High-quality ab initio quantum chemical methods, including higher-order coupled cluster and full configuration interaction benchmarks, with basis sets ranging from [C/H] [4s3p1d/2s1p] to [9s8p7d5f4g3h2i/7s6p5d4f3g2h] have been employed to obtain the best technically possible value for the standard enthalpy of formation of X̃ 3B1CH2 and ã 1A1CH2. Careful extrapolations of finite basis MP2, CCSD, CCSD(T), and CCSDT energies to the complete basis set full configuration interaction limit plus inclusion of small corrections owing to relativistic effects, core correlation, and the diagonal Born–Oppenheimer correction results in the final extrapolated enthalpies of formation of this study, ΔfH0o(X̃ 3B1CH2)=390.45−0.64+0.68kJmol−1 and ΔfH0o(ã 1A1CH2)=428.10−0.64+0.68kJmol−1. The computed value for X̃ 3B1CH2 is in between the best two experimental results of 389.87±0.86 and 390.73±0.66 kJmol−1. The elaborate calculations leading to these enthalpies of formation also resulted in accurate estimates of the singlet-triplet splitting, T0(ã 1A1CH2)=37.54−0.29+0.41kJmol−1, in excellent agreement with the best empirical value of 37.65±0.06 kJmol−1, of the total atomization enthalpy, D0(X̃ 3B1CH2)=753.03−0.62+0.43kJmol−1, in excellent agreement with the best experimental value of 753.3 kJmol−1, of the bond dissociation energy, DU1o(0 K)(CH–H)=417.85±0.35 kJmol−1, and of the quartic force field representations of the potentials of the two states around their respective minima.

1.
S. W. Benson, Thermochemical Kinetics (Wiley, New York, 1976).
2.
R.
Deters
,
M.
Otting
,
H. G.
Wagner
,
F.
Temps
,
B.
László
,
S.
Dóbé
, and
T.
Bérces
,
Ber. Bunsenges. Phys. Chem.
102
,
58
(
1998
).
3.
R. D. A.
Pereira
,
D. L.
Baulch
,
M. J.
Pilling
,
S. H.
Robertson
, and
G.
Zeng
,
J. Phys. Chem. A
101
,
9681
(
1997
).
4.
J.
Bertran
,
Theor. Chem. Acc.
99
,
143
(
1998
).
5.
I. Glassman, Combustion (Academic, San Diego, 1996).
6.
D.
Rossini
,
J. Chem. Thermodyn.
8
,
805
(
1976
).
7.
D.
Rossini
,
J. Chem. Thermodyn.
28
,
1195
(
1996
).
8.
K. J.
Hughes
,
T.
Turányi
,
A.
Clague
, and
M. J.
Pilling
,
Int. J. Chem. Kinet.
33
,
513
(
2001
).
9.
T.
Turányi
,
L.
Zalotai
,
S.
Dóbé
, and
T.
Bérces
,
Phys. Chem. Chem. Phys.
4
,
2568
(
2002
).
10.
B.
Ruscic
,
D.
Feller
,
D. A.
Dixon
,
K. A.
Peterson
,
L. B.
Harding
,
R. L.
Asher
, and
A. F.
Wagner
,
J. Phys. Chem. A
105
,
1
(
2001
).
11.
S.
Parthiban
and
J. M. L.
Martin
,
J. Chem. Phys.
114
,
6014
(
2001
).
12.
B.
Ruscic
,
A. F.
Wagner
,
L. B.
Harding
et al.,
J. Phys. Chem. A
106
,
2727
(
2002
).
13.
A. G.
Császár
,
P. G.
Szalay
, and
M. L.
Leininger
,
Mol. Phys.
100
,
3879
(
2002
).
14.
W. D. Allen, A. L. L. East, and A. G. Császár, in Structures and Conformations of Nonrigid Molecules, edited by J. Laane, M. Dakkouri, B. van der Veken, and H. Oberhammer (Kluwer, Dordrecht, 1993), NATO ASI Series C: Mathematical and Physical Sciences.
