Defines a variable *name* which holds the energy value to be optimized in
using finite differences. By default, this is `ENERGY(1)` as set by the
most recent program. Other variables which can be used are

`ENERGY`(*i*)- holds last energy for state
*i*. `ENERGR`(*i*)- holds last reference energy for state
*i*. `ENERGD`(*i*)- holds last Davidson corrected energy for state
*i*. `ENERGP`(*i*)- holds last Pople corrected energy for state
*i*. `ENERGC`- holds CCSD (QCI, BCCD) energy in CCSD(T) [QCI(T), BCCD(T)] calculations (single state optimization).
`ENERGT(1)`- holds CCSD(T) energy in CCSD(T) calculations (single state)
`ENERGT(2)`- holds CCSD[T] energy in CCSD(T) calculations (single state).
`ENERGT(3)`- holds CCSD-T energy in CCSD(T) calculations (single state).

These variables are set automatically by the CI and/or CCSD programs. It is the user's responsibility to use the correct variable name; an error exit occurs if the specified variable has not been defined by the last program or the user.

Note: The use of the `VARIABLE` option triggers `NUMERICAL`, so optimization
can be very inefficient!

molpro@molpro.net 2018-11-14