C=C Bond Length
	Calibration of the ropt = MP2/aug-cc-pVTZ(G03) model for calculation of approximate equilibrium C=C bond lengths.
	Figure 1.  ropt versus re (or rmrho) bond lengths   PDF
	Linear regression:  ~ re (Å) = 0.98508 × ropt + 0.016137,  RSD = 0.0021 Å.
	Table 1.  C=C Bond Lengths (Å).  ropt = MP2/aug-cc-pVTZ(G03)     Molecule    re   ropt   ~ re |re - ~ re| Ref.     H2C=C=CH2 1.308 1.3090 1.3056 0.002 [1] H2C=C=O 1.31212 1.3171 1.3135 0.0014 [2] H2C=CCl2 1.324 1.3315 1.3278 0.004 c-FHC=CHCl 1.325 1.3294 1.3257 0.001 H2C=CHCl 1.3262 1.3296 1.3259 0.0003 H2C=CC 1.3283 1.3332 1.3288 0.0005 [3] H2C=CH2 1.3297 1.3332 1.3294 0.0003 [4] H2C=CH-CH3 1.3330 1.3351 1.3313 0.0017 [5] H2C=CHCN 1.333 1.3380 1.3342 0.001 H2C=C(CN)2 1.342 1.3431 1.3392 0.003   AVG 0.0015 RMS 0.0018
	[1] Y.Ohshima, S.Yamamoto, M.Nakata, and K.Kuchitsu, J.Phys.Chem. 91,4696(1987).
	[2] R.D.Brown, P.D.Godfrey, D.McNaughton, A.P.Pierlot, and W.H.Taylor, J.Mol.Spectrosc. 140,340(1990).
	[3] C.A.Gottlieb, T.C.Killian, P.Thaddeus, P.Botschwina, J.Flügge, and M.Oswald, J.Chem.Phys. 98,4478(1993).
	[4] R.J.Berry and M.D.Harmony, Struct.Chem. 1,49(1988).
	[5] H.S.Tam, J.-I.Choe, M.D.Harmony, J.Phys.Chem. 95,9267(1991).
	References not given above are given on the following pages:
	H2C=CCl2			c-FHC=CHCl			H2C=CHCl
	H2C=CHCN			H2C=C(CN)2
	Table of Contents
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						Last Modified 18 Oct 2006