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

Isomers of C7H16

index Species CAS number Name Relative experimental enthalpy (kJ mol-1) sketch
a C7H16 591764 2-methylhexane 0.0 sketch of 2-methylhexane
b C7H16 589344 3-methylhexane 2.7 sketch of 3-methylhexane
c C7H16 142825 heptane 7.2 sketch of heptane
The calculated enthalpies include the calculated and scaled vibrational zero-point energy.
Methods with predefined basis sets
semi-empirical AM1 0.0 a
554.7 b
-10.5 c
PM6 0.0 a
526.5 b
5.0 c
composite G1 0.0 a
614.1 b
7.5 c
G2MP2 0.0 a
614.2 b
7.4 c
G2 0.0 a
614.5 b
7.4 c
G3 0.0 a
614.2 b
6.9 c
G3B3 0.0 a
3.2 b
7.7 c
G3MP2 0.0 a
615.2 b
7.0 c
G4 0.0 a
4.9 b
8.0 c
CBS-Q 0.0 a

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 0.0 a
-3.1 c
0.0 a
2.1 c
0.0 a
2.1 c
0.0 a
-1.7 c
  0.0 a
-2.7 c
0.0 a 0.0 a
-2.7 c
0.0 a
-2.5 c
0.0 a
-3.0 c
0.0 a
-2.7 c
0.0 a
-2.9 c
0.0 a
-3.2 c
0.0 a
-2.7 c
0.0 a 0.0 a
-3.2 c
density functional LSDA 0.0 a
4.1 c
0.0 a
11.5 c
0.0 a
11.5 c
0.0 a
7.8 c
0.0 a
7.3 c
0.0 a
7.5 c
0.0 a
7.4 c
0.0 a
7.9 c
0.0 a
8.5 c
0.0 a
8.1 c
  0.0 a
7.5 c
0.0 a
7.7 c
0.0 a
8.8 c
  0.0 a
7.7 c
BLYP 0.0 a 0.0 a
1.8 c
0.0 a
1.8 c
0.0 a
-0.5 c
  0.0 a
-0.9 c
0.0 a
-1.1 c
0.0 a
-1.5 c
0.0 a
-1.0 c
0.0 a
-0.4 c
  0.0 a
-0.9 c

NC
   
NC
B1B95 0.0 a
8.1 c
0.0 a
6.2 c
0.0 a
6.2 c
0.0 a
-0.9 c
0.0 a
1.0 c
0.0 a
2.3 c
0.0 a
1.7 c
0.0 a
1.0 c
0.0 a
1.2 c

NC
  0.0 a
2.8 c
0.0 a
1.0 c

NC
  0.0 a
1.0 c
B3LYP 0.0 a
-1.1 c
0.0 a
2.9 c
0.0 a
2.9 c
0.0 a
-0.0 c
0.0 a
-0.6 c
0.0 a
-0.5 c
0.0 a
-0.5 c
0.0 a
-0.8 c
0.0 a
-0.3 c
0.0 a
-0.2 c
  0.0 a
-0.6 c
0.0 a
-0.8 c
0.0 a
0.1 c
  0.0 a
-0.8 c
B3LYPultrafine         0.0 a                      
B3PW91   0.0 a
3.6 c
0.0 a
3.6 c
0.0 a
0.0 c
0.0 a
-0.6 c
0.0 a
-0.4 c
0.0 a
-0.3 c
0.0 a
-0.3 c
0.0 a
0.1 c
0.0 a
-0.3 c
  0.0 a
-0.6 c
0.0 a
-0.7 c
    0.0 a
-0.7 c
mPW1PW91 0.0 a
-1.2 c
0.0 a
11.4 c
0.0 a
11.3 c
0.0 a
7.3 c
0.0 a
6.7 c
0.0 a
6.9 c
0.0 a
6.9 c
0.0 a
6.9 c
0.0 a
0.9 c
0.0 a
0.3 c
  0.0 a
6.9 c
0.0 a
6.5 c
    0.0 a
6.5 c
PBEPBE 0.0 a 0.0 a
5.0 c
0.0 a
5.0 c
0.0 a
1.6 c
0.0 a
1.1 c
0.0 a
1.3 c
0.0 a
1.3 c
0.0 a
1.1 c
0.0 a
1.6 c
0.0 a
1.5 c
  0.0 a
1.2 c
0.0 a
1.1 c
    0.0 a
1.1 c
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 0.0 a 0.0 a
8.1 c
0.0 a
8.1 c
0.0 a
5.3 c
  0.0 a
5.9 c
0.0 a   0.0 a
7.6 c
0.0 a
7.7 c
  0.0 a
6.6 c

NC
0.0 a
9.0 c
 
NC
MP2=FULL 0.0 a 0.0 a
8.2 c
0.0 a
8.2 c
0.0 a
5.5 c
0.0 a
6.1 c
0.0 a
6.2 c
0.0 a
7.2 c
0.0 a
7.7 c
0.0 a
7.9 c
0.0 a
10.3 c
  0.0 a
6.8 c
       
MP4  
NC
                           
Configuration interaction CID   0.0 a 0.0 a 0.0 a 0.0 a     0.0 a                
CISD   0.0 a 0.0 a 0.0 a 0.0 a     0.0 a                
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 0.0 a 0.0 a
6.6 c
0.0 a
6.6 c
0.0 a
3.7 c
0.0 a
3.4 c
0.0 a
3.3 c
 
NC
     
NC
       
Coupled Cluster CCD 0.0 a 0.0 a
6.4 c

NC

NC
0.0 a
3.1 c

NC
 
NC
               
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 0.0 a
-0.5 c
0.0 a
-0.7 c
0.0 a
-1.8 c
0.0 a
-2.2 c
0.0 a
-1.7 c
0.0 a
-1.6 c
density functional B1B95 0.0 a
3.1 c
0.0 a
3.2 c
       
B3LYP 0.0 a
1.6 c
0.0 a
1.9 c
0.0 a
0.2 c
0.0 a
0.2 c
0.0 a
0.8 c
0.0 a
0.7 c
Moller Plesset perturbation MP2 0.0 a
8.2 c
0.0 a
8.5 c
0.0 a
8.9 c
0.0 a
9.5 c
0.0 a
8.6 c
0.0 a
8.7 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 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.