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Geometry Comparison

HI (Hydrogen iodide)


distance is atom 1 () to atom 2 ()

Experimental bond length is 1.609  Å

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Calculated bond length in Å
Methods with predefined basis sets
semi-empirical PM3 1.677

Calculated bond length in Å
Methods with standard basis sets
3-21G 3-21G* 6-31G* 6-31+G** 6-311G* 6-311G**
hartree fock HF 1.638 1.631     1.624 1.609
density functional BLYP 1.677 1.660     1.654 1.639
B1B95 1.653 1.639     1.632 1.618
B3LYP 1.662 1.647     1.641 1.626
B3PW91 1.657 1.642     1.637 1.623
mPW1PW91 1.654 1.640     1.634 1.620
M06-2X   1.637        
PBEPBE 1.671 1.654     1.649 1.634
wB97X-D   1.637        
B97D3 1.666     dnf    
3-21G 3-21G* 6-31G* 6-31+G** 6-311G* 6-311G**
Moller Plesset perturbation MP2 1.657 1.645 1.642   1.647 1.606
MP2=FULL 1.657 1.645     1.638 1.607
Configuration interaction CID 1.670 1.651     1.640 1.607
CISD 1.672 1.652     1.641 1.607
3-21G 3-21G* 6-31G* 6-31+G** 6-311G* 6-311G**
Quadratic configuration interaction QCISD 1.674 1.656     1.648 1.612
QCISD(T) 1.674 1.658     1.651 1.613
Coupled Cluster CCD 1.672 1.655     1.647 1.611
CCSD(T) 1.674 1.658     1.651 1.613
3-21G 3-21G* 6-31G* 6-31+G** 6-311G* 6-311G**

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 1.616   1.613   1.615 1.617 1.603   1.597
ROHF             1.603   1.597
density functional LSDA             1.625   1.619
BLYP             1.635   1.629
B1B95 1.641   1.639   1.638 1.641 1.613   1.607
B3LYP 1.640   1.638   1.636 1.639 1.621   1.616
B3LYPultrafine             1.621   1.616
B3PW91             1.618   1.612
mPW1PW91             1.615   1.609
M06-2X             1.612   1.606
PBEPBE             1.630   1.625
PBEPBEultrafine             1.630   1.625
PBE1PBE             1.616   1.610
HSEh1PBE             1.618   1.612
TPSSh             1.619   1.613
wB97X-D             1.614   1.609
B97D3             1.626   1.620
Moller Plesset perturbation MP2 1.637   1.634   1.633 1.637 1.601   1.590
MP2=FULL             1.598   1.586
ROMP2             1.601   1.591
MP3             1.605   1.596
MP3=FULL             1.602   1.592
MP4             1.608   1.600
MP4=FULL             1.606   1.595
B2PLYP             1.613   1.606
B2PLYP=FULL             1.612   1.604
B2PLYP=FULLultrafine             1.612   1.604
Configuration interaction CID             1.602   1.589
CISD             1.603   1.590
Quadratic configuration interaction QCISD             1.608   1.599
QCISD(T)             1.610   1.602
QCISD(T)=FULL             1.608   1.597
Coupled Cluster CCD             1.607   1.597
CCSD             1.608   1.599
CCSD=FULL             1.605   1.594
CCSD(T)             1.610   1.602
CCSD(T)=FULL             1.608   1.597
Values that are outliers may reflect incorrect atom numbering for different levels of theory.
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