15.
A. G.
Császár
,
W. D.
Allen
, and
H. F.
Schaefer
III
,
J. Chem. Phys.
108
,
9751
(
1998
).
16.
A. G.
Császár
and
M. L.
Leininger
,
J. Chem. Phys.
114
,
5491
(
2001
).
17.
A. G.
Császár
,
M. L.
Leininger
, and
A.
Burcat
,
J. Phys. Chem. A
107
,
2061
(
2003
).
18.
M. W.
Chase
, Jr.
,
C. A.
Davies
,
J. R.
Downey
, Jr.
,
D. J.
Frurip
,
R. A.
MacDonald
, and
A. N.
Syverud
,
J. Phys. Chem. Ref. Data Suppl.
14
,
Suppl
.
1
(
1985
).
19.
M. W.
Chase
, Jr.
,
J. Phys. Chem. Ref. Data Monogr.
14
,
Suppl
.
1
(
1998
).
20.
J. D. Cox, D. D. Wagman, and V. A. Medvedev, CODATA Key Values for Thermodynamics (Hemisphere, New York, 1989).
21.
I. Barin, Thermochemical Data for Pure Substances (VCH, Weinheim, 1993).
22.
J.
Berkowitz
,
G. B.
Ellison
, and
D.
Gutman
,
J. Phys. Chem.
98
,
2744
(
1994
).
23.
Energetics of Organic Free Radicals, Structure, Energetics and Reactivity in Chemistry (SEARCH) Series, edited by J. A. M. Simoes, A. Greenberg, and J. F. Liebman (Chapman and Hall, London, 1996).
24.
W. B. DeMore, S. P. Sander, D. M. Golden, R. F. Hampson, M. J. Kurylo, C. J. Howard, A. R. Ravishankara, C. E. Kolb, and M. J. Molina, Chemical Kinetics and Photochemical Data for Use in Stratospheric Modeling, Evaluation No. 12, JPL Publication 97-4, NASA and JPL (1997).
25.
R.
Atkinson
,
D. L.
Baulch
,
R. A.
Cox
,
R. F.
Hampson
, Jr.
,
J. A.
Kerr
,
M. J.
Rossi
, and
J.
Troe
,
J. Phys. Chem. Ref. Data
29
,
167
(
2000
).
26.
J. A. Kerr, CRC Handbook of Chemistry and Physics, 81st ed. (CRC, Boca Raton, FL, 2000–2001).
27.
Computational chemistry comparison and benchmark database, http://srdata.nist.gov/cccbdb/
28.
A. L. L.
East
and
W. D.
Allen
,
J. Chem. Phys.
99
,
4638
(
1993
).
29.
D. A.
Dixon
,
D.
Feller
, and
G.
Sandrone
,
J. Phys. Chem.
103
,
4744
(
1999
).
30.
C. W.
Bauschlicher
, Jr.
,
J. M. L.
Martin
, and
P. R.
Taylor
,
J. Phys. Chem. A
103
,
7715
(
1999
).
31.
K. K. Irikura and D. J. Frurip, Computational Thermochemistry: Prediction and Estimation of Molecular Thermodynamics (American Chemical Society, Washington, D.C., 1998).
32.
J. M. L.
Martin
and
G.
de Oliveira
,
J. Chem. Phys.
111
,
1843
(
1999
).
33.
T. Helgaker, W. Klopper, A. Halkier, K. L. Bak, P. Jørgensen, and J. Olsen, Quantum Mechanical Prediction of Thermochemical Data (Kluwer Academic, New York, 2001).
34.
K. L.
Bak
,
P.
Jørgensen
,
J.
Olsen
,
T.
Helgaker
, and
W.
Klopper
,
J. Chem. Phys.
112
,
9229
(
2000
).
35.
A.
Langer
,
J. A.
Hipple
, and
D. P.
Stevenson
,
J. Chem. Phys.
22
,
1836
(
1954
).
