create_atoms and region sphere radius ( wrong?)

At the very bottom of the documentation page, it says the default units
for the region command are "lattice", so you created a region "mdRegion"
that is 10x10x10 lattice units (36.150 Angstroems, in your case) on a
side. You then created region "mySphere" with radius 6 lattice units,
or 21.69 Angstroems (= 6 * 3.6150). You can either specify the radius of
the circle in lattice units, or use "units box" at the end of the region
line to specify simulation box units (i.e., Angstroems for "units metal").

By the way, I have found that it is typically more reliable to intersect
the simulation box with a new region, rather than specifying two separate
regions one with side in and the other with side out. Due to round-off
errors, sometimes one region doesn't precisely match the boundary of the
other (especially near the edge of the simulation box with non-default
lattice orientations).

--Karl

Dear Karl,

Thank you very much for your answer, it's clear now.
I have missed that default option "units = lattice".

Kind regards,
Denis.