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

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

Isomers of C4H4

index Species CAS number Name Relative experimental enthalpy (kJ mol-1) sketch
a C4H4 1120532 cyclobutadiene   sketch of cyclobutadiene
b H2CCCCH2 2873509 Butatriene   sketch of Butatriene
c C2H3CCH 689974 1-Buten-3-yne 0.0 sketch of 1-Buten-3-yne
The calculated enthalpies include the calculated and scaled vibrational zero-point energy.
Methods with predefined basis sets
semi-empirical AM1
34.2 b
0.0 c
PM3
48.1 b
0.0 c
PM6 152.4 a
-17.9 b
0.0 c
composite G1
28.8 b
0.0 c
G2MP2
28.0 b
0.0 c
G2
27.6 b
0.0 c
G3
27.2 b
0.0 c
G3B3
30.5 b
0.0 c
G3MP2
25.9 b
0.0 c
molecular mechanics MM3
-65.6 b
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
82.0 b
0.0 c
42.8 b
0.0 c
42.8 b
0.0 c
41.4 b
0.0 c
44.2 b
0.0 c
44.3 b
0.0 c 		 
45.5 b
0.0 c
47.3 b
0.0 c
42.8 b
0.0 c
45.7 b
0.0 c
44.1 b
0.0 c
46.1 b
0.0 c
44.8 b
0.0 c
46.0 b
0.0 c
46.1 b
0.0 c
density functional LSDA
11.9 b
0.0 c
-0.1 b
0.0 c
-0.1 b
0.0 c
-2.7 b
0.0 c
-5.5 b
0.0 c
-4.8 b
0.0 c
-2.0 b
0.0 c
-1.4 b
0.0 c
0.5 b
0.0 c
-4.1 b
0.0 c 		 
-1.4 b
0.0 c
0.7 b
0.0 c
0.9 b
0.0 c 		 
0.7 b
0.0 c
BLYP
15.3 b
0.0 c
3.6 b
0.0 c
3.6 b
0.0 c
0.5 b
0.0 c
-2.4 b
0.0 c
-1.5 b
0.0 c
1.5 b
0.0 c
1.8 b
0.0 c
3.8 b
0.0 c
-1.4 b
0.0 c 		 
2.2 b
0.0 c
3.5 b
0.0 c
4.7 b
0.0 c 		 
3.5 b
0.0 c
B1B95
28.6 b
0.0 c
13.3 b
0.0 c
0.0 c
10.1 b
0.0 c
9.1 b
0.0 c
8.4 b
0.0 c
10.7 b
0.0 c
11.1 b
0.0 c
12.9 b
0.0 c
8.6 b
0.0 c 		 
10.6 b
0.0 c
0.0 c
0.0 c 		 
0.0 c
B3LYP
28.2 b
0.0 c
11.9 b
0.0 c
11.9 b
0.0 c
9.1 b
0.0 c
6.9 b
0.0 c
7.6 b
0.0 c
10.2 b
0.0 c
10.6 b
0.0 c
12.6 b
0.0 c
7.4 b
0.0 c
12.2 b
0.0 c
10.6 b
0.0 c
12.2 b
0.0 c
12.3 b
0.0 c
12.5 b
0.0 c
-145.2 b
0.0 c
B3LYPultrafine        
6.9 b
0.0 c 		                     
B3PW91
-142.4 b
0.0 c
11.7 b
0.0 c
11.7 b
0.0 c
8.7 b
0.0 c
6.5 b
0.0 c
7.1 b
0.0 c
9.4 b
0.0 c
9.7 b
0.0 c
11.5 b
0.0 c
7.4 b
0.0 c 		 
9.5 b
0.0 c
11.0 b
0.0 c
10.9 b
0.0 c 		 
11.0 b
0.0 c
mPW1PW91
30.6 b
0.0 c
14.0 b
0.0 c
14.2 b
0.0 c
11.1 b
0.0 c
8.9 b
0.0 c
9.5 b
0.0 c
11.9 b
0.0 c
12.0 b
0.0 c
13.8 b
0.0 c
9.8 b
0.0 c 		 
11.8 b
0.0 c
13.3 b
0.0 c
13.1 b
0.0 c 		 
13.3 b
0.0 c
PBEPBE
14.1 b
0.0 c
3.3 b
0.0 c
3.3 b
0.0 c
-0.1 b
0.0 c
-3.0 b
0.0 c
-2.2 b
0.0 c
0.7 b
0.0 c
0.6 b
0.0 c
2.6 b
0.0 c
-1.6 b
0.0 c
2.4 b
0.0 c
0.8 b
0.0 c
2.3 b
0.0 c
2.6 b
0.0 c
2.8 b
0.0 c
2.3 b
0.0 c
PBEPBEultrafine        
-3.0 b
0.0 c 		                     
