return to home page

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

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

Isomers of CHO2

index Species CAS number Name Relative experimental enthalpy (kJ mol-1) sketch
a HOCO 2564865 Hydrocarboxyl radical   sketch of Hydrocarboxyl radical
b HCOO 9000392 formate neutral radical   sketch of formate neutral radical
The calculated enthalpies include the calculated and scaled vibrational zero-point energy.
Methods with predefined basis sets
semi-empirical AM1
-108.9 b
PM3
-129.4 b
PM6 -117.2 a
-75.8 b
composite G1 NC
NC
G2MP2 NC
NC
G2 NC
NC
G3 NC
NC
G3B3 NC
NC
G3MP2 NC
G4 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) cc-pVDZ cc-pVTZ cc-pVQZ aug-cc-pVDZ aug-cc-pVTZ cc-pV(T+d)Z cc-pCVDZ
hartree fock HF   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  
B1B95   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  
B3LYPultrafine         NC                        
B3PW91   NC NC NC NC NC NC NC     NC NC       NC  
mPW1PW91   NC NC NC NC NC NC NC     NC NC       NC  
PBEPBE   NC NC NC NC NC NC NC     NC NC   NC   NC  
PBEPBEultrafine         NC                        
Moller Plesset perturbation MP2   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
MP3         NC                        
MP4         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     NC NC NC NC     NC NC   NC   NC  
Coupled Cluster CCD   NC NC NC NC NC NC NC     NC NC       NC  
CCSD   NC     NC NC NC NC     NC            
CCSD(T)   NC     NC NC NC NC     NC NC   NC   NC  
CCSD(T)=FULL         NC                        

Methods with effective core potentials (select basis sets)
CEP-31G CEP-31G* CEP-121G CEP-121G* LANL2DZ SDD
hartree fock HF -97850.6 a   -97866.7 a   NC NC
density functional B3LYP -99863.6 a   -99878.7 a   NC NC
Moller Plesset perturbation MP2 -98615.7 a   -98724.5 a   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 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.