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

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

Isomers of C2H2O

index Species CAS number Name Relative experimental enthalpy (kJ mol-1) sketch
a C2H2O 157186 Oxirene   sketch of Oxirene
b HCCOH 32038792 ethynol   sketch of ethynol
c CH2CO 463514 Ketene 0.0 sketch of Ketene
The calculated enthalpies include the calculated and scaled vibrational zero-point energy.
Methods with predefined basis sets
semi-empirical AM1 376.0 a
184.7 b
0.0 c
PM3 257.9 a
101.2 b
0.0 c
PM6 291.7 a
169.6 b
0.0 c
MNDOd
0.0 c
composite G1
149.8 b
0.0 c
G2MP2
151.2 b
0.0 c
G2 134.8 a
151.6 b
0.0 c
G3 139.1 a
148.2 b
0.0 c
G3B3 235.5 a
141.1 b
0.0 c
G3MP2
147.9 b
0.0 c
G4 306.1 a
142.2 b
0.0 c
CBS-Q 316.5 a
141.8 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
89.7 b
0.0 c

132.5 b
0.0 c

132.5 b
0.0 c

132.8 b
0.0 c
 
154.9 b
0.0 c
 
168.6 b
0.0 c

152.4 b
0.0 c

156.5 b
0.0 c

152.9 b
0.0 c

159.9 b
0.0 c

151.7 b
0.0 c

151.3 b
0.0 c

154.6 b
0.0 c

150.9 b
0.0 c

151.7 b
0.0 c
density functional LSDA
167.1 b
0.0 c

164.2 b
0.0 c

164.2 b
0.0 c

163.5 b
0.0 c

173.8 b
0.0 c

163.3 b
0.0 c

155.8 b
0.0 c

172.0 b
0.0 c

156.5 b
0.0 c

158.6 b
0.0 c
 
162.3 b
0.0 c

151.9 b
0.0 c
 
153.1 b
0.0 c
 
151.9 b
0.0 c
BLYP
167.5 b
0.0 c

171.7 b
0.0 c

171.7 b
0.0 c

170.8 b
0.0 c

182.5 b
0.0 c

172.1 b
0.0 c

163.9 b
0.0 c

178.8 b
0.0 c

164.8 b
0.0 c

167.7 b
0.0 c
 
170.0 b
0.0 c

160.7 b
0.0 c
 
0.0 c
 
160.7 b
0.0 c
B1B95
151.3 b
0.0 c

159.2 b
0.0 c

159.2 b
0.0 c

158.3 b
0.0 c

0.0 c

163.7 b
0.0 c

157.6 b
0.0 c

174.4 b
0.0 c

159.1 b
0.0 c

160.3 b
0.0 c
 
164.6 b
0.0 c

154.7 b
0.0 c
 
156.2 b
0.0 c
 
154.7 b
0.0 c
B3LYP
151.4 b
0.0 c

162.0 b
0.0 c

162.1 b
0.0 c

160.8 b
0.0 c

176.9 b
0.0 c

166.0 b
0.0 c

158.8 b
0.0 c

174.3 b
0.0 c

159.6 b
0.0 c

0.0 c

0.0 c

165.4 b
0.0 c

156.2 b
0.0 c
 
157.0 b
0.0 c

154.3 b
0.0 c

156.2 b
0.0 c
B3LYPultrafine        
176.9 b
0.0 c
                       
B3PW91
155.9 b
0.0 c

162.2 b
0.0 c

162.2 b
0.0 c

161.5 b
0.0 c

177.3 b
0.0 c

166.0 b
0.0 c

160.1 b
0.0 c

176.5 b
0.0 c

161.1 b
0.0 c

162.7 b
0.0 c
 
166.9 b
0.0 c

157.5 b
0.0 c
 
0.0 c
 
157.5 b
0.0 c
mPW1PW91
151.8 b
0.0 c

156.8 b
0.0 c

159.9 b
0.0 c

159.5 b
0.0 c

173.5 b
0.0 c

161.9 b
0.0 c

156.1 b
0.0 c

173.2 b
0.0 c

160.3 b
0.0 c

161.9 b
0.0 c
 
163.3 b
0.0 c

153.9 b
0.0 c
 
0.0 c
 
153.9 b
0.0 c
PBEPBE
172.7 b
0.0 c

