New ab Initio Potential Energy Surfaces for the Renner-Teller Coupled 𝟏^𝟏𝐴^′ and 1^𝟏𝐴^′′ States of CH₂

Table 2

Geometries and relative energies of the minima of the two lowest-lying singlet states of CH₂. 𝑅_𝑒 is the equilibrium interatomic distance, and 𝜃_𝑒 is the equilibrium ∠HCH.

		Geometries		Relative energies; (kcal⋅mol^−1)*
		𝑅𝑒 (bohr)	𝜃𝑒 (degree)
𝑎^1𝐴1	Ab initio without core^a	2.0965	102.10	−100.54
	Ab initio with core^b	2.0914	102.38	−100.70
	Our PESs^c	2.0920	102.45	−100.70
	Liu et al.^d	2.098	102.0	−100.3
	Flores and Gdanitz^e	2.0917	102.31
	Bussery-Honvault et al.^f	2.09	102.5	−99.7
	DMBE^g	2.09	102.4	−99.75
	Exp.^h	2.099	102.38
	Exp.^i	2.092±0.004	102.4±0.4
𝑏̃^1𝐵1	Ab initio without core^a	2.0316	143.12	−77.71
	Ab initio with core^b	2.0300	144.60	−77.96
	Our PESs^c	2.0300	144.36	−77.97
	Liu et al.^d	2.032	143.2	−76.8
	Flores and Gdanitz^e	2.0165	143.39
	Bussery-Honvault et al.^f	2.02	141	−79.9
	Exp.^h	1.990	140±15
	Exp.^j	2.052	139.30

*Energies are relative to the C(¹𝐷)+H₂ asymptote.
^aOur ab initio values using icMRCI(6e, 7o)+Q/AVQZ.
^bOur ab initio values using icMRCI(8e, 8o)+Q/optACVQZ.
^cFrom our PESs.
^dAb initio values using icMRCI(6e, 7o)/AVQZ from [34].
^eAb initio values using icMR-ACPF(8e, 7o)/ACVQZ from [55].
^fPES values from [27, 29].
^gPES values from [30].
^hExperimental values from [2].
ⁱExperimental values from [11].
^jExperimental values from [56].