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Geometry Comparison

C8H8 (cyclooctatetraene)


distance is atom 1 (C) to atom 2 (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 1.335
PM6 1.339
composite G3 1.324
G3B3 1.342
G4 1.337

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 1.316 1.320 1.320 1.329 1.324 1.323 1.326 1.322 1.322 1.320 1.320 1.320 1.327 1.320 1.328 1.320 1.320
density functional LSDA 1.347 1.339 1.339 1.346 1.342 1.342 1.344 1.337 1.337 1.338     1.345 1.334 1.345    
BLYP 1.362 1.351 1.351 1.359 1.349 1.354 1.357 1.350         1.357 1.346 1.357    
B1B95 1.341 1.335 1.335 1.343 1.337 1.338 1.340 1.335 1.335 1.334     1.340 1.330 1.339    
B3LYP 1.347 1.339 1.339 1.347 1.342 1.342 1.345 1.338   1.338   1.337 1.345 1.335 1.345 1.331  
B3LYPultrafine                               1.334  
B3PW91   1.339 1.339 1.346 1.341 1.341 1.343 1.338         1.344 1.334 1.344    
mPW1PW91   1.336 1.336 1.343 1.339 1.339 1.341 1.335 1.335       1.341 1.332      
M06-2X     1.335   1.337           1.331            
PBEPBE                 1.348 1.348 1.346            
PBE1PBE         1.340                        
HSEh1PBE   1.337     1.340   1.342             1.333      
TPSSh         1.342   1.343     1.337       1.334      
wB97X-D     1.333   1.336   1.337   1.331     1.329 1.337 1.327   1.328  
B97D3   1.343     1.345   1.347   1.340   1.337 1.343   1.337   1.343 1.343
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   1.350 1.350 1.361 1.344 1.347 1.351 1.344 1.349     1.344 1.357        
MP2=FULL   1.349 1.349 1.361 1.346 1.346 1.349 1.348         1.356        
MP3             1.340                    
MP3=FULL         1.339   1.342                    
B2PLYP         1.344                 1.334      
B2PLYP=FULLultrafine         1.343               1.348 1.337   1.337  
Configuration interaction CID   1.331     1.329                        
CISD   1.332     1.329                        
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 1.342 1.331 1.338 1.337     1.318
density functional B1B95 1.371 1.367              
B3LYP 1.374 1.368 1.361 1.351 1.356 1.357     1.332
PBEPBE                 1.340
Moller Plesset perturbation MP2 1.396 1.377 1.378 1.358 1.376 1.375     1.338
Values that are outliers may reflect incorrect atom numbering for different levels of theory.
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