The heats of formation of NH3,NH2, NH and the ionization energies of NH3,NH2, NH, and N have been calculated at high levels of ab initio molecular orbital theory at 0 K. Geometries and frequencies were calculated with coupled cluster theory, including a perturbative treatment of the connected triple excitations and with correlation consistent basis sets up through augmented sextuple zeta in quality. Subsequent extrapolation of the total energies to the complete one-particle basis set limit was performed to further reduce the basis set truncation error. Additional improvements in the atomization energy were achieved by applying corrections for core/valence correlation, scalar relativistic, spin–orbit, and higher order correlation effects. Zero point energies were taken from anharmonic force fields where available or are based on appropriately scaled values. Using the R/UCCSD(T) method, we find the following heats of formation (kcal/mol) at 0 K: ΔHf(NH3)=−9.10±0.17 (calc.) versus −9.30±0.10 (expt.);ΔHf(NH2)=45.27±0.12 (calc.) versus 45.17±0.09 (expt.);ΔHf(NH)=85.92±0.08 (calc.) versus 90.0±4 (expt.);ΔHf(NH3+)=225.44±0.23 (calc.) versus 225.59±0.08 (expt.);ΔHf(NH2+)=303.00±0.20 (calc.) versus 302.60±0.08 (expt.); and ΔHf(NH+)=396.56±0.12 (calc.).

1.
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
).
2.
Y.
Song
,
X-M.
Qian
,
K-C.
Lau
,
C. Y.
Ng
,
J.
Liu
, and
W.
Chen
,
J. Chem. Phys.
115
,
2582
(
2001
), following paper.
3.
D. A.
Dixon
,
D.
Feller
, and
K. A.
Peterson
,
J. Phys. Chem. A
101
,
9405
(
1997
);
D.
Feller
,
D. A.
Dixon
, and
K. A.
Peterson
,
J. Phys. Chem. A
102
,
7053
(
1998
);
D. A.
Dixon
and
D.
Feller
,
J. Phys. Chem. A
102
,
8209
(
1998
);
D.
Feller
and
K. A.
Peterson
,
J. Chem. Phys.
110
,
8384
(
1999
);
D. A.
Dixon
,
D.
Feller
, and
G.
Sandrone
,
J. Phys. Chem. A
103
,
4744
(
1999
);
D.
Feller
and
D. A.
Dixon
,
J. Phys. Chem. A
103
,
6413
(
1999
);
D.
Feller
and
K. A.
Peterson
,
J. Chem. Phys.
108
,
154
(
1998
);
D.
Feller
and
D. A.
Dixon
,
J. Phys. Chem. A
104
,
3048
(
2000
);
D.
Feller
,
J. Comput. Chem.
17
,
1571
(
1996
); the database is available at URL: http://www.emsl.pnl.gov:2080/proj/crdb/
4.
G. D.
Purvis
 III
and
R. J.
Bartlett
,
J. Chem. Phys.
76
,
1910
(
1982
);
K.
Raghavachari
,
G. W.
Trucks
,
J. A.
Pople
, and
M.
Head-Gordon
,
Chem. Phys. Lett.
157
,
479
(
1989
);
J. D.
Watts
,
J.
Gauss
, and
R. J.
Bartlett
,
J. Chem. Phys.
98
,
8718
(
1993
).
5.
T. H.
Dunning
,Jr.
,
J. Chem. Phys.
90
,
1007
(
1989
);
R. A.
Kendall
,
T. H.
Dunning
,Jr.
, and
R. J.
Harrison
,
J. Chem. Phys.
96
,
6796
(
1992
);
D. E.
Woon
and
T. H.
Dunning
, Jr.
,
J. Chem. Phys.
103
,
4572
(
1995
).
6.
The calculations were done with MOLPRO-2000 (H.-J. Werner, P. J. Knowles, J. Almlof et al., MOLPRO, Universität Stüttgart, Stüttgart, Germany, University of Sussex, Falmer, Brighton, England, 1997). All of the work was performed on an SGI Origin 2000 or an SGI PowerChallenge.
7.
C.
Hampel
,
K. A.
Peterson
, and
H.-J.
Werner
,
Chem. Phys. Lett.
190
,
1
(
1990
);
M. J. O.
Deegan
and
P. J.
Knowles
,
Chem. Phys. Lett.
227
,
321
(
1994
);
P. J.
Knowles
,
C.
Hampel
, and
H. J.
Werner
,
J. Chem. Phys.
99
,
5219
(
1988
).
8.
M.
Rittby
and
R. J.
Bartlett
,
J. Phys. Chem.
92
,
3033
(
1988
);
R/UCCSD(T) is requested in MOLPRO by the keyword “UCCSD(T)” when combined with an ROHF wave function.
9.
K. A.
Peterson
,
D. E.
Woon
, and
T. H.
Dunning
, Jr.