36.
W. A.
Chupka
,
J.
Berkowitz
, and
D. J.
Meschi
,
Adv. Mass Spectrom.
2
,
99
(
1963
).
37.
Bell
,
Prog. Phys. Org. Chem.
2
,
1
(
1964
).
38.
V. H.
Dibeler
,
M.
Krauss
,
R. M.
Reese
, and
F. N.
Harllee
,
J. Chem. Phys.
42
,
3791
(
1965
).
39.
J. A.
Kerr
,
Chem. Rev. (Washington, D.C.)
66
,
465
(
1966
).
40.
W. A.
Chupka
and
C.
Lifshitz
,
J. Chem. Phys.
48
,
1109
(
1968
).
41.
W. A.
Chupka
,
J. Chem. Phys.
48
,
2337
(
1968
).
42.
J. L.
Franklin
,
J. G.
Dillard
,
H. M.
Rosenstock
,
J. T.
Herron
,
K.
Draxl
, and
F. H.
Field
, Natl. Stand. Ref. Data Ser. (U.S., Natl. Bur. Stand.) 26 (1969).
43.
W. A.
Chupka
,
J.
Berkowitz
, and
K. M. A.
Refaey
,
J. Chem. Phys.
50
,
1938
(
1969
).
44.
K. E.
McCulloh
and
V. H.
Dibeler
,
J. Chem. Phys.
64
,
4445
(
1976
).
45.
R. K.
Lengel
and
R. N.
Zare
,
J. Am. Chem. Soc.
100
,
7495
(
1978
).
46.
D. G.
Leopold
,
K. K.
Murray
,
A. E. S.
Miller
, and
W. C.
Lineberger
,
J. Chem. Phys.
83
,
4849
(
1985
).
47.
C. C.
Hayden
,
D. M.
Neumark
,
K.
Shobatake
,
R. K.
Sparks
, and
Y. T.
Lee
,
J. Chem. Phys.
76
,
3607
(
1982
).
48.
B.
Ruscic
,
M.
Litorja
, and
R. L.
Asher
,
J. Phys. Chem.
103
,
8625
(
1999
).
49.
S.
Willitsch
,
L. L.
Imbach
, and
F.
Merkt
,
J. Chem. Phys.
117
,
1939
(
2002
).
50.
W. M.
Klopper
,
K. L.
Bak
,
P.
Jørgensen
,
J.
Olsen
, and
T.
Helgaker
,
J. Phys. B
32
,
103
(
1999
).
51.
H. Partridge, in The Encyclopedia for Computational Chemistry, edited by P. v. R. Schleyer, N. L. Allinger, T. Clark, J. Gaisteiger, P. A. Kollmann, H. F. Schaefer III, and P. R. Schreiner (Wiley, Chichester, 1998), Vol. 1, pp. 581–591.
52.
A. G.
Császár
and
W. D.
Allen
,
J. Chem. Phys.
104
,
2746
(
1996
).
53.
R. D.
Cowan
and
M.
Griffin
,
J. Opt. Soc. Am.
66
,
1010
(
1976
).
54.
K. Balasubramanian, Relativistic Effects in Chemistry, Part A: Theory and Techniques and Part B: Applications (Wiley, New York, 1997).
55.
G.
Tarczay
,
A. G.
Császár
,
W.
Klopper
, and
H. M.
Quiney
,
Mol. Phys.
99
,
1769
(
2001
).
56.
N. C.
Handy
,
Y.
Yamaguchi
, and
H. F.
Schaefer
III
,
J. Chem. Phys.
84
,
4481
(
1986
).
57.
W.
Kutzelnigg
,
Mol. Phys.
90
,
909
(
1997
).
58.
E. F.
Valeev
and
C. D.
Sherrill
,
J. Chem. Phys.
118
,
3921
(
2003
).
59.
J. A.
Pople
,
M.
Head-Gorson
,
D. J.
Fox
,
K.
