Table 1. Calculated state energies, ^a second moments ^b and vertical excitation energies for ethylene.

	N state		V state		T vert (eV)
	E	〈x2〉	E	〈x2〉
TZV(2d,f;p) + RHF	–78.063860	12.06
(2,2) CASSCF	–78.091437	11.71	–77.782646	22.42	8.40
(4,4) CASSCF	–78.117512	11.63	–77.802123	19.96	8.58
(4,4) MRPT2	–78.391455	—	–78.092863	—	8.12
aug-cc-pVTZ BOVB-5 c	–78.111200	11.64	–77.816658	19.14	8.01

^aUnits of hartree.

^bUnits of a₀², x is out-of-plane.

^c Ref. 16.