Moller Plesset perturbation MP2FC
113.7 b
0.0 c
62.4 b
0.0 c
62.4 b
0.0 c
  b 		 
48.8 b
0.0 c
49.9 b
0.0 c
49.9 b
0.0 c
50.0 b
0.0 c
45.1 b
0.0 c 		 
48.0 b
0.0 c
46.7 b
0.0 c
48.5 b
0.0 c 		 
46.7 b
0.0 c
MP2FU  
62.2 b
0.0 c
62.2 b
0.0 c
62.6 b
0.0 c
49.2 b
0.0 c
48.2 b
0.0 c
49.3 b
0.0 c
49.4 b
0.0 c
49.7 b
0.0 c 		   
47.5 b
0.0 c
45.2 b
0.0 c 		   
45.2 b
0.0 c
MP3        
37.0 b
0.0 c 		                     
MP4  
NC		    
NC		                      
Configuration interaction CID    
45.8 b
0.0 c
44.3 b
0.0 c
41.2 b
0.0 c 		   
42.3 b
0.0 c 		               
CISD    
45.1 b
0.0 c
43.5 b
0.0 c
40.8 b
0.0 c 		   
42.0 b
0.0 c 		               
Quadratic configuration interaction QCISD  
41.3 b
0.0 c
41.3 b
0.0 c
39.8 b
0.0 c
36.9 b
0.0 c
36.2 b
0.0 c 		 
38.2 b
0.0 c 		     
35.7 b
0.0 c 		       
Coupled Cluster CCD  
43.7 b
0.0 c
43.7 b
0.0 c
0.0 c
38.9 b
0.0 c
38.0 b
0.0 c 		 
40.0 b
0.0 c 		     
37.1 b
0.0 c 		       
CCSD(T)        
32.5 b
0.0 c 		                     
Methods with effective core potentials (select basis sets)
CEP-31G CEP-31G* CEP-121G CEP-121G* LANL2DZ SDD
hartree fock HF
54.7 b
0.0 c
53.1 b
0.0 c
49.3 b
0.0 c
49.5 b
0.0 c
47.0 b
0.0 c
47.3 b
0.0 c
density functional B1B95
23.0 b
0.0 c
20.3 b
0.0 c 		       
B3LYP
23.3 b
0.0 c
20.3 b
0.0 c
16.5 b
0.0 c
13.7 b
0.0 c
14.7 b
0.0 c
14.7 b
0.0 c
Moller Plesset perturbation MP2FC
69.8 b
0.0 c
59.9 b
0.0 c
66.7 b
0.0 c
54.3 b
0.0 c
62.6 b
0.0 c
62.7 b
0.0 c
Single point energy calculations (select basis sets)
6-311+G(3df,2p) cc-pVDZ cc-pVTZ aug-cc-pVDZ cc-pV(T+d)Z
Moller Plesset perturbation MP2FC// HF/6-31G*
42.5 b
0.0 c 		 
42.4 b
0.0 c 		 
42.4 b
0.0 c
MP2FC// B3LYP/6-31G*
46.9 b
0.0 c
46.9 b
0.0 c
46.9 b
0.0 c 		 
46.9 b
0.0 c
MP2FC// MP2FC/6-31G*
48.0 b
0.0 c 		 
48.0 b
0.0 c
50.1 b
0.0 c
48.0 b
0.0 c
MP4// HF/6-31G*
33.4 b
0.0 c 		 
33.2 b
0.0 c 		 
33.2 b
0.0 c
MP4// B3LYP/6-31G*  
36.1 b
0.0 c
36.8 b
0.0 c 		 
36.8 b
0.0 c
MP4// MP2/6-31G*
38.0 b
0.0 c 		 
37.8 b
0.0 c 		 
37.8 b
0.0 c
Coupled Cluster CCSD// HF/6-31G*    
35.5 b
0.0 c 		 
35.5 b
0.0 c
CCSD(T)// HF/6-31G*    
30.6 b
0.0 c 		 
30.6 b
0.0 c
CCSD// B3LYP/6-31G*
37.7 b
0.0 c 		       
CCSD(T)// B3LYP/6-31G*
33.6 b
0.0 c 		       
CCSD(T)//B3LYP/6-31G(2df,p)    
32.7 b
0.0 c 		 
32.7 b
0.0 c
CCSD// MP2FC/6-31G*
37.7 b
0.0 c 		   
39.3 b
0.0 c 		 
CCSD(T)// MP2FC/6-31G*
34.0 b
0.0 c 		   
35.8 b
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.