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

Isomers of C2H3O

index Species CAS number Name Relative experimental enthalpy (kJ mol-1) sketch
a CH3CHO+ 75070 acetaldehyde cation   sketch of acetaldehyde cation
b CH3CO+ 3170692 acetyl cation   sketch of acetyl cation
c CH2COH+ 41084893 ketene, protonated   sketch of ketene, protonated
The calculated enthalpies include the calculated and scaled vibrational zero-point energy.
Methods with predefined basis sets
semi-empirical PM3
778.9 b
composite G1 NC
NC
NC
G2MP2 NC
NC
NC
G2 NC
NC
NC
G3 NC
NC
NC
G3B3 NC
NC
NC
G3MP2
NC
G4 NC
NC
NC
CBS-Q NC
NC
NC

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) TZVP cc-pVDZ cc-pVTZ cc-pVQZ aug-cc-pVDZ aug-cc-pVTZ aug-cc-pVQZ daug-cc-pVDZ daug-cc-pVTZ
hartree fock HF NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC NC
NC
ROHF   NC NC NC NC NC NC NC NC   NC NC NC NC NC NC NC NC NC NC
density functional LSDA
NC
NC

NC
NC

NC
NC

NC
NC

NC
NC

NC
NC

NC
NC

NC
NC

NC
NC

NC
NC

NC

NC

NC
NC

NC
NC

NC

NC
NC

NC
NC

NC
   
BLYP NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
  NC
NC
NC
NC
  NC NC
B1B95 NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC

NC
NC
NC
NC
NC
NC
NC

NC
   
B3LYP NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC NC
B3LYPultrafine   NC
NC
    NC
NC
NC
NC
NC
NC
NC
NC
NC
  NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
  NC
NC
NC
NC
NC
  NC NC
B3PW91 NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
  NC
NC
NC
NC
  NC NC
mPW1PW91 NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
  NC
NC
NC
NC
  NC NC
M06-2X NC
NC
NC NC
NC
NC NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
  NC
NC
NC
NC
NC
NC
  NC NC
NC
  NC NC
PBEPBE NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC

NC
NC
NC
NC
NC

NC
NC NC
PBEPBEultrafine   NC
NC
    NC
NC
NC
NC
NC
NC
NC
NC
  NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
  NC
NC
NC
NC
  NC NC
PBE1PBE NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
  NC
NC
NC
NC
  NC NC
HSEh1PBE NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
  NC
NC
NC
NC
  NC NC
TPSSh NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC NC
wB97X-D NC
NC
NC NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC NC
NC
NC
NC
NC
NC NC
B97D3 NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC  
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) TZVP cc-pVDZ cc-pVTZ cc-pVQZ aug-cc-pVDZ aug-cc-pVTZ aug-cc-pVQZ daug-cc-pVDZ daug-cc-pVTZ
Moller Plesset perturbation MP2 NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC NC
MP2=FULL NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC NC
ROMP2   NC NC NC NC NC NC NC NC NC NC NC NC NC   NC     NC NC
MP3         NC
NC
NC
  NC
NC
      NC
NC
NC
NC
NC
NC
NC
NC
        NC  
MP3=FULL   NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
  NC
NC
NC   NC  
MP4   NC
NC
NC
    NC
NC
NC
      NC
NC
NC
  NC
NC
NC
NC
NC
NC
NC
NC
  NC
NC
NC
NC
  NC  
MP4=FULL   NC
NC
    NC
NC
      NC
NC
  NC
NC
  NC
NC
    NC
NC
NC
NC
  NC  
B2PLYP NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
  NC
NC
NC
NC
  NC NC
B2PLYP=FULL NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
  NC
NC
NC
NC
  NC NC
Configuration interaction CID   NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
    NC
NC
NC
    NC
NC
  NC
NC
NC
NC
        NC  
CISD   NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
    NC
NC
NC
    NC
NC
  NC
NC
NC
NC
        NC  
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) TZVP cc-pVDZ cc-pVTZ cc-pVQZ aug-cc-pVDZ aug-cc-pVTZ aug-cc-pVQZ daug-cc-pVDZ daug-cc-pVTZ
Quadratic configuration interaction QCISD   NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
  NC
NC
    NC  
QCISD(T)         NC
NC
NC
    NC
NC
   