Raghavachari
, and
L. A.
Curtiss
,
J. Chem. Phys.
90
,
5622
(
1989
).
60.
L. A.
Curtiss
,
K.
Raghavachari
,
G. W.
Trucks
, and
J. A.
Pople
,
J. Chem. Phys.
94
,
7221
(
1991
).
61.
L. A.
Curtiss
,
K.
Raghavachari
,
P. C.
Redfern
,
V.
Rassolov
, and
J. A.
Pople
,
J. Chem. Phys.
109
,
7764
(
1998
).
62.
L. A.
Curtiss
,
K.
Raghavachari
,
P. C.
Redfern
, and
J. A.
Pople
,
J. Chem. Phys.
112
,
1125
(
2000
).
63.
L. A.
Curtiss
and
K.
Raghavachari
,
ACS Symp. Ser.
677
,
176
(
1998
).
64.
D. J.
Henry
,
M. B.
Sullivan
, and
L.
Radom
,
J. Chem. Phys.
118
,
4849
(
2003
).
65.
J. A.
Montgomery
,
J. W.
Ochterski
, and
G. A.
Petersson
,
J. Chem. Phys.
101
,
5900
(
1994
).
66.
J. A.
Montgomery
,
M. J.
Frisch
,
J. W.
Ochterski
, and
G. A.
Petersson
,
J. Chem. Phys.
110
,
2822
(
1999
).
67.
T. H.
Dunning
, Jr.
,
J. Chem. Phys.
90
,
1007
(
1989
).
68.
R. A.
Kendall
,
T. H.
Dunning
, Jr.
, and
R. J.
Harrison
,
J. Chem. Phys.
96
,
6796
(
1992
).
69.
A. K.
Wilson
,
T.
van Mourik
, and
T. H.
Dunning
, Jr.
,
J. Mol. Struct.: THEOCHEM
388
,
339
(
1997
).
70.
The (aug)-cc-p(C)VXZ basis sets were obtained from the Extensible Computational Chemistry Environment Basis Set Database, Version 1.0, as developed and distributed by the Molecular Science Computing Facility, Environmental and Molecular Sciences Laboratory, which is part of the Pacific Northwest Laboratory, P.O. Box 999, Richland, Washington 99352, USA and funded by the U.S. Department of Energy. The Pacific Northwest Laboratory is a multiprogram laboratory operated by Battelle Memorial Institute for the U.S. Department of Energy under Contract No. DE-AC06-76RLO 1830.
71.
D.
Feller
,
J. Chem. Phys.
96
,
6104
(
1992
).
72.
G. D.
Purvis
and
R. J.
Bartlett
,
J. Chem. Phys.
76
,
1910
(
1982
).
73.
J.
Noga
and
R. J.
Bartlett
,
J. Chem. Phys.
86
,
7041
(
1987
).
74.
J.
Noga
and
R. J.
Bartlett
,
J. Chem. Phys.
89
,
3401
(E) (
1988
).
75.
G.
Scuseria
and
H. F.
Schaefer
III
,
Chem. Phys. Lett.
152
,
382
(
1988
).
76.
K.
Raghavachari
,
G. W.
Trucks
,
J. A.
Pople
, and
M.
Head-Gordon
,
Chem. Phys. Lett.
157
,
479
(
1989
).
77.
R. J.
Bartlett
,
J. D.
Watts
,
S. A.
Kucharski
, and
J.
Noga
,
Chem. Phys. Lett.
165
,
513
(
1990
).
78.
C. D. Sherrill and H. F. Schaefer III, in Advances in Quantum Chemistry, edited by P.-O. Löwdin (Academic, New York, 1999), Vol. 34, p. 143.
79.
H.
Petek
,
D. J.
Nesbitt
,
D. C.
Darwin
,
P. R.
Ogilby
,
C. B.
Moore
, and
D. A.
Ramsay
,
J. Chem. Phys.
91
,
6566
(
1989
).
80.
