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

Isomers of C5H8O

index Species CAS number Name Relative experimental enthalpy (kJ mol-1) sketch
a C5H8O 120923 Cyclopentanone 0.0 sketch of Cyclopentanone
b C5H8O 1487156 Furan, 2,3-dihydro-5-methyl- 61.9 sketch of Furan, 2,3-dihydro-5-methyl-
c C5H8O 765435 Methyl cyclopropyl ketone 76.8 sketch of Methyl cyclopropyl ketone
d C5H8O 110872 2H-Pyran, 3,4-dihydro- 79.3 sketch of 2H-Pyran, 3,4-dihydro-
The calculated enthalpies include the calculated and scaled vibrational zero-point energy.
Methods with predefined basis sets
semi-empirical AM1
  b
  d
PM6
  b
  d
MNDOd
-167.2 b
-165.1 d
composite G1 0.0 a
68.4 b
70.7 c
81.1 d
G2MP2 0.0 a
70.1 b
69.2 c
81.9 d
G2 0.0 a
70.4 b
69.1 c
82.7 d
G3 0.0 a
69.4 b
70.6 c
81.1 d
G3B3 0.0 a
68.4 b
70.3 c
79.7 d
G3MP2
NC
NC
G4 0.0 a
67.8 b
67.5 c
79.5 d
CBS-Q 0.0 a
68.6 c
Group additivity gaw
-125.0 b
-125.0 d
molecular mechanics MM3
-131.3 b
-121.1 d

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
  b
  d

  b
  d

  b
  d

  b
  d
 
  b
  d
 
  b
  d

  b
  d

  b
  d

NC
NC

  b
  d

  b

  b
  d

  b
  d

NC
density functional LSDA
  b
  d

  b
  d

  b
  d

  b
  d

  b
  d

  b
  d

  b
  d

  b
  d

  b
  d

  b
  d
 
  b
  d

  b
  d

  b
  d
 
NC
NC
BLYP
  b
  d

  b
  d
 
  b
  d
 
  b
  d

  b
  d
 
  b
  d

  b
  d
 
  b
  d

  b
  d

NC
NC
 
NC
NC
B1B95
  b
  d

  b
  d

  b
  d

  b
  d

  b
  d

  b
  d

  b
  d

  b
  d

  b
  d

  b
  d
 
  b
  d

  b
  d

  b
  d
 
NC
NC
B3LYP
  b
  d

  b
  d

  b
  d

  b
  d

  b
  d

  b
  d

  b
  d

  b
  d

  b
  d

  b
  d

NC

  b
  d

  b
  d

  b
  d
 
NC
NC
B3LYPultrafine        
  b
  d
                     
B3PW91
  b
  d

  b
  d

  b
  d

  b
  d

  b
  d

  b
  d

  b
  d

  b
  d

  b
  d

  b
  d
 
  b
  d

  b
  d

NC
NC
 
NC
NC
mPW1PW91
  b
  d

  b
  d

  b
  d

  b
  d

  b
  d

  b
  d

  b
  d

  b
  d

  b
  d

  b
  d
 
  b
  d

  b
  d

  b
  d
 
NC
NC
PBEPBE
  b
  d

  b
  d

  b
  d

  b
  d

  b
  d

  b
  d

  b
  d

  b
  d

  b
  d

  b
  d

NC
NC

  b
  d

  b
  d

  b
  d
 
NC
NC
PBEPBEultrafine        
  b
  d
                     
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
Moller Plesset perturbation MP2
  b
  d

  b
  d

  b
  d

  b
  d
 
  b
  d
   
  b
  d

  b
  d
 
  b
  d
       
MP2=FULL        
  b
  d
   
  b
  d

  b
  d
             
MP3        
  b
  d
                     
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
Quadratic configuration interaction QCISD  
  d
                           
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

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

  b
  d

  b
  d

  b
  d

  b
  d

  b
  d
density functional B1B95
NC
NC

NC
NC
       
B3LYP
  b
  d

  b
  d

  b
  d

  b
  d

  b
  d

  b
  d
Moller Plesset perturbation MP2
  b
  d

  b
  d

  b
  d

  b
  d

  b
  d

  b
  d

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*
NC
NC

NC
NC
 
NC
NC
MP2FC// B3LYP/6-31G*
NC
NC
     
MP2FC// MP2FC/6-31G*    
NC
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.