The odata file

Input is keyword driven with sensible defaults in most cases. The last keyword will usually be POINTS, after which the starting geometry is specified, one atom per line, by the atomic symbol (case insensitive) and the corresponding $x$, $y$ and $z$ coordinates. For potentials that are coded within OPTIM there will always be an assumed unit system. OPTIM determines the potential to be used from the atomic symbol of the last atom, and various symbols have evolved for different systems, as described in §5. Free format may be used within each line. Blank lines are ignored, but there must not be any blank lines after the POINTS keyword.