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IV.A.4. (XIV.F.)

Relative enthalpies of isomers - Comparison of 298.15K enthalpies (kJ mol-1)

Isomers of CHNO

index Species CAS number Name Relative experimental enthalpy (kJ mol-1) sketch
a HOCN 420053 cyanic acid   sketch of cyanic acid
b HCNO 506854 fulminic acid   sketch of fulminic acid
c HNCO 75138 Isocyanic acid 0.0 sketch of Isocyanic acid
The calculated enthalpies include the calculated and scaled vibrational zero-point energy.
Methods with predefined basis sets
semi-empirical AM1 104.9 a
284.4 b
0.0 c
PM3 68.8 a
193.1 b
0.0 c
PM6 88.1 a
190.6 b
0.0 c
MNDOd
0.0 c
composite G1 109.6 a
172.1 b
0.0 c
G2MP2 113.6 a
171.9 b
0.0 c
G2 112.5 a
174.0 b
0.0 c
G3 111.4 a
171.1 b
0.0 c
G3B3 103.4 a
284.1 b
0.0 c
G3MP2 111.0 a
172.1 b
0.0 c
G4 103.7 a
281.6 b
0.0 c
CBS-Q 109.8 a
291.8 b
0.0 c
molecular mechanics MM3
0.0 c

Methods with standard basis sets
STO-3G 3-21G 3-21G* 6-31G 6-31G* 6-31G** 6-31+G** 6-311G* 6-311G** 6-31G(2df,p) 6-311+G(3df,2p) cc-pVDZ cc-pVTZ cc-pVQZ aug-cc-pVDZ aug-cc-pVTZ cc-pV(T+d)Z
hartree fock HF -19.8 a
289.4 b
0.0 c
84.2 a
347.1 b
0.0 c
84.2 a
347.1 b
0.0 c
85.8 a
325.2 b
0.0 c

  b
99.6 a
350.0 b
0.0 c

  b
110.5 a
352.2 b
0.0 c
101.8 a
355.4 b
0.0 c
104.8 a
351.1 b
0.0 c
105.7 a
351.5 b
0.0 c
102.2 a
351.3 b
0.0 c
103.5 a
350.1 b
0.0 c
104.0 a
350.4 b
0.0 c
103.0 a
351.3 b
0.0 c
103.8 a
349.3 b
0.0 c
103.5 a
350.1 b
0.0 c
density functional LSDA 87.1 a
224.6 b
0.0 c
138.2 a
267.6 b
0.0 c
138.2 a
267.6 b
0.0 c
138.2 a
248.3 b
0.0 c
136.0 a
248.2 b
0.0 c
131.4 a
252.6 b
0.0 c
129.1 a
254.6 b
0.0 c
143.1 a
259.0 b
0.0 c
134.8 a
262.5 b
0.0 c
133.5 a
254.5 b
0.0 c
  131.5 a
249.2 b
0.0 c
132.4 a
257.9 b
0.0 c
  129.7 a
257.7 b
0.0 c
  132.4 a
257.9 b
0.0 c
BLYP 69.4 a
223.9 b
0.0 c
120.7 a
262.0 b
0.0 c
120.7 a
262.0 b
0.0 c
122.9 a
245.1 b
0.0 c
126.7 a
254.6 b
0.0 c
122.1 a
259.2 b
0.0 c
120.1 a
260.3 b
0.0 c
131.9 a
263.8 b
0.0 c
124.5 a
266.4 b
0.0 c
124.1 a
261.5 b
0.0 c
 
0.0 c

0.0 c
 
0.0 c
 
0.0 c
B1B95 54.0 a
247.5 b
0.0 c
116.0 a
288.9 b
0.0 c
116.0 a
288.9 b
0.0 c
116.8 a
267.8 b
0.0 c
112.1 a
265.3 b
0.0 c
117.9 a
281.0 b
0.0 c
116.4 a
280.5 b
0.0 c
128.6 a
285.1 b
0.0 c
120.4 a
287.9 b
0.0 c

0.0 c
  118.6 a
279.4 b
0.0 c
108.3 a
272.8 b
0.0 c
 
0.0 c
  108.3 a
272.8 b
0.0 c
B3LYP 53.5 a
245.3 b
0.0 c
115.2 a
283.7 b
0.0 c
115.2 a
283.7 b
0.0 c
116.8 a
264.8 b
0.0 c
122.7 a
276.1 b
0.0 c
117.9 a
280.8 b
0.0 c
116.3 a
280.6 b
0.0 c
128.2 a
285.0 b
0.0 c
120.3 a
287.5 b
0.0 c
120.5 a
282.9 b
0.0 c

