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

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

Isomers of C2H2F2

index Species CAS number Name Relative experimental enthalpy (kJ mol-1) sketch
a C2H2F2 1630779 Ethene, 1,2-difluoro-, (Z)-   sketch of Ethene, 1,2-difluoro-, (Z)-
b C2H2F2 1630780 Ethene, 1,2-difluoro-, (E)-   sketch of Ethene, 1,2-difluoro-, (E)-
c CH2CF2 75387 Ethene, 1,1-difluoro- 0.0 sketch of Ethene, 1,1-difluoro-
The calculated enthalpies include the calculated and scaled vibrational zero-point energy.
Methods with predefined basis sets
semi-empirical AM1 102.8 a
102.1 b
0.0 c
PM3 26.4 a
32.2 b
0.0 c
PM6 35.8 a
31.7 b
0.0 c
MNDOd
0.0 c
composite G1 44.7 a
-60.1 b
0.0 c
G2MP2 44.2 a
-60.5 b
0.0 c
G2 45.1 a
-60.1 b
0.0 c
G3 45.9 a
-59.5 b
0.0 c
G3B3 41.8 a
44.3 b
0.0 c
G3MP2 45.1 a
-59.9 b
0.0 c
G4 41.4 a
44.4 b
0.0 c
CBS-Q 44.9 a
45.3 b
0.0 c
molecular mechanics MM3
0.0 c

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 40.9 a
0.0 c
55.6 a
0.0 c
55.6 a
0.0 c
33.7 a
0.0 c
  50.1 a
0.0 c
  48.3 a
0.0 c
47.3 a
0.0 c
53.5 a
0.0 c
42.6 a
46.4 b
0.0 c
49.3 a
0.0 c
46.0 a
0.0 c
38.3 a
0.0 c
41.9 a
0.0 c
46.0 a
0.0 c
density functional LSDA 49.6 a
49.8 b
0.0 c
62.5 a
60.5 b
0.0 c
62.5 a
60.5 b
0.0 c
46.4 a
44.6 b
0.0 c
56.6 a
56.9 b
0.0 c
56.3 a
56.7 b
0.0 c
45.0 a
48.0 b
0.0 c
55.0 a
55.6 b
0.0 c
54.5 a
55.0 b
0.0 c
58.3 a
59.7 b
0.0 c
  56.4 a
56.2 b
0.0 c
51.1 a
53.4 b
0.0 c
44.0 a
48.4 b
0.0 c
  51.1 a
53.4 b
0.0 c
BLYP 44.0 a
0.0 c
51.5 a
0.0 c
51.5 a
0.0 c
36.6 a
0.0 c
45.6 a
0.0 c
45.3 a
0.0 c
34.2 a
0.0 c
44.1 a
0.0 c
43.5 a
0.0 c
47.6 a
0.0 c
  45.2 a
44.7 b
0.0 c
40.5 a
0.0 c

0.0 c
  40.5 a
0.0 c
B1B95 44.0 a
0.0 c
55.9 a
0.0 c
55.9 a
0.0 c
38.7 a
0.0 c
39.9 a
0.0 c
50.8 a
0.0 c
40.1 a
0.0 c
48.9 a
0.0 c
48.4 a
0.0 c

0.0 c
  50.4 a
0.0 c
33.4 a
0.0 c

0.0 c
  33.4 a
0.0 c
B3LYP 43.1 a
0.0 c
53.7 a
0.0 c
53.7 a
0.0 c
36.8 a
0.0 c
48.0 a
0.0 c
47.6 a
0.0 c
36.4 a
0.0 c
46.0 a
0.0 c
45.4 a
0.0 c
50.1 a
0.0 c

0.0 c
47.3 a
0.0 c
42.7 a
0.0 c
35.4 a
0.0 c
-59.0 a
0.0 c
42.7 a
0.0 c
B3LYPultrafine         48.1 a
0.0 c
                     
B3PW91 44.2 a
0.0 c
55.8 a
0.0 c
55.8 a
0.0 c
38.6 a
0.0 c
50.7 a
0.0 c
50.2 a
0.0 c
39.5 a
0.0 c
48.3 a
0.0 c
47.7 a
0.0 c
52.1 a
0.0 c
  49.6 a
0.0 c
45.2 a
0.0 c