172.4 b
0.0 c

172.5 b
0.0 c

172.3 b
0.0 c

183.4 b
0.0 c

172.4 b
0.0 c

165.2 b
0.0 c

181.6 b
0.0 c

166.5 b
0.0 c

168.2 b
0.0 c

0.0 c

171.9 b
0.0 c

161.7 b
0.0 c
 
0.0 c

159.5 b
0.0 c

161.7 b
0.0 c
Moller Plesset perturbation MP2
111.5 b
0.0 c

146.9 b
0.0 c

146.9 b
0.0 c

142.3 b
0.0 c
 
153.6 b
0.0 c
 
166.2 b
0.0 c

147.7 b
0.0 c

148.1 b
0.0 c
 
155.9 b
0.0 c

  b
 
148.2 b
0.0 c
 
142.3 b
0.0 c
MP2=FULL
NC

146.8 b
0.0 c

NC

NC

  b

153.7 b
0.0 c

148.6 b
0.0 c

166.0 b
0.0 c

147.5 b
0.0 c

NC
 
156.0 b
0.0 c

  b
     
NC
MP3        
0.0 c
                       
MP4
NC

NC
   
171.3 b
0.0 c
     
NC

NC
             
Configuration interaction CID  
NC
   
160.2 b
0.0 c
       
NC
             
CISD  
  b
   
162.7 b
0.0 c
                       
Quadratic configuration interaction QCISD
NC

138.2 b
0.0 c
 
NC

160.9 b
0.0 c

153.3 b
0.0 c

147.9 b
0.0 c

166.4 b
0.0 c

149.0 b
0.0 c

NC
 
157.7 b
0.0 c

NC
     
NC
QCISD(T)        
161.9 b
0.0 c
     
NC
     
NC
     
NC
Coupled Cluster CCD
NC

NC
 
NC

154.2 b
0.0 c

NC

NC

NC

NC

NC
 
151.1 b
0.0 c

NC
     
NC
CCSD        
157.2 b
0.0 c
     
NC
     
NC
     
NC
CCSD(T)        
160.8 b
0.0 c

0.0 c
   
NC
     
NC
     
NC

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

182.0 b
0.0 c

118.5 b
0.0 c

157.7 b
0.0 c

120.0 b
0.0 c

119.5 b
0.0 c
density functional B1B95
158.1 b
0.0 c

179.1 b
0.0 c
       
B3LYP
162.8 b
0.0 c

184.1 b
0.0 c

148.1 b
0.0 c

167.0 b
0.0 c

148.6 b
0.0 c

149.1 b
0.0 c
Moller Plesset perturbation MP2
146.2 b
0.0 c

172.9 b
0.0 c

132.3 b
0.0 c

157.2 b
0.0 c

130.4 b
0.0 c

130.4 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*
149.9 b
0.0 c

0.0 c

148.5 b
0.0 c

0.0 c

0.0 c

148.5 b
0.0 c
MP2FC// B3LYP/6-31G*
143.1 b
0.0 c

157.4 b
0.0 c

141.9 b
0.0 c

0.0 c

0.0 c

141.9 b
0.0 c
MP2FC// MP2FC/6-31G*
0.0 c

0.0 c

56.1 b
0.0 c

63.5 b
0.0 c
 
56.1 b
0.0 c
MP4// HF/6-31G*
158.0 b
0.0 c

0.0 c

156.1 b
0.0 c
   
156.1 b
0.0 c
MP4// B3LYP/6-31G*  
167.5 b
0.0 c

151.0 b
0.0 c
   
151.0 b
0.0 c
MP4// MP2/6-31G*
0.0 c
 
65.5 b
0.0 c
   
65.5 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*
142.3 b
0.0 c

0.0 c

0.0 c
   
0.0 c
CCSD(T)// B3LYP/6-31G*
144.8 b
0.0 c

0.0 c

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

0.0 c

0.0 c

61.7 b
0.0 c
 
0.0 c
CCSD(T)// MP2FC/6-31G*
0.0 c

0.0 c

0.0 c

64.5 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.