quadratic cut off in lj potential

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1

Dear Lammps-users,

I am trying to introduce quadratic cutoff to LJ potentials to make potential and force to smoothly go to zero at cutoff . There is an option of tail correction by doing

pair_modify tail yes

but here we don’t know the potential format explicitly.

Is there any way to introduce quadratic cutoff in the potential ?

In my case, V® =V(LJ) + c1 +c2r^2

Thanks,
Atreyee

2

Dear Lammps-users,

I am trying to introduce quadratic cutoff to LJ potentials to make potential
and force to smoothly go to zero at cutoff . There is an option of tail
correction by doing

pair_modify tail yes

that is something else. the forces are still cut off with a discontinuity.

but here we don't know the potential format explicitly.

Is there any way to introduce quadratic cutoff in the potential ?

LAMMPS has many variants of lennard-jones. just have a look and check it out.

In my case, V(r) =V(LJ) + c1 +c2r^2

sounds like you want to use lj/smooth (too obvious a name??)

axel.

3

There are a whole slew of choices here. Take a look at lj/smooth,
lj/cut/smooth, lj/gromacs, and lj/cubic.

4

and also

lj/charmm/coul/charmm
lj/charmm/coul/long
http://lammps.sandia.gov/doc/pair_charmm.html

cheers

Andrew