PSI 2.0, C. L. Janssen, E. T. Seidl, G. E. Scuseria et al. (PSITECH Inc., Watkinsville, Georgia, 1994).
81.
J. F.
Stanton
,
J.
Gauss
,
J. D.
Watts
,
W. J.
Lauderdale
, and
R. J.
Bartlett
,
Int. J. Quantum Chem.
26
,
879
(
1991
).
82.
J. F. Stanton, J. Gauss, J. D. Watts et al., ACES II, The package also contains modified versions of the MOLECULE Gaussian integral program of J. Almlöf and P. R. Taylor, the ABACUS integral derivative program written by T. U. Helgaker, H. J. Aa. Jensen, P. Jørgensen, and P. R. Taylor, and the PROPS property evaluation integral code of P. R. Taylor.
83.
PSI 3.0, T. D. Crawford, C. D. Sherrill, E. F. Valeev et al. (PSITECH Inc., Watkinsville, Georgia, 1999).
84.
W.
Klopper
and
J.
Noga
,
J. Chem. Phys.
103
,
6127
(
1995
).
85.
DIRCCR12-95 is an electronic structure program written by J. Noga and W. Klopper.
86.
See EPAPS Document No. E-JCPSA6-118-303323 for total energies of C(3P),H(2S),CH(2Π,CH23, and CH21.
A direct link to this document may be found in the online article’s HTML reference section. The document may also be reached via the EPAPS homepage (http://www.aip.org/pubservs/epaps.html) or from ftp.aip.org in the directory /epaps/. See the EPAPS homepage for more information.
87.
A. G. Császár, in The Encyclopedia for Computational Chemistry, edited by P. v. R. Schleyer, N. L. Allinger, T. Clark, J. Gaisteiger, P. A. Kollmann, H. F. Schaefer III, and P. R. Schreiner (Wiley, Chichester, 1998), Vol. 1, pp. 13–30.
88.
D. A.
Clabo
, Jr.
,
W. D.
Allen
,
R. B.
Remington
,
Y.
Yamaguchi
, and
H. F.
Schaefer
III
,
Chem. Phys.
123
,
187
(
1988
).
89.
W. D.
Allen
,
Y.
Yamaguchi
,
A. G.
Császár
,
D. A.
Clabo
, Jr.
,
R. B.
Remington
, and
H. F.
Schaefer
III
,
Chem. Phys.
145
,
427
(
1990
).
90.
W. D.
Allen
and
A. G.
Császár
,
J. Chem. Phys.
98
,
2983
(
1993
).
91.
S. Wolfram, Mathematica: A System for Doing Mathematics by Computer (Addison-Wesley, Redwood City, 1991).
92.
W. D. Allen and co-workers, INTDER95 is a general program developed to perform various vibrational analyses and higher-order nonlinear transformations among force field representations.
93.
I. M. Mills, in Molecular Spectroscopy: Modern Research, edited by K. N. Rao and C. W. Metthews (Acedemic, New York, 1972), Vol. I, pp. 115–140.
94.
A. R. W.
McKellar
,
P. R.
Bunker
,
T. J.
Sears
,
K. M.
Evenson
,
R. J.
Saykally
, and
S. R.
Langhoff
,
J. Chem. Phys.
79
,
5251
(
1983
).
95.
A. D.
McLean
,
P. R.
Bunker
,
R. M.
Escribano
, and
P.
Jensen
,
J. Chem. Phys.
87
,
2166
(
1987
).
96.
D. C.
Comeau
,
I.
Shavitt
,
P.
Jensen
, and
P. R.
Bunker
,
J. Chem. Phys.
90
,
6491
(
1989
).
97.
P.
Jensen
and
P. R.
Bunker
,
J. Chem. Phys.
89
,
1327
(
1988
).
98.
J.-P.
Gu
,
G.
Hirsch
,
R. J.
Buenker
,
M.
Brumm
,
G.
Osmann
,
P. R.
Bunker
, and
P.
