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IV.D.1. (XII.C.1.)

Geometry Comparison

C6H8 (1,3,5-Hexatriene, (Z)-)


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
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
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  
SVWN   1.342     1.343   1.345                  
BLYP 1.363 1.354   1.360 1.356 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    
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                      
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                      
TPSSh         1.346   1.348             1.338    
Moller Plesset perturbation MP2   1.351 1.350 1.360 1.346 1.346 1.349 1.348 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         1.343                      
Quadratic configuration interaction QCISD   1.345                            

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