hmmm - yes, that could be a problem.
I'll check when I'm back in the office
next week. What you could certainly do
is create a data file with your coords
in SI units and input the config that way.

Most people use SI units for problems
at the meso or macroscale, not for
problems at the atomic scale.

Does anyone has a sample simulation with SI units and a pair potential?

it is a really, *really* bad idea to do
a simulation an atomic system in SI units.

you are using floating point numbers to do
your math and those have all kinds of practical
problems and limitations and those get larger
the larger in magnitude your exponent is. you
want the exponent to be close to 0.

on top of that, most postprocessing tools
(e.g. for analysis or visualization assume
"real" units, i.e. distances in angstroms)
and can be thoroughly confused if this is
not the case. already using nanometers
instead of angstroms (like gromacs does
it) leads to a lot of confusion and problems.

you are just increasing those massively
without any need.