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

Geometry Comparison

B2 (Boron diatomic)


distance is atom 1 (B) to atom 2 (B)

Experimental bond length is 1.590  Å

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Calculated bond length in Å
Methods with predefined basis sets
semi-empirical AM1 1.306
PM3 1.454
PM6 1.489
composite G2 1.476
G3 1.476
G3B3 1.510
G4 1.508
CBS-Q 1.480

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 cc-pVQZ aug-cc-pVDZ aug-cc-pVTZ aug-cc-pVQZ cc-pCVDZ cc-pCVTZ
hartree fock HF 1.447 1.515 1.515 1.516 1.341 1.506 1.508 1.504 1.504 1.504 1.636 1.502 1.515 1.503 1.501 1.515 1.503 1.501 1.649 1.636
ROHF 1.447 1.515 1.515 1.516 1.506 1.506 1.508 1.504 1.504 1.503   1.632 1.515 1.503 1.635 1.515 1.502 1.635    
density functional LSDA 1.489 1.535 1.535 1.537 1.529 1.529 1.530 1.520 1.520 1.526   1.521 1.538 1.519   1.536 1.519      
SVWN   1.535     1.529 1.529 1.530 1.520 1.520 1.526     1.538 1.519   1.536 1.519      
BLYP 1.499 1.543 1.543 1.544 1.537 1.537 1.538 1.530 1.530 1.534   1.530 1.544 1.528            
B1B95 1.478 1.529 1.529 1.531 1.522 1.522 1.523 1.517 1.517 1.520   1.516 1.530 1.515 1.514 1.529 1.515 1.514 1.629 1.616
B3LYP 1.484 1.531 1.531 1.533 1.524 1.524 1.525 1.518 1.518 1.521   1.518 1.532 1.516 1.515 1.531 1.516 1.514 1.628 1.612
B3LYPultrafine   1.531     1.524 1.524 1.525 1.518       1.518 1.532 1.516   1.531 1.516      
B3PW91 1.482 1.533 1.533 1.534 1.526 1.526 1.527 1.520 1.520 1.523   1.520 1.533 1.518            
mPW1PW91 1.479 1.531 1.531 1.532 1.523 1.523 1.524 1.518 1.518 1.521   1.518 1.530 1.517   1.530 1.516      
M06-2X 1.476 1.527 1.527 1.529 1.520 1.520 1.521 1.515 1.515 1.517   1.513 1.528 1.514   1.527 1.513      
PBEPBE 1.496 1.545 1.545 1.546 1.538 1.538 1.539 1.532 1.532 1.536   1.532 1.545 1.531 1.529 1.544 1.530 1.529    
PBEPBEultrafine   1.545     1.538 1.538 1.539 1.532       1.532 1.545 1.531   1.544 1.530      
PBE1PBE 1.479 1.532 1.532 1.533 1.525 1.525 1.526 1.520 1.520 1.522   1.519 1.532 1.518   1.531 1.518      
HSEh1PBE 1.479 1.532 1.532 1.533 1.525 1.525 1.526 1.519 1.519 1.522   1.519 1.532 1.518   1.531 1.518      
TPSSh   1.542 1.542 1.543 1.499 1.534 1.499 1.529       1.528 1.541 1.495   1.540 1.527      
Moller Plesset perturbation MP2 1.483 1.542 1.542 1.545 1.523 1.523 1.525 1.528 1.528 1.521   1.521 1.544 1.521 1.516 1.545 1.521 1.516 1.619 1.597
MP2=FULL 1.483 1.542 1.542 1.545 1.521 1.521 1.523 1.526 1.526 1.516   1.519 1.543 1.513 1.509 1.543 1.512 1.509 1.617 1.593
ROMP2 1.483 1.542 1.542 1.545 1.523 1.523 1.526 1.528 1.528 1.522   1.598 1.545 1.522   1.545        
MP3         1.524   1.499         1.523 1.548 1.523            
MP3=FULL         1.499   1.499         1.521 1.547 1.514            
MP4   1.550     1.529       1.535     1.527 1.552 1.527   1.553 1.527      
MP4=FULL   1.550     1.526       1.534       1.551 1.518   1.551 1.516      
B2PLYP 1.481 1.534 1.534 1.536 1.523 1.523 1.525 1.521 1.521 1.521   1.519 1.536 1.490   1.535 1.518      
B2PLYP=FULL 1.481 1.534 1.534 1.536 1.522 1.522 1.524 1.521 1.521 1.519   1.518 1.535 1.515   1.535 1.515      
Configuration interaction CID   1.545 1.545 1.548 1.522     1.527                        
CISD   1.547 1.547 1.551 1.525     1.530                        
Quadratic configuration interaction QCISD   1.550 1.550 1.554 1.527 1.527 1.529 1.533 1.533 1.525   1.525 1.550 1.524   1.550 1.524      
QCISD(T)         1.531             1.529 1.554 1.529   1.555 1.529      
QCISD(T)=FULL         1.529   1.530           1.553 1.520 1.517 1.553 1.518 1.516    
QCISD(TQ)         1.624   1.630           1.660 1.631 1.624 1.663 1.631 1.624    
QCISD(TQ)=FULL         1.529   1.531           1.554 1.521 1.517 1.555 1.519 1.517    
Coupled Cluster CCD   1.547 1.547 1.551 1.523 1.523 1.525 1.529 1.529 1.521   1.521 1.546 1.521   1.547 1.520   1.628 1.602
CCSD         1.526             1.524 1.549 1.523 1.518 1.549 1.523 1.518    
CCSD=FULL         1.524             1.523 1.548 1.514 1.511 1.548 1.513 1.511    
CCSD(T)         1.530           1.488 1.529 1.554 1.529 1.523 1.554 1.528 1.523 1.626 1.598
CCSD(T)=FULL         1.528             1.527 1.553 1.519 1.516 1.553 1.518 1.516 1.624 1.594

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 1.562 1.553 1.529 1.513 1.530 1.529
density functional B1B95 1.683 1.664        
B3LYP 1.585 1.576 1.551 1.535 1.550 1.551
Moller Plesset perturbation MP2 1.602 1.576 1.562 1.531 1.565 1.564
Values that are outliers may reflect incorrect atom numbering for different levels of theory.
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