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Geometry Comparison

C6H8 ((Z)-hexa-1,3,5-triene)


distance is atom 3 (C) to atom 5 (C)

Experimental bond length is 1.337  Å

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Calculated bond length in Å
Methods with predefined basis sets
semi-empirical PM3 1.331
PM6 1.335
composite G2 1.324
G3 1.324
G3B3 1.343
G4 1.338

Calculated bond length in Å
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) TZVP cc-pVDZ cc-pVTZ aug-cc-pVDZ aug-cc-pVTZ daug-cc-pVTZ
hartree fock HF 1.315 1.322 1.322 1.329 1.324 1.323 1.327 1.323 1.323 1.320 1.321 1.321 1.328   1.330 1.321 dnf
density functional LSDA 1.348 1.342 1.342 1.347 1.343 1.343 1.345 1.338 1.338 1.339     1.346 1.335 1.346    
BLYP 1.363 1.354   1.360 1.354 1.355 1.359   1.352 1.351     1.358 1.348 1.359    
B1B95 1.342 1.338 1.338 1.344 1.338 1.339 1.341 1.336 1.336 1.335     1.341 1.331 dnf    
B3LYP 1.347 1.341 1.341 1.348 1.343 1.343 1.346 1.340   1.339 1.337 1.338 1.346 1.336   1.336  
B3LYPultrafine         1.343                 1.336   1.336  
B3PW91   1.342 1.342 1.347 1.342 1.342   1.339   1.339     1.344 1.336 1.345    
mPW1PW91   1.339   1.344 1.340 1.339 1.342 1.336 1.336 1.336     1.342   1.343    
M06-2X     1.337   1.337           1.331            
PBEPBE   1.353     1.354 1.353 1.356 1.350 1.350 1.350 1.347   1.355 1.347      
PBEPBEultrafine         1.354                        
PBE1PBE         1.340                        
HSEh1PBE   1.340     1.340   1.343             1.334      
TPSSh         1.346   1.348     1.342       1.338      
wB97X-D     1.336   1.337   1.339   1.333     1.331 1.339 1.330   1.330  
B97D3   1.350     1.351   1.352   1.346   1.343 1.346   1.343   1.346 1.346
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) TZVP cc-pVDZ cc-pVTZ aug-cc-pVDZ aug-cc-pVTZ daug-cc-pVTZ
Moller Plesset perturbation MP2   1.351 1.350 1.360 1.346 1.346 1.349 1.347 1.348 1.343   1.342 1.356 1.343      
MP2=FULL         1.345     1.347                  
MP3         1.341   1.341                    
MP3=FULL         1.341   1.343                    
B2PLYP         1.344                 1.337      
B2PLYP=FULLultrafine         dnf               1.348 1.337   1.338  
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) TZVP cc-pVDZ cc-pVTZ aug-cc-pVDZ aug-cc-pVTZ daug-cc-pVTZ
Quadratic configuration interaction QCISD   1.345                              
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) TZVP cc-pVDZ cc-pVTZ aug-cc-pVDZ aug-cc-pVTZ daug-cc-pVTZ

Calculated bond length in Å
Methods with effective core potentials (select basis sets)
CEP-31G CEP-31G* CEP-121G CEP-121G* LANL2DZ SDD cc-pVTZ-PP aug-cc-pVTZ-PP Def2TZVPP
hartree fock HF 1.355 1.349 1.343 1.332 1.338 1.338     1.320
density functional B1B95 1.372 1.367              
B3LYP 1.375 1.369 1.362 1.352 1.358 1.358     1.336
PBEPBE                 1.345
Moller Plesset perturbation MP2 1.393 1.376 1.377 1.357 1.374 1.374     1.341
Values that are outliers may reflect incorrect atom numbering for different levels of theory.
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