! EXAM 42.
!  numerical gradient for CN, using open shell CC(2,3).
!
!  This tests the numerical gradient driver, and also
!  emphasizes that the Dunning correlation consistent
!  basis sets should be used in spherical harmonic form.
!
!  A numerical gradient computation requires the energy
!  at the molecule's actual geometry, plus energies at
!  a pair of geometries displaced along each of its
!  totally symmetric directions.
!  A diatomic has 1 totally symmetric degree of freedom,
!  so this run requires 3 energies for 1 gradient.
!
!  See METHOD=FULLNUM in $FORCE for numerical hessians,
!  and RUNTYP=FFIELD for numerical polarizabilities.
!
!  There are 30 AOs, 28 MOs, 2 frozen cores, so 5 alpha
!  and 4 beta valence electrons are correlated.
!
!  E(ROHF)= -92.1960778308, E(CCSD)= -92.4767618032,
!     the CR-CCL energy E(CC(2,3)) = -92.4930167395,
!  and RMS gradient= 0.026601131 at the CC(2,3) level.
!    (will optimize to -92.4941853332 at 1.1966876)
!
 $contrl scftyp=rohf cctyp=cr-ccl mult=2 nzvar=1
         runtyp=gradient numgrd=.true. ispher=1 $end
 $system timlim=4 $end
 $basis  gbasis=ccd $end
 $zmat   izmat(1)=1,1,2 $end
 $ccinp  maxcc=50 $end
 $data
CN...experimental geometry...X-2-sigma-plus state
Cnv 4

C  6.0   0.0 0.0 0.0
N  7.0   0.0 0.0 1.1718
 $end