0.0 c
117.8 a
277.7 b
0.0 c
119.8 a
285.5 b
0.0 c
  117.3 a
284.8 b
0.0 c
119.7 a
285.1 b
0.0 c
119.8 a
285.5 b
0.0 c
B3LYPultrafine         122.7 a
276.1 b
0.0 c
                       
B3PW91 58.6 a
245.9 b
0.0 c
119.3 a
287.6 b
0.0 c
119.3 a
287.6 b
0.0 c
119.8 a
266.6 b
0.0 c
125.9 a
274.6 b
0.0 c
120.9 a
279.5 b
0.0 c
119.2 a
278.8 b
0.0 c
131.9 a
283.8 b
0.0 c
123.7 a
286.4 b
0.0 c
123.1 a
281.3 b
0.0 c
  121.7 a
277.6 b
0.0 c
122.7 a
283.1 b
0.0 c
 
0.0 c
  122.7 a
283.1 b
0.0 c
mPW1PW91 54.3 a
251.0 b
0.0 c
114.2 a
289.8 b
0.0 c
117.5 a
293.0 b
0.0 c
118.0 a
271.2 b
0.0 c
122.0 a
276.0 b
0.0 c
116.8 a
281.0 b
0.0 c
115.4 a
280.3 b
0.0 c
128.1 a
285.2 b
0.0 c
122.6 a
290.9 b
0.0 c
122.2 a
285.8 b
0.0 c
  117.9 a
279.4 b
0.0 c
118.9 a
284.3 b
0.0 c
 
0.0 c
  118.9 a
284.3 b
0.0 c
PBEPBE 77.0 a
225.5 b
0.0 c
126.0 a
265.4 b
0.0 c
126.0 a
265.5 b
0.0 c
127.6 a
246.4 b
0.0 c
131.2 a
251.4 b
0.0 c
126.4 a
256.1 b
0.0 c
124.3 a
256.8 b
0.0 c
136.9 a
260.4 b
0.0 c
128.9 a
263.4 b
0.0 c
127.9 a
258.0 b
0.0 c

0.0 c
126.8 a
253.0 b
0.0 c
127.2 a
261.3 b
0.0 c
 
0.0 c
127.0 a
261.4 b
0.0 c
127.2 a
261.3 b
0.0 c
Moller Plesset perturbation MP2 -2.9 a
225.5 b
0.0 c
88.4 a
283.7 b
0.0 c
88.4 a
283.7 b
0.0 c
87.2 a
261.9 b
0.0 c

  b
101.0 a
277.4 b
0.0 c

  b
113.1 a
276.4 b
0.0 c
101.4 a
282.4 b
0.0 c
106.7 a
278.4 b
0.0 c
  101.0 a
275.8 b
0.0 c
103.9 a
0.0 c
  103.3 a
279.3 b
0.0 c
  103.9 a
277.9 b
0.0 c
MP2=FULL NC
NC
  a
  b
  a
  b
87.3 a
261.8 b
0.0 c
106.2 a
271.6 b
0.0 c
101.7 a
277.5 b
0.0 c
100.7 a
274.9 b
0.0 c
113.5 a
276.3 b
0.0 c
101.9 a
282.2 b
0.0 c
NC
NC
  101.5 a
275.8 b
0.0 c
105.9 a
0.0 c
 
0.0 c
  105.9 a
275.6 b
0.0 c
MP3        
0.0 c
                       
MP4        
0.0 c
                       
Configuration interaction CID   NC
NC
NC
NC
NC
NC
NC
NC
    NC
NC
                 
CISD   81.8 a
302.4 b
0.0 c
NC
NC
NC
NC
103.1 a
307.3 b
0.0 c
    NC
NC
                 
Quadratic configuration interaction QCISD NC
NC
79.6 a
281.3 b
0.0 c
79.6 a
281.3 b
0.0 c
79.9 a
261.4 b
0.0 c
99.9 a
287.8 b
0.0 c
95.4 a
293.8 b
0.0 c
93.8 a
290.6 b
0.0 c
107.2 a
295.7 b
0.0 c
96.2 a
301.1 b
0.0 c
NC
NC
  96.5 a
295.0 b
0.0 c
98.9 a
298.4 b
0.0 c
      98.9 a
298.4 b
0.0 c
QCISD(T)        
0.0 c
                       
