Dear lammps list
I have a qustion that might be a bit simple so i apologize in advance ,
when i define pair_style lj/cut/coul/long or even pair_style lj/cut/ i also give the cut off distance but then when i define the pair_coeff
i give the cutoff distance for the specific pair type , what i don’t understand is how does lammps treat both of those data ?
does lammps take the cutoff for each type and implements the global cutoff or as soon as you define specific cutoff values for each pair type in the system
the global cutoff doesn’t have any meaning ?
thanks a lot in advance !
Tal
Dear lammps list
I have a qustion that might be a bit simple so i apologize in advance ,
when i define pair_style lj/cut/coul/long or even pair_style lj/cut/ i also
give the cut off distance but then when i define the pair_coeff
i give the cutoff distance for the specific pair type , what
i don't understand is how does lammps treat both of those data ?
does lammps take the cutoff for each type and implements the global cutoff
or as soon as you define specific cutoff values for each pair type in the
system
the global cutoff doesn't have any meaning ?
the latter. however, that only applies to the lj/cut part.
any coul/long cutoff can only be global. the global coulomb
cutoff is not required, it defaults to the lj/cut coulomb.
for confirmation, please re-read the documentation at:
http://lammps.sandia.gov/doc/pair_lj.html
axel.
Hi Axel
First thanks for quick answer , my question regarding the lj/cut/coul/long is due to the fact that i am trying to simulate bulk crystal which have 3 or 4 different types of atoms all of which have charges (but my system is neutral) and also a LJ part of the potential and each of those types have different sigma values so this will only have one global cutoff ?
Thanks!
tal
Hi Axel
First thanks for quick answer , my question regarding the lj/cut/coul/long
is due to the fact that i am trying to simulate bulk crystal which have 3 or
4 different types of atoms all of which have charges (but my system
is neutral) and also a LJ part of the potential and each of those types have
different sigma values so this will only have one global cutoff ?
the global cutoff is only required for the coulomb part.
and that cutoff defaults to, but is effectively independent
from the global lj cutoff. you *can* have per pair of atom
type cutoffs on the lj part of the interactions. what are
the proper choices depends on the exact requirements
of the force field that you are applying to your system.
axel.