,
J. Chem. Phys.
100
,
7410
(
1994
).
10.
Methods in Computational Physics, edited by C. Schwartz (Academic, New York, 1963), Vol. 2;
J. M. L.
Martin
,
Chem. Phys. Lett.
259
,
669
(
1996
).
11.
T.
Helgaker
,
W.
Klopper
,
H.
Koch
, and
J.
Nagel
,
J. Chem. Phys.
106
,
9639
(
1997
);
A.
Halkier
,
T.
Helgaker
,
P.
Jørgensen
,
W.
Klopper
,
H.
Koch
,
J.
Olsen
, and
A. K.
Wilson
,
Chem. Phys. Lett.
286
,
243
(
1998
).
12.
K. P. Huber and G. Herzberg, Molecular Spectra and Molecular Structure: Constants of Diatomic Molecules (Van Nostrand Reinhold, New York, 1979), Vol. 4.
13.
M. E.
Jacox
,
J. Phys. Chem. Ref. Data Monogr.
No. 3 (
1994
).
14.
J. M. L.
Martin
,
T. J.
Lee
, and
P. R.
Taylor
,
J. Chem. Phys.
97
,
8361
(
1992
);
J. M. L.
Martin
and
T. J.
Lee
,
Chem. Phys. Lett.
258
,
129
(
1996
).
15.
W.
Gabriel
,
G.
Chambaud
,
P.
Rosmus
,
S.
Carter
, and
N. C.
Handy
,
Mol. Phys.
81
,
1445
(
1994
).
16.
J. M. L.
Martin
,
J. P.
Francois
, and
R.
Gijbels
,
J. Chem. Phys.
97
,
3530
(
1992
).
17.
M.
Okumura
,
B. D.
Rehfuss
,
B. M.
Dinelll
,
M. G.
Bawendi
, and
T.
Oka
,
J. Chem. Phys.
90
,
5918
(
1989
).
18.
S. J.
Dunlavey
,
J. M.
Dyke
,
N.
Jonathan
, and
A.
Morris
,
Mol. Phys.
39
,
1121
(
1980
).
19.
(a)
J. W.
Rabalais
,
L.
Karlsson
,
L. O.
Werme
,
T.
Bergmark
, and
K.
Seigbahn
,
J. Chem. Phys.
58
,
3370
(
1973
);
(b)
S. S.
Lee
and
T.
Oka
,
J. Chem. Phys.
94
,
1698
(
1991
);
(c)
W.
Habenicht
,
G.
Reiser
, and
K.
Muller-Dethlefs
,
J. Chem. Phys.
95
,
4809
(
1991
);
(d)
G.
Reiser
,
W.
Habenicht
, and
K.
Muller-Dethlefs
,
J. Chem. Phys.
98
,
8462
(
1993
).
20.
K. A. Peterson and T. H. Dunning, Jr. (unpublished).
21.
A.
Berning
,
M.
Schweizer
,
H.-J.
Werner
,
P. J.
Knowles
, and
P.
Palmieri
,
Mol. Phys.
98
,
1823
(
2000
).
22.
E. R.
Davidson
,
Y.
Ishikawa
, and
G. L.
Malli
,
Chem. Phys. Lett.
84
,
226
(
1981
).
23.
P. J.
Knowles
,
Chem. Phys. Lett.
155
,
513
(
1989
).
24.
M. W.
Chase
,Jr.
, NIST-JANAF Tables, 4th ed.,
J. Phys. Chem. Ref. Data Monogr.
, Supp. 1 (
1998
);
NIST WebBook: http://webbook.nist.gov/
25.
K. A.
Peterson
,
S. S.
Xantheas
,
D. A.
Dixon
, and
T. H.
Dunning
,Jr.
,
J. Phys. Chem. A
102
,
2449
(
1998
);
J. M. L.
Martin
and
T. J.
Lee
,
Chem. Phys. Lett.
258
,
129
(
1996
);
J. M. L.
Martin
and
T. J.
Lee
,
Chem. Phys. Lett.
258
,
136
(
1996
);
J.
Del Bene
,
J. Phys. Chem.
97
,
107
(
1993
);
D. J.
DeFrees
and
A. D.
McLean
,
J. Comput. Chem.
7
,
321
(
1986
);
J. A.
Pople
,
M.
Head-Gordon
,
D. J.
Fox
,
K.
Raghavachari
, and
L. A.
Curtiss
,
J. Chem. Phys.
90
,
5622
(
1989
);
L. A.
Curtiss
,
K.
Raghavachari
,
G. W.
Trucks
, and
J. A.
Pople
,
J. Chem. Phys.
94
,
7221
(
1991
).
26.
J. M. L.
Martin
,
Chem. Phys. Lett.
273
,
98
(
1997
);
see also
J. M. L.
Martin
and
P. R.
Taylor
,
J. Chem. Phys.
106
,
8620
(
1997
) for the original results on NH3.
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