There is a bug in the subroutine elesp of Mopac 5.0 ESP and the ESP
code in Mopac 6.0.  In Mopac 6.0 all of the ESP code is in the esp.rof
file which gets renamed and compiled if the ESP code is desired.  The
bug is that the z cartesian coordinates being written to unit 21 were
in BOHR whereas the x and y coordinate were in agnstroms which is
what the should be.  The bug is fixed in the download versions on
ouchem.chem.oakland.edu(141.210.108.5).  If you have Mopac 5.0 ESP
download just the file elesp.f and if you have Mopac 6 download esp.rof from
either the vax or unix directories.