Coupled Cluster CCD NC
NC
67.6 a
287.3 b
0.0 c
67.6 a
287.4 b
0.0 c
68.9 a
267.3 b
0.0 c
93.0 a
293.7 b
0.0 c
88.6 a
299.8 b
0.0 c
87.9 a
296.6 b
0.0 c
100.4 a
300.1 b
0.0 c
NC
NC
NC
NC
  89.5 a
299.1 b
0.0 c
93.8 a
0.0 c
      93.8 a
0.0 c
CCSD        
0.0 c
                       
CCSD(T)        
279.9 b
0.0 c
             
NC
     
NC

Methods with effective core potentials (select basis sets)
CEP-31G CEP-31G* CEP-121G CEP-121G* LANL2DZ SDD
hartree fock HF 78.7 a
300.8 b
0.0 c
104.4 a
343.0 b
0.0 c
75.9 a
301.6 b
0.0 c
100.8 a
341.7 b
0.0 c
83.5 a
314.3 b
0.0 c
83.8 a
314.7 b
0.0 c
density functional B1B95 114.1 a
258.4 b
0.0 c
121.0 a
276.6 b
0.0 c
       
B3LYP 107.4 a
252.6 b
0.0 c
118.3 a
280.0 b
0.0 c
105.0 a
252.6 b
0.0 c
116.6 a
281.0 b
0.0 c
113.8 a
258.2 b
0.0 c
114.0 a
258.5 b
0.0 c
Moller Plesset perturbation MP2 78.3 a
250.0 b
0.0 c
103.5 a
275.4 b
0.0 c
75.7 a
249.9 b
0.0 c
101.4 a
274.1 b
0.0 c
82.5 a
255.0 b
0.0 c
82.3 a
255.1 b
0.0 c

Single point energy calculations (select basis sets)
6-311+G(3df,2p) cc-pVDZ cc-pVTZ aug-cc-pVDZ aug-cc-pVTZ cc-pV(T+d)Z
Moller Plesset perturbation MP2FC// HF/6-31G* 117.1 a
171.6 b
0.0 c

0.0 c
112.8 a
171.6 b
0.0 c

0.0 c

0.0 c
112.8 a
171.6 b
0.0 c
MP2FC// B3LYP/6-31G* 109.0 a
283.5 b
0.0 c
103.3 a
285.1 b
0.0 c
104.6 a
283.6 b
0.0 c

0.0 c

0.0 c
104.6 a
283.6 b
0.0 c
MP2FC// MP2FC/6-31G*
0.0 c

0.0 c
103.3 a
278.5 b
0.0 c
102.4 a
279.5 b
0.0 c
  103.3 a
278.5 b
0.0 c
MP4// HF/6-31G* 118.6 a
166.0 b
0.0 c

0.0 c
26.6 a
78.4 b
0.0 c
    26.6 a
78.4 b
0.0 c
MP4// B3LYP/6-31G*   107.5 a
281.3 b
0.0 c
107.8 a
279.1 b
0.0 c
    107.8 a
279.1 b
0.0 c
MP4// MP2/6-31G*
0.0 c
  106.9 a
272.8 b
0.0 c
    106.9 a
272.8 b
0.0 c
Coupled Cluster CCSD// HF/6-31G*
0.0 c

0.0 c

0.0 c

0.0 c

0.0 c

0.0 c
CCSD(T)// HF/6-31G*
0.0 c

0.0 c

0.0 c

0.0 c

0.0 c

0.0 c
CCSD// B3LYP/6-31G* 99.4 a
301.3 b
0.0 c

0.0 c

0.0 c
   
0.0 c
CCSD(T)// B3LYP/6-31G* 104.1 a
290.9 b
0.0 c

0.0 c

0.0 c
   
0.0 c
CCSD(T)//B3LYP/6-31G(2df,p)     100.4 a
290.2 b
0.0 c
    100.4 a
290.2 b
0.0 c
CCSD// MP2FC/6-31G*
0.0 c

0.0 c

0.0 c
93.2 a
303.0 b
0.0 c
 
0.0 c
CCSD(T)// MP2FC/6-31G*
0.0 c

0.0 c

0.0 c
97.3 a
289.6 b
0.0 c
 
0.0 c
NC = not calculated
For descriptions of the methods (AM1, HF, MP2, ...) and basis sets (3-21G, 3-21G*, 6-31G, ...) see the glossary in section I.C. Predefined means the basis set used is determined by the method.
gaw refers to the group additivity method implemeted in the NIST Chemistry Webbook.

See section III.C.1 List or set vibrational scaling factors to change the scale factors used here.
See section III.C.2 Calculate a vibrational scaling factor for a given set of molecules to determine the least squares best scaling factor.