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Geometry Comparison

C2H2O2 (Ethanedial)


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

Experimental bond length is 1.526  Å

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Calculated bond length in Å
Methods with predefined basis sets
semi-empirical AM1 1.503
PM3 1.526
PM6 1.543
composite G2 1.517
G3 1.517
G3B3 1.525
G3MP2 1.517
G4 1.529
CBS-Q 1.521

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 daug-cc-pVDZ daug-cc-pVTZ
hartree fock HF 1.541 1.503 1.503 1.494 1.517 1.517 1.518 1.520 1.520 1.520 1.520 1.522 1.516 1.519 1.520 1.520 1.520 1.521 1.521 1.520
ROHF   1.503 1.503 1.494 1.517 1.517 1.519 1.520 1.520   1.520 1.522 1.516 1.519 1.520 1.520 1.520 1.521 1.521 1.520
density functional LSDA   1.502 1.502     1.508 1.508   1.509 1.507     1.508 1.505   1.508        
BLYP 1.597 1.535 1.535 1.520 1.537 1.537 1.538 1.541 1.541 1.538 1.537 1.539 1.539 1.536   1.539 1.536   1.539 1.536
B1B95 1.559 1.511 1.511 1.499 1.518 1.518 1.518 1.518 1.519 1.518 1.517 1.519 1.517 1.516   1.518 1.517   1.518 1.517
B3LYP 1.573 1.518 1.518 1.507 1.525 1.525 1.526 1.527 1.527 1.526 1.525 1.526 1.525 1.523 1.525 1.527 1.524 1.525 1.527 1.524
B3LYPultrafine   1.518     1.525 1.525 1.526 1.527   1.526 1.525 1.526 1.525 1.523   1.527 1.524   1.527 1.524
B3PW91 1.566 1.516 1.516 1.504 1.522 1.522 1.523 1.524 1.524 1.523 1.522 1.524 1.522 1.521   1.523 1.522   1.523 1.522
mPW1PW91 1.561 1.512 1.513 1.500 1.519 1.519 1.520 1.520 1.521 1.522 1.519 1.521 1.518 1.517   1.520 1.519   1.521 1.519
M06-2X 1.560 1.520 1.520 1.505 1.523 1.524 1.524 1.525 1.525 1.523 1.523 1.525 1.523 1.521   1.525 1.523   1.525 1.523
PBEPBE 1.580 1.527 1.527 1.513 1.530 1.530 1.530 1.532 1.532 1.531 1.529 1.531 1.530 1.528   1.530 1.529   1.531 1.529
PBEPBEultrafine   1.527     1.530 1.530 1.530 1.532   1.531 1.529 1.531 1.530 1.528   1.530 1.529   1.531 1.529
PBE1PBE 1.558 1.512 1.512 1.500 1.519 1.519 1.520 1.520 1.520 1.520 1.519 1.521 1.518 1.518   1.520 1.519   1.520 1.519
HSEh1PBE 1.559 1.511 1.511 1.499 1.519 1.519 1.519 1.520 1.520 1.520 1.519 1.520 1.518 1.517   1.519 1.518   1.520 1.518
TPSSh 1.570 1.519 1.519 1.506 1.526 1.523 1.527 1.525 1.525 1.525 1.523 1.525 1.523 1.522 1.523 1.524 1.523 1.523 1.525 1.523
wB97X-D 1.568 1.517 1.517 1.507 1.525 1.525 1.525 1.526 1.526 1.526 1.525 1.527 1.525 1.523 1.525 1.526 1.524 1.525 1.526 1.525
B97D3 1.586 1.531 1.531 1.516 1.534 1.534 1.534 1.536 1.536 1.536 1.534 1.535 1.534 1.532 1.534 1.535 1.533 1.534 1.535 1.533
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 daug-cc-pVDZ daug-cc-pVTZ
Moller Plesset perturbation MP2 1.572 1.521 1.521 1.510 1.514 1.514 1.515 1.521 1.522 1.516 1.516 1.517 1.523 1.514 1.513 1.524 1.515 1.514 1.524 1.515
MP2=FULL 1.572 1.521 1.521 1.510 1.513 1.512 1.513 1.519 1.520 1.511 1.511 1.516 1.521 1.507 1.508 1.522 1.508 1.508 1.522 1.508
ROMP2 1.572 1.521 1.521 1.510 1.514 1.513 1.514 1.521 1.522 1.517 1.516 1.517 1.523 1.514   1.523     1.524 1.516
MP3         1.515   1.516                          
