Non-adiabatic coupling matrix elements can be computed by finite differences
for `MCSCF` or `CI` wavefunctions using the `DDR` program.
For state-averaged `MCSCF` wavefunctions, they can also computed analytically
(cf. section 19.9.2).

Note that present numerical procedure has been much simplified
relative to `Molpro96`. No `GEOM` and `DISPL` input
cards are needed any more, and the three necessary calculations can be
done in any order.

molpro@molpro.net 2019-01-22