#
`OLDGEO`

If multiple geometries are to be run, and the final geometry from
one calculation is to be used to start the next calculation, `OLDGEO`
should be specified. Example: If MNDO, AM1, and PM3 calculation, were
to be done on one system, for which only a rough geometry was available,
then after the MNDO calculation, the AM1 calculation could be done using
the optimized MNDO geometry as the starting geometry, by specifying
`OLDGEO`. After the AM1 calculation was done, then a PM3 calculation
could also be done, starting with the old AM1 geometry, by again specifying
`OLDGEO`.
When an `OLDGEO` calculation is started, none of the keywords from the
previous calculation are assumed to be present. Thus, if the first
calculation had keywords `PM3 ROOT=4
CIS C.I.=4`, none of these
keywords would be used by the `OLDGEO` calculation, unless they were
explicitly present in the `OLDGEO` keyword line.