Dear lammps users,
I created my tabulated potential for born Mayer potential and ZBL potential , then I used “pair_style hybrid/overlay table linear 10000 ewald coul/long 10” command to combine the long range potential. I got very high temperature and pressure system.
I troubled shoot the problem by once involving the colombic range and once removing it, and I used the “pair_write” command, I found that the potential curve is nearly the same in both cases as if the tabulated potential contains a long range…
I read on the mailing list some of the colleagues were talking about excluding the colombic part from the potential, however my potentials are both for short ranges
Vb=Ae^-r/rho (A,rho are constants)
Vzbl= coloumbic potential* screening function
Can someone help me what am I missing here, is it a problem of cut off distances, should i exclude some terms from the potential or another thing?
Thank you in advance
Regards
Dear lammps users,
I created my tabulated potential for born Mayer potential and ZBL
potential , then I used "pair_style hybrid/overlay table linear 10000
ewald coul/long 10" command to combine the long range potential. I got very
high temperature and pressure system.
I troubled shoot the problem by once involving the colombic range and once
removing it, and I used the "pair_write" command, I found that the
potential curve is nearly the same in both cases as if the tabulated
potential contains a long range..
I read on the mailing list some of the colleagues were talking about
excluding the colombic part from the potential, however my potentials are
both for short ranges
Vb=Ae^-r/rho (A,rho are constants)
Vzbl= coloumbic potential* screening function
Can someone help me what am I missing here, is it a problem of cut off
distances, should i exclude some terms from the potential or another thing?
it is much safer to not include coulomb in the tabulation as there are
many, many ways to make mistakes, but rather add it with hybrid/overlay to
the tabulated potential during the simulation.
axel.
Dear Axel,
Thank you very much for your reply however I didn’t include the Colombic range in my table but when I used the pair write command I found that my table alone(without hybrid overlay with long range potential) evaluates a potential similar to the potential added to colombic range using hybrid overlay command
So do you have any indication what may be the reason for that?
Dear Axel,
Thank you very much for your reply however I didn't include the Colombic
range in my table but when I used the pair write command I found that my
table alone(without hybrid overlay with long range potential) evaluates a
potential similar to the potential added to colombic range using hybrid
overlay command
So do you have any indication what may be the reason for that?
impossible to say from remote. there are so many things that are specific
to your system or specific to your setup or how and what you did.
i've done similar things myself in the past, and they are not easy to get
them work well and correctly.
all you can do is make more tests and debug the entire process step-by-step
and cross-check with the analytical potentials repeatedly until you trust
you are doing it right.
in fact, i would recommend to start with a case, where you do *not* combine
two potentials, but just use one potential and combine two parts of that.
axel.