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

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

Isomers of C4H6O2

index Species CAS number Name Relative experimental enthalpy (kJ mol-1) sketch
a C4H6O2 107937 Crotonic Acid   sketch of Crotonic Acid
b C4H6O2 96480 γ–Butyrolactone 0.0 sketch of γ–Butyrolactone
c C4H6O2 96333 2-Propenoic acid, methyl ester 33.5 sketch of 2-Propenoic acid, methyl ester
d C4H6O2 431038 2,3-Butanedione 39.7 sketch of 2,3-Butanedione
The calculated enthalpies include the calculated and scaled vibrational zero-point energy.
Methods with predefined basis sets
semi-empirical AM1
0.0 b
89.4 c
785.0 d
PM3
0.0 b
93.0 c
506.8 d
PM6
0.0 b
76.5 c
486.2 d
MNDOd
0.0 b
106.1 c
composite G1 -554.2 a
0.0 b
37.3 c
262.0 d
G2MP2 -553.3 a
0.0 b
39.5 c
261.6 d
G2 -554.0 a
0.0 b
39.5 c
261.1 d
G3 -556.6 a
0.0 b
38.4 c
262.1 d
G3B3 2.7 a
0.0 b
55.3 c
26.7 d
G3MP2
0.0 b
36.8 c
261.1 d
G4 3.0 a
0.0 b
55.9 c
25.9 d
CBS-Q NC
NC
molecular mechanics MM3
0.0 b
56.9 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 aug-cc-pVDZ aug-cc-pVTZ cc-pV(T+d)Z
hartree fock HF
0.0 b
191.3 c

0.0 b
49.8 c

0.0 b
49.8 c

0.0 b
34.6 c
 
0.0 b
57.7 c
 
0.0 b
54.9 c

0.0 b
51.7 c

0.0 b
59.0 c

0.0 b
53.2 c

0.0 b
52.5 c

0.0 b
52.2 c

0.0 b
60.3 c

0.0 b
53.1 c

0.0 b
52.2 c
density functional LSDA
0.0 b
180.5 c

0.0 b
101.0 c

0.0 b
101.0 c

0.0 b
86.5 c

0.0 b
102.0 c

0.0 b
100.8 c

0.0 b
97.6 c

0.0 b
97.6 c

0.0 b
93.7 c

0.0 b
102.4 c
 
0.0 b
100.5 c

0.0 b
93.8 c

0.0 b
102.2 c
 
0.0 b
93.8 c
BLYP
0.0 b
137.6 c

0.0 b
 
0.0 b
34.4 c

0.0 b
48.6 c

0.0 b
47.6 c

0.0 b
43.3 c
 
0.0 b
39.3 c

0.0 b
48.0 c
 
0.0 b
46.7 c

0.0 b
38.3 c

0.0 b
49.3 c
 
0.0 b
38.3 c
B1B95
0.0 b
167.6 c

0.0 b
78.8 c

0.0 b
78.8 c

0.0 b
60.3 c

0.0 b
78.5 c

0.0 b
75.6 c

0.0 b
72.5 c

0.0 b
72.8 c

0.0 b
69.5 c

0.0 b
77.6 c
 
0.0 b
74.8 c

0.0 b
72.3 c

0.0 b
 
0.0 b
72.3 c
B3LYP
0.0 b
156.8 c

0.0 b
60.7 c

0.0 b
60.7 c

0.0 b
44.3 c

0.0 b
60.7 c

0.0 b
59.5 c

0.0 b
55.2 c

0.0 b
54.4 c

0.0 b
51.3 c

0.0 b
59.6 c

0.0 b
51.6 c

0.0 b
57.9 c

0.0 b
50.6 c

0.0 b
60.6 c
 
0.0 b
50.6 c
B3LYPultrafine        
0.0 b
60.6 c
                     
B3PW91
0.0 b
170.1 c

0.0 b
80.9 c

0.0 b
80.9 c

0.0 b
62.1 c

0.0 b
79.2 c

0.0 b
77.8 c

0.0 b
74.7 c

0.0 b
74.4 c

0.0 b
71.0 c

0.0 b
78.3 c
 
0.0 b
76.4 c

0.0 b
71.4 c

0.0 b
80.1 c
 
0.0 b
71.4 c
mPW1PW91
0.0 b
176.8 c

0.0 b
85.5 c

0.0 b
85.8 c

0.0 b
66.9 c

0.0 b
84.0 c

0.0 b
82.5 c

0.0 b
79.4 c

0.0 b
79.3 c

0.0 b
75.7 c

0.0 b
83.1 c
 
0.0 b
80.8 c

0.0 b
76.3 c

0.0 b
84.9 c
 
0.0 b
76.3 c
PBEPBE
0.0 b
159.4 c

0.0 b
80.4 c

0.0 b
80.4 c

0.0 b
60.9 c

0.0 b
76.1 c

0.0 b
74.8 c

0.0 b
71.4 c

0.0 b
71.5 c

0.0 b
68.0 c

0.0 b
75.9 c

0.0 b
69.2 c

0.0 b
73.7 c

0.0 b
68.3 c

0.0 b
76.8 c
 
0.0 b
68.3 c
PBEPBEultrafine        
0.0 b
76.1 c
                     
Moller Plesset perturbation MP2
0.0 b
143.8 c

0.0 b
55.9 c

0.0 b
55.9 c

0.0 b
41.8 c
 
0.0 b
73.8 c
 
0.0 b
75.1 c

0.0 b
74.5 c

0.0 b
80.1 c
 
0.0 b
73.0 c
       
MP2=FULL        
0.0 b
74.7 c
   
0.0 b
76.3 c

0.0 b
75.7 c
             
MP3        
0.0 b
71.6 c
                     

Methods with effective core potentials (select basis sets)
CEP-31G CEP-31G* CEP-121G CEP-121G* LANL2DZ SDD
hartree fock HF
0.0 b
46.8 c

0.0 b
72.2 c

0.0 b
45.7 c

0.0 b
62.6 c

0.0 b
41.9 c

0.0 b
42.6 c
density functional B1B95
0.0 b
75.9 c

0.0 b
94.4 c
       
B3LYP
0.0 b
54.8 c

0.0 b
71.8 c

0.0 b
49.5 c

0.0 b
61.5 c

0.0 b
51.4 c

0.0 b
51.2 c
Moller Plesset perturbation MP2
0.0 b
48.8 c

0.0 b
85.3 c

0.0 b
43.8 c

0.0 b
75.6 c

0.0 b
41.9 c

0.0 b
42.3 c

Single point energy calculations (select basis sets)
cc-pVDZ cc-pVTZ aug-cc-pVDZ cc-pV(T+d)Z
Moller Plesset perturbation MP2FC// HF/6-31G*
0.0 b
190.7 c

0.0 b
168.9 c
 
0.0 b
168.9 c
MP2FC// B3LYP/6-31G*
0.0 b
73.1 c
     
MP2FC// MP2FC/6-31G*    
0.0 b
75.2 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.