MP3=FULL         1.516   1.517                          
MP4         1.523                              
B2PLYP 1.571 1.517 1.517 1.506 1.519 1.518 1.520 1.523 1.524 1.521 1.520 1.522 1.523 1.519   1.523 1.520   1.524 1.520
B2PLYP=FULL 1.571 1.517 1.517 1.506 1.520 1.518 1.520 1.523 1.523 1.520 1.519 1.521 1.522 1.516   1.523 1.517   1.523 1.518
B2PLYP=FULLultrafine 1.571 1.517 1.517 1.506 1.519 1.518 1.520 1.523 1.523 1.520 1.519 1.521 1.522 1.516   1.523 1.517   1.523 1.518
Configuration interaction CID   1.516 1.516 1.507 1.514     1.519     1.515   1.520 1.512         1.522 1.513
CISD   1.518 1.518 1.508 1.515     1.520     1.515   1.521 1.513         1.523 1.514
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 daug-cc-pVDZ daug-cc-pVTZ
Quadratic configuration interaction QCISD   1.529 1.529 1.519 1.523 1.521 1.522 1.528 1.530 1.524 1.524 1.525 1.531 1.521   1.532 1.522   1.532 1.522
QCISD(T)         1.521     1.529     1.523 1.525 1.531 1.521   1.532 1.522   1.532 dnf
QCISD(T)=FULL         1.519           1.519       1.515 1.530 1.514 1.515    
Coupled Cluster CCD   1.522 1.522 1.514 1.518 1.517 1.519 1.525 1.526 1.520 1.521 1.521 1.527 1.518   1.529 1.519   1.529 1.519
CCSD         1.519 1.519 1.520 1.527 1.528 1.522 1.522 1.523 1.528 1.519 1.518 1.530 1.520 dnf 1.530 1.520
CCSD=FULL         1.518         1.516 1.517 1.522 1.527 1.511 dnf 1.528 1.513 dnf 1.528 1.513
CCSD(T)         1.519 1.519 1.520 1.528 1.529 1.523 1.523 1.524 1.530 1.520 1.519 1.531 1.521 1.520 1.531 1.521
CCSD(T)=FULL         1.518           1.518 1.523 1.528 1.512 1.514 1.530 1.513 1.514 1.530 1.514
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 daug-cc-pVDZ 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 1.524 1.537 1.517 1.533 1.508 1.508     1.520
ROHF                 1.520
density functional BLYP                 1.536
B1B95 1.537 1.546             1.517
B3LYP 1.543 1.551 1.531 1.543 1.523 1.523     1.524
B3LYPultrafine                 1.524
B3PW91                 1.522
mPW1PW91                 1.519
M06-2X                 1.523
PBEPBE                 1.529
PBEPBEultrafine                 1.529
PBE1PBE                 1.519
HSEh1PBE                 1.518
TPSSh                 1.523
wB97X-D 1.541 1.549 1.528 1.540 1.523 1.523     1.525
B97D3                 1.533
Moller Plesset perturbation MP2 1.552 1.543 1.537 1.534 1.534 1.534     1.515
MP2=FULL                 1.513
ROMP2                 1.515
B2PLYP                 1.520
B2PLYP=FULL                 1.519
B2PLYP=FULLultrafine                 1.519
Configuration interaction CID                 1.514
CISD                 1.514
Quadratic configuration interaction QCISD                 1.522
QCISD(T)                 1.522
Coupled Cluster CCD                 1.519
CCSD                 1.520
CCSD=FULL                 1.519
CCSD(T)                 1.521
CCSD(T)=FULL                 1.520
Values that are outliers may reflect incorrect atom numbering for different levels of theory.
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