0.0 c
  45.2 a
0.0 c
mPW1PW91 44.1 a
0.0 c
52.0 a
0.0 c
56.4 a
0.0 c
38.8 a
0.0 c
47.4 a
0.0 c
46.9 a
0.0 c
36.2 a
0.0 c
45.0 a
0.0 c
48.4 a
0.0 c
52.9 a
0.0 c
  46.2 a
0.0 c
42.1 a
0.0 c

0.0 c
  42.1 a
0.0 c
PBEPBE 46.3 a
0.0 c
55.3 a
0.0 c
55.3 a
0.0 c
40.3 a
0.0 c
50.2 a
0.0 c
49.9 a
0.0 c
39.1 a
0.0 c
48.3 a
0.0 c
47.7 a
0.0 c
51.4 a
0.0 c

0.0 c
NC 44.9 a
0.0 c

0.0 c

0.0 c
44.9 a
0.0 c
Moller Plesset perturbation MP2 40.5 a
0.0 c
58.0 a
0.0 c
58.0 a
0.0 c
37.1 a
0.0 c
  51.8 a
0.0 c
  52.9 a
0.0 c
51.5 a
0.0 c
58.2 a
0.0 c
  54.0 a
0.0 c
  39.6 a
0.0 c
 
0.0 c
MP2=FULL NC 58.0 a
0.0 c
NC NC   52.5 a
0.0 c
39.9 a
0.0 c
53.3 a
0.0 c
51.8 a
0.0 c
NC   54.2 a
0.0 c
      NC
MP3         1625.3 a
0.0 c
                     
MP4   NC     48.1 a
0.0 c
                     
Configuration interaction CID   NC NC NC 49.8 a
0.0 c
    NC                
CISD   NC NC NC NC     NC                
Quadratic configuration interaction QCISD NC 52.8 a
0.0 c
NC NC 47.2 a
0.0 c
46.5 a
0.0 c
35.1 a
0.0 c
48.2 a
0.0 c
46.2 a
0.0 c
NC   NC NC     NC
QCISD(T)         NC       NC              
Coupled Cluster CCD NC NC NC NC 47.6 a
0.0 c
NC   a NC NC NC     a   a     NC
CCSD                 NC              
CCSD(T)         47.8 a
0.0 c
      NC              

Methods with effective core potentials (select basis sets)
CEP-31G CEP-31G* CEP-121G CEP-121G* LANL2DZ SDD
hartree fock HF 17.5 a
0.0 c
37.0 a
0.0 c
21.2 a
0.0 c
40.1 a
0.0 c
24.5 a
0.0 c
24.8 a
0.0 c
density functional B1B95 26.7 a
24.5 b
0.0 c
41.6 a
42.7 b
0.0 c
       
B3LYP 23.6 a
0.0 c
37.4 a
0.0 c
24.0 a
0.0 c
37.6 a
0.0 c
29.7 a
0.0 c
30.0 a
0.0 c
Moller Plesset perturbation MP2 21.0 a
0.0 c
40.0 a
0.0 c
23.3 a
0.0 c
41.4 a
0.0 c
27.6 a
0.0 c
27.8 a
0.0 c

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*
0.0 c

0.0 c

0.0 c

0.0 c

0.0 c
MP2FC// B3LYP/6-31G*
0.0 c

0.0 c

0.0 c

0.0 c

0.0 c
MP2FC// MP2FC/6-31G*  
0.0 c

0.0 c

0.0 c

0.0 c
MP4// HF/6-31G*
0.0 c

0.0 c

0.0 c
 
0.0 c
MP4// B3LYP/6-31G*  
0.0 c

0.0 c
 
0.0 c
MP4// MP2/6-31G*    
0.0 c
 
0.0 c
Coupled Cluster CCSD// HF/6-31G*  
0.0 c

0.0 c
 
0.0 c
CCSD(T)// HF/6-31G*  
0.0 c

0.0 c
 
0.0 c
CCSD// B3LYP/6-31G*
0.0 c

0.0 c
     
CCSD(T)// B3LYP/6-31G*
0.0 c

0.0 c
     
CCSD(T)//B3LYP/6-31G(2df,p)     44.6 a
0.0 c
  44.6 a
0.0 c
CCSD// MP2FC/6-31G*  
0.0 c

0.0 c

0.0 c

0.0 c
CCSD(T)// MP2FC/6-31G*  
0.0 c

0.0 c

0.0 c

0.0 c
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.