Table 2: Geometries and relative energies of the minima of the two lowest-lying singlet states of CH2. is the equilibrium interatomic distance, and is the equilibrium ∠HCH.

Geometries Relative energies
(kcal mol−1)*
(bohr) (degree)

Ab initio without corea 2.0965 102.10 −100.54
Ab initio with coreb 2.0914 102.38 −100.70
Our PESsc 2.0920 102.45 −100.70
Liu et al.d 2.098 102.0 −100.3
Flores and Gdanitze 2.0917 102.31
Bussery-Honvault et al.f 2.09 102.5 −99.7
DMBEg 2.09 102.4 −99.75
Exp.h 2.099 102.38
Exp.i

Ab initio without corea 2.0316 143.12 −77.71
Ab initio with coreb 2.0300 144.60 −77.96
Our PESsc 2.0300 144.36 −77.97
Liu et al.d 2.032 143.2 −76.8
Flores and Gdanitze 2.0165 143.39
Bussery-Honvault et al.f 2.02 141 −79.9
Exp.h 1.990
Exp.j 2.052 139.30

*Energies are relative to the C( )+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].