Jensen
,
J. Mol. Struct.
517–518
,
247
(
2000
).
99.
P. R. Bunker and P. Jensen (private communication). The value of 3701 cm−1 appearing in Ref. 98 for ZPE1 neglects a contribution of 4Ae=80 cm−1 to it, therefore the correct value is 3701−80=3621 cm−1.
100.
P. R. Bunker and P. Jensen, Molecular Symmetry and Spectroscopy, 2nd ed. (NRC Research, Ottawa, 1998).
101.
M. E.
Jacox
,
J. Phys. Chem. Ref. Data Monogr.
3
,
1
(
1994
).
102.
V.
Szalay
,
J. Mol. Spectrosc.
128
,
24
(
1988
).
103.
V.
Szalay
,
J. Chem. Phys.
92
,
3633
(
1990
).
104.
G.
Tarczay
,
A. G.
Császár
,
W.
Klopper
,
V.
Szalay
,
W. D.
Allen
, and
H. F.
Schaefer
III
,
J. Chem. Phys.
110
,
11971
(
1999
).
105.
P.
Saxe
,
H. F.
Schaefer
III
, and
N. C.
Handy
,
J. Phys. Chem.
85
,
745
(
1981
).
106.
H. F.
Schaefer
III
,
Science (Washington, D.C., U.S.)
231
,
1100
(
1986
).
107.
P. R.
Bunker
,
P.
Jensen
,
W. P.
Kraemer
, and
R.
Beardsworth
,
J. Chem. Phys.
85
,
3724
(
1986
).
108.
C. D.
Sherrill
,
T. J.
Van Huis
,
Y.
Yamaguchi
, and
H. F.
Schaefer
III
,
THEOCHEM
400
,
139
(
1997
).
109.
C. D.
Sherrill
,
M. L.
Leininger
,
T. J.
Van Huis
, and
H. F.
Schaefer
III
,
J. Chem. Phys.
108
,
1040
(
1998
).
110.
A. G. Császár, G. Tarczay, M. L. Leininger, O. L. Polyansky, J. Tennyson, and W. D. Allen, in Spectroscopy from Space, NATO ASI Series C: Math-ematical and Physical Sciences, edited by J. Demaison and K. Sarka (Kluwer, Dordrecht, 2001), pp. 317–339.
111.
E. R.
Davidson
,
D.
Feller
, and
P.
Phillips
,
Chem. Phys. Lett.
76
,
416
(
1980
).
112.
E. R.
Davidson
,
Y.
Ishikawa
, and
G. L.
Malli
,
Chem. Phys. Lett.
84
,
226
(
1981
).
113.
K.
Dyall
,
P.
Pyykko
,
A. G.
Császár
,
G.
Tarczay
,
O. L.
Polyansky
, and
J.
Tennyson
,
Phys. Rev. A
63
,
024502
(
2001
).
114.
P.
Barletta
,
A. G.
Császár
,
H. M.
Quiney
, and
J.
Tennyson
,
Chem. Phys. Lett.
15
,
1229
(
2001
).
115.
D. W.
Schwenke
,
J. Phys. Chem. A
105
,
2352
(
2001
).
116.
P. R. Bunker and P. Jensen (private communication). In Ref. 98, Gu et al. used the incorrect sign for the adiabatic correction (−40 cm−1 instead of the correct +40 cm−1), plus the changed ZPE1 estimate means that the value of 3159 cm−1 reported therein is incorrect.
117.
R. S.
Grev
and
H. F.
Schaefer
III
,
J. Chem. Phys.
97
,
8389
(
1992
).
118.
C. E. Moore, Atomic Energy Levels (U.S. National Bureau of Standards Circular 467, Washington, D.C., 1949).
119.
T. J.
Sears
,
P. R.
Bunker
, and
A. R. W.
McKellar
,
J. Chem. Phys.
77
,
5363
(
1982
).
This content is only available via PDF.

Supplementary Material

You do not currently have access to this content.