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

Geometry Comparison

C6H8 (Bicyclo[2.1.1]hex-2-ene)


distance is atom 1 (C) to atom 4 (C)

Experimental bond length is 1.544  Å

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Calculated bond length in Å
Methods with predefined basis sets
semi-empirical PM3 1.530
PM6 1.462
composite G2 1.534
G3 1.534
G3B3 1.537
G4 1.539

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 1.545 1.547 1.547 1.538 1.534 1.534 1.533 1.534 1.534 1.534 1.531 1.456 1.535 1.531 1.535 1.531
density functional LSDA 1.545 1.536 1.536 1.530 1.521 1.521 1.520 1.520 1.520 1.520     1.522 1.517 1.521  
SVWN   1.451     1.521   1.450                  
BLYP 1.574 1.562   1.556 1.547 1.548 1.547   1.547 1.547     1.549 1.543 1.548  
B1B95 1.548 1.542 1.542 1.535 1.526 1.527 1.526 1.526 1.526 1.526     1.526 1.522 1.525  
B3LYP 1.562 1.551 1.551 1.545 1.537 1.537 1.537 1.537   1.536 1.533 1.454 1.538 1.533    
B3LYPultrafine         1.537                     1.535
B3PW91   1.547 1.547 1.540 1.532 1.532   1.531   1.532     1.533 1.528 1.532  
mPW1PW91   1.544   1.538 1.530 1.530 1.529 1.529 1.529 1.530     1.530   1.530  
M06-2X         1.455                      
PBEPBE   1.554     1.538 1.538 1.538 1.537 1.538 1.538 1.534   1.539 1.534    
PBEPBEultrafine         1.538                      
PBE1PBE         1.530                      
HSEh1PBE         1.454                      
TPSSh         1.537   1.537             1.534    
Moller Plesset perturbation MP2   1.557 1.557 1.551 1.527 1.526 1.529 1.529 1.530     1.454 1.534      
MP2=FULL         1.525     1.528                
MP3         1.535   1.536                  
MP3=FULL         1.535   1.534                  
B2PLYP         1.455                 1.530    
B2PLYP=FULLultrafine         1.535                      

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 1.547 1.540 1.547 1.540 1.542 1.542
density functional B1B95 1.548 1.538        
B3LYP 1.557 1.547 1.556 1.546 1.548 1.548
Moller Plesset perturbation MP2 1.572 1.540 1.564 1.535 1.563 1.563
Values that are outliers may reflect incorrect atom numbering for different levels of theory.
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