid particles are of arbitrary shape i.e. the interaction depends on their mutual orientations I want the particles to rotate while I am measuring the forces for fixed com seperations to receive an orientational averaged force. I used fix rigid for this purpose but as I saw in the manual and using xmovie the positions of the atoms in the rigid bodies are not kept fixed as I would claim. Did I something wrong (see inputscript). Is it only possible to calculate the forces using compute group/group without an time integrator and then rotate the bodies by hand i.e. by changing the datafile, or is there a less tedious way? Is there moreover the possibility to set an initial torque not equal to zero to the rigid bodies.
Thank you for your help
Best regards
Sabine
velocity all create 300 12348765
velocity all zero linear
group cube1 id <> 1 2701
group cube2 id <> 2702 5402
fix 1 all rigid group 2 cube1 cube2 force * off off off
fix 2 all wall/reflect xlo EDGE xhi EDGE ylo EDGE yhi EDGE zlo EDGE zhi EDGE
compute 1 cube1 group/group cube2
compute 2 cube1 com
compute 3 cube2 com
neigh_modify exclude group cube1 cube1
neigh_modify exclude group cube2 cube2
thermo 10
thermo_style custom step etotal c_1 c_1[1] c_1[2] c_1[3] c_2[1] c_2[2] c_2[3] c_3[1] c_3[2] c_3[3]
dump 4 all custom 10 dump id type x y z ix iy iz
run 10000