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

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

Isomers of CH3O2

index Species CAS number Name Relative experimental enthalpy (kJ mol-1) sketch
a CH3OO 2143580 methylperoxy radical   sketch of methylperoxy radical
b CH2OOH 9000344 CH2OOH   sketch of CH2OOH
The calculated enthalpies include the calculated and scaled vibrational zero-point energy.
Methods with predefined basis sets
semi-empirical AM1 71.3 a
PM3 117.5 a
PM6 94.5 a
32.5 b
composite G1 NC
NC
G2MP2 NC
NC
G2 NC
NC
G3 NC
NC
G3B3 NC
NC
G3MP2 NC
G4 NC
NC
CBS-Q 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) cc-pVDZ cc-pVTZ cc-pVQZ aug-cc-pVDZ aug-cc-pVTZ cc-pV(T+d)Z
hartree fock HF 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
density functional LSDA 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
B1B95             NC                    
B3LYP NC NC NC NC NC NC NC NC NC NC   NC NC   NC NC NC
B3LYPultrafine         NC                        
B3PW91 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
PBEPBE NC NC NC NC NC NC NC NC NC NC   NC NC     NC NC
Moller Plesset perturbation MP2 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
MP4   NC     NC       NC                
Configuration interaction CID   NC NC NC NC     NC                  
CISD   NC NC NC NC     NC                  
Quadratic configuration interaction QCISD   NC NC NC NC NC NC NC NC NC   NC          
QCISD(T)         NC                        
Coupled Cluster CCD   NC NC NC NC NC NC NC NC NC   NC          
CCSD         NC                        
CCSD(T)         NC                        

Methods with effective core potentials (select basis sets)
CEP-31G CEP-31G* CEP-121G CEP-121G* LANL2DZ SDD
hartree fock HF NC NC NC NC NC NC
density functional B1B95 NC NC        
B3LYP NC NC NC NC NC NC
Moller Plesset perturbation MP2 NC NC NC NC NC NC

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* NC   NC   NC
MP2FC// B3LYP/6-31G* NC NC NC   NC
MP2FC// MP2FC/6-31G*     NC NC NC
MP4// HF/6-31G* NC   NC   NC
MP4// B3LYP/6-31G*   NC NC   NC
MP4// MP2/6-31G*     NC   NC
Coupled Cluster CCSD// B3LYP/6-31G* NC        
CCSD(T)// B3LYP/6-31G* NC        
CCSD(T)//B3LYP/6-31G(2df,p)     NC   NC
CCSD// MP2FC/6-31G*       NC  
CCSD(T)// MP2FC/6-31G*       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 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.