Hi everyone,
I would like to simulate a random coil (1000 beads long) where all atoms are invisible at first. I would like to gradually turn on and increase their pair-wise interactions piece (50 beads) by piece with following commands:
pair_style soft 10.0
pair_coeff 1 1 0.0 10.0
pair_coeff 2 2 0.0 15.0
pair_coeff 1 2 0.0 20.0
fix 1 all nve
fix 2 all langevin 100.0 100.0 1000.0 48279
group mobile id < 1
group temp id <> 1 50
group frozen id > 50
fix 3 frozen setforce 0.0 0.0 0.0
variable prefactor equal ramp(0,100)
fix 4 temp adapt 1 pair soft a * * v_prefactor
run 20000
After this run I redefine the groups as follows:
group mobile id < 50
group temp id <> 50 100
group frozen id > 100
However I would also like to change the potential of the mobile group to lj/cut/coul/cut. I couldn't find any command to change the potential of a group. I f I try to change the potential of type 1 1 or 1 2 or 2 2. It changes the potential of 3 groups.
Is there a way to change the potential of a group of atoms that I missed from the manual and the mailing list ?
Thanks in advance,
-burak
Hi everyone,
I would like to simulate a random coil (1000 beads long) where all atoms are invisible at first. I would like to gradually turn on and increase their pair-wise interactions piece (50 beads) by piece with following commands:
pair_style soft 10.0
pair_coeff 1 1 0.0 10.0
pair_coeff 2 2 0.0 15.0
pair_coeff 1 2 0.0 20.0
fix 1 all nve
fix 2 all langevin 100.0 100.0 1000.0 48279
group mobile id < 1
group temp id <> 1 50
group frozen id > 50
fix 3 frozen setforce 0.0 0.0 0.0
variable prefactor equal ramp(0,100)
fix 4 temp adapt 1 pair soft a * * v_prefactor
run 20000
After this run I redefine the groups as follows:
group mobile id < 50
group temp id <> 50 100
group frozen id > 100
However I would also like to change the potential of the mobile group to lj/cut/coul/cut. I couldn't find any command to change the potential of a group. I f I try to change the potential of type 1 1 or 1 2 or 2 2. It changes the potential of 3 groups.
Is there a way to change the potential of a group of atoms that I missed from the manual and the mailing list ?
you can have only one pair style in your system at a time, unless you
are using a hybrid pair style.
each subset of atoms that is having a different pair style within a
hybrid pair style would have to have
different atom types. keep in mind that a computer program doesn't
think like a human.
you have to make it easy for the program to follow your instructions.
cheers,
axel.
Two additional comments.
You cannot "redefine" groups in LAMMPS
without using group delete. So your new
group commands are not doing what you think.
You should check carefully that the final set
of atoms in each of your groups are what
you want them to be.
Second, pair styles/coeffs in LAMMPS
are assigned to atom types, not to groups.
The only way to control this is by assigning
types to atoms. This can be changed on the
fly via the "set" command.
Steve