NC
NC
NC
NC
NC
NC

NC
NC
  NC
NC
NC
NC
NC
     
QCISD(T)=FULL         NC
NC
  NC
NC
      NC
NC
  NC
NC

NC
  NC
NC

NC
  NC  
Coupled Cluster CCD   NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
  NC
NC
NC

NC
  NC  
CCSD         NC
NC
NC
NC NC NC NC NC
NC
NC
NC
NC NC
NC
NC
NC
  NC
NC

NC
  NC  
CCSD=FULL         NC
NC
        NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
  NC
NC

NC
  NC  
CCSD(T)         NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC

NC
NC

NC
NC
NC
NC

NC
     
CCSD(T)=FULL         NC
NC
NC
          NC
NC
NC
NC
NC
NC

NC

NC
NC
NC

NC
     
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) TZVP cc-pVDZ cc-pVTZ cc-pVQZ aug-cc-pVDZ aug-cc-pVTZ aug-cc-pVQZ daug-cc-pVDZ daug-cc-pVTZ

Methods with effective core potentials (select basis sets)
CEP-31G CEP-31G* CEP-121G CEP-121G* LANL2DZ SDD cc-pVTZ-PP aug-cc-pVTZ-PP Def2TZVPP
hartree fock HF -74923.9 a
-73489.1 b
-73329.4 c
-75120.8 a
-73729.2 b
-73523.6 c
-74941.4 a
-73509.8 b
-73359.5 c
-75139.9 a
-73756.0 b
-73561.6 c
NC
NC
NC
NC
NC
NC
    NC
NC
NC
ROHF                 NC
density functional LSDA                
NC
BLYP                 NC
NC
B1B95                 NC
NC
B3LYP -76669.9 a
-75232.3 b
-75077.8 c
-76804.1 a
-75389.5 b
-75209.6 c
-76687.5 a
-75253.1 b
-75105.4 c
-76825.0 a
-75416.0 b
-75245.7 c
NC
NC
NC
NC
NC
NC
    NC
NC
NC
B3LYPultrafine                 NC
NC
B3PW91                 NC
NC
mPW1PW91                 NC
NC
M06-2X                 NC
NC
PBEPBE                 NC
NC
NC
PBEPBEultrafine                 NC
NC
PBE1PBE                 NC
NC
HSEh1PBE                 NC
NC
TPSSh                 NC
NC
wB97X-D -76673.9 a
-75079.2 c
-76813.5 a
-75217.2 c
-76691.4 a
-75108.1 c
-76833.7 a
-75254.4 c
NC
NC
NC
NC
    NC
NC
B97D3                 NC
NC
Moller Plesset perturbation MP2 -75508.9 a
-74225.4 b
-73997.5 c
-76060.8 a
-74777.7 b
-74547.3 c
-75601.6 a
-74322.9 b
-74103.9 c
-76151.3 a
-74871.4 b
-74651.6 c
NC
NC
NC
NC
NC
NC
    NC
NC
NC
MP2=FULL                 NC
NC
ROMP2                 NC
MP3                 NC
NC
MP3=FULL                 NC
NC
MP4                 NC
NC
MP4=FULL                 NC
NC
B2PLYP                 NC
NC
B2PLYP=FULL                 NC
NC
Configuration interaction CID                 NC
NC
CISD                 NC
NC
Quadratic configuration interaction QCISD                 NC
NC
QCISD(T)                 NC
NC
QCISD(T)=FULL                
NC
Coupled Cluster CCD                 NC
NC
CCSD                 NC
NC
CCSD=FULL                 NC
CCSD(T)                 NC
NC
CCSD(T)=FULL                
NC
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 Calculated; Vibrations; Scale Factors; Scale factors to list vibrational scaling factors.
See section Calculated; Vibrations; Scale Factors; Calculate a scale factor to calculate a vibrational scaling factor for a given set of molecules.