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

Geometry Comparison

C5H8 (Cyclobutane, methylene-)


distance is atom 1 (C) to atom 3 (C)

Experimental bond length is 1.524  Å

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Calculated bond length in Å
Methods with predefined basis sets
semi-empirical PM3 1.508
PM6 1.514
composite G3 1.084
G3B3 1.524
G4 1.524
CBS-Q 1.087

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 1.532 1.535 1.535 1.524 1.519 1.519 1.519 1.520 1.519 1.519 1.517 1.518 1.520 1.517 1.521 1.517
density functional LSDA 1.532 1.525 1.525 1.516 1.506 1.505 1.506 1.504 1.503 1.504     1.506 1.501 1.506  
SVWN   1.525     1.506   1.506                  
BLYP 1.562 1.555 1.555 1.545 1.535 1.535 1.536 1.535 1.534 1.534     1.535 1.531 1.535  
B1B95 1.537 1.533 1.533 1.523 1.512 1.513 1.514 1.512 1.512 1.512     1.513 1.509 1.512  
B3LYP 1.549 1.542 1.542 1.533 1.524 1.524 1.524 1.524   1.523 1.519 1.521 1.525 1.520 1.524  
B3LYPultrafine         1.524                     1.521
B3PW91   1.537 1.537 1.527 1.518 1.518 1.519 1.518   1.518     1.519 1.515 1.519  
mPW1PW91   1.535 1.535 1.525 1.516 1.516 1.516 1.515 1.515 1.515     1.516 1.512 1.516  
M06-2X         1.518                      
PBEPBE   1.546     1.525 1.524 1.525 1.524 1.524 1.523 1.521   1.525 1.520    
PBEPBEultrafine         1.525                      
PBE1PBE         1.516                      
HSEh1PBE         1.516                      
TPSSh         1.525   1.525             1.521    
Moller Plesset perturbation MP2   1.550 1.550 1.543 1.521 1.517 1.521 1.521 1.520 1.517   1.517 1.526 1.518 1.527  
MP2=FULL   1.550 1.550 1.543 1.519 1.515 1.516 1.519         1.524 1.511    
MP3         1.523   1.523                  
MP3=FULL         1.523   1.522                  
B2PLYP         1.521                 1.520    
B2PLYP=FULLultrafine         1.523                      
Configuration interaction CID   1.545     1.516                      
CISD   1.545     1.517                      
Quadratic configuration interaction QCISD   1.556 1.556 1.547 1.524 1.523 1.524 1.527         1.532      
Coupled Cluster CCD   1.554 1.554 1.546 1.523 1.522 1.523 1.526         1.531      

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 1.539 1.532 1.535 1.529 1.530 1.529
density functional B1B95 1.540 1.530        
B3LYP 1.551 1.541 1.546 1.537 1.537 1.537
Moller Plesset perturbation MP2 1.569 1.536 1.560 1.530 1.556 1.556
Values that are outliers may reflect incorrect atom numbering for different levels of theory.
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