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

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

Isomers of CH4O3

index Species CAS number Name Relative experimental enthalpy (kJ mol-1) sketch
a HCOOHH2O 99 Formic acid water dimer   sketch of Formic acid water dimer
b H2OHCOOH 102 Water formic acid dimer 1   sketch of Water formic acid dimer 1
c H2OHCOOH 113 Water formic acid dimer 2   sketch of Water formic acid dimer 2
d HOCH2OOH 15932895 hydroxy methyl peroxide   sketch of hydroxy methyl peroxide
The calculated enthalpies include the calculated and scaled vibrational zero-point energy.
Methods with predefined basis sets
semi-empirical PM3 -470.6 a
-485.1 b
-486.2 c
composite G1
NC
NC
G2MP2
NC
NC
G2
NC
NC
G3B3 NC
NC
NC
NC
G3MP2 NC
NC
NC
G4 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) 6-311+G(3df,2pd) cc-pVDZ cc-pVTZ 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
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
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
B3LYP   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
 
PBEPBE   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
 
Moller Plesset perturbation MP2   NC
NC
NC
    NC
NC
NC
  NC
NC
NC
        NC
NC
NC
         
Coupled Cluster CCSD(T)   NC
NC
    NC
NC
  NC                    

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

NC
 
density functional B1B95 NC
NC
NC
NC
NC
       
B3LYP      
NC

NC
 
Moller Plesset perturbation MP2      
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
  NC
NC
NC
  NC
NC
NC
MP2FC// B3LYP/6-31G* NC NC
NC
NC
NC
NC
NC
  NC
NC
NC
MP2FC// MP2FC/6-31G*     NC
NC
NC
NC
NC
NC
NC
NC
NC
MP4// HF/6-31G* NC
NC
NC
  NC
NC
NC
  NC
NC
NC
MP4// B3LYP/6-31G*   NC
NC
NC
NC
NC
NC
  NC
NC
NC
MP4// MP2/6-31G*     NC
NC
NC
  NC
NC
NC
Coupled Cluster CCSD// B3LYP/6-31G* NC        
CCSD(T)// B3LYP/6-31G* NC        
CCSD// MP2FC/6-31G*       NC
NC
NC
 
CCSD(T)// MP2FC/6-31G*       NC
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.