Out of range atoms - cannot compute PPPM error

Hi all,

I saw that this error has been discussed in the mail list many times but I
wonder one specific issue and will appreciate it if you can help me. I tried
some of cases and realized that Out of range atoms - cannot compute PPPM
error is due to assigned pair coefficients generally and also in my specific
problem when I set the pair coefficients between the solid and
liquid(water-copper) it works feasibly. But in this case I know that some
interaction must occur between solid-liquid which I can’t observe when I set
these coefficients as zero but otherwise the program will give that error.
By the way I assume this error is due to bad dynamics or initialization of
the problem rather than a fft or etc issue since I get same error when I run
it on a single processor.

there are several reasons that can lead to this conditions. you have
to keep in mind that this error is a symptom and not the cause. think
of it like having a fever: there can be many reasons for it and just
making the fever go away may not solve the sickness.

So do you agree that the coefficients must be non-zero between solid and
liquid? If so, some of the commonly used potentials for this case in the
literature don’t exist in lammps like spohr, as a result do you have any

this is all to vague to make any comment. what "spohr" thing are you
talking about? also, it is _extremely_ simple to code up new styles
that add new potentials to lammps.

advice to set this type of interaction potential correctly using for example
LJ or any other pair styles that you can tell? Please note that I also tried
different combining rules in addition to Berloth like Kong’s to specify LJ
parameters between copper and water once I defined copper-copper, O-O and
H-H.

relying on mixing rules is generally a bad idea unless you have a
force field that is parameterized for this. but even in those cases
you often have exceptions for specific combinations of materials.

axel.