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

Geometry Comparison

SiF2 (Silicon difluoride)


distance is atom 1 (Si) to atom 2 (F)

Experimental bond length is 1.590  Å

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Calculated bond length in Å
Methods with predefined basis sets
semi-empirical PM6 1.593
composite G2 1.592
G3 1.592
G3B3 1.610
G4 1.602
CBS-Q 1.599

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) TZVP cc-pVDZ cc-pVTZ cc-pVQZ aug-cc-pVDZ aug-cc-pVTZ aug-cc-pVQZ
hartree fock HF 1.602 1.625 1.587 1.676 1.593 1.592 1.602 1.594 1.594 1.579 1.598 1.634 1.584 1.576 1.621 1.583 1.576
ROHF   1.625 1.587 1.676 1.592 1.592 1.602 1.594 1.594     1.634 1.584 1.576 1.621 1.583 1.576
density functional LSDA 1.646 1.597 1.597 1.699 1.609 1.609 1.627 1.616 1.616 1.593   1.648 1.610   1.650 1.611  
BLYP 1.666 1.671 1.620 1.723 1.633 1.633 1.656 1.644 1.644 1.618   1.671 1.638        
B1B95 1.636 1.598 1.598 1.695 1.609 1.609 1.625 1.615 1.615 1.596   1.648 1.609   1.646 1.610  
B3LYP 1.644 1.652 1.604 1.703 1.616 1.616 1.635 1.624 1.624 1.602 1.634 1.655 1.618 1.610 1.656 1.619 1.610
B3LYPultrafine         1.616                     1.607  
B3PW91 1.644 1.653 1.605 1.702 1.615 1.615 1.631 1.621 1.621 1.601   1.654 1.614        
mPW1PW91 1.639 1.648 1.601 1.698 1.611 1.611 1.627 1.617 1.617 1.597   1.651 1.610   1.648 1.611  
M06-2X 1.630 1.637 1.594 1.691 1.607 1.607 1.622 1.613 1.613 1.595   1.646 1.606   1.642 1.607  
PBEPBE 1.664 1.670 1.618 1.720 1.630 1.630 1.650 1.638 1.638 1.616   1.669 1.632   1.672 1.634  
HSEh1PBE 1.639 1.649 1.602 1.699 1.612 1.612 1.628 1.618 1.618 1.598   1.651 1.611   1.649 1.612  
TPSSh         1.614   1.620           1.609        
Moller Plesset perturbation MP2 1.618 1.644 1.600 1.704 1.611 1.617 1.637 1.615 1.615 1.601 1.629 1.655 1.606 1.604 1.658 1.615 1.605
MP2=FULL 1.618 1.644 1.599 1.704 1.611 1.616 1.635 1.615 1.615 1.596   1.654 1.604 1.597 1.657 1.610 1.597
MP3         1.610   1.608                    
MP3=FULL         1.607   1.612                    
MP4   1.650     1.621       1.618       1.613        
Configuration interaction CID   1.637 1.594 1.694 1.607     1.603                  
CISD   1.639 1.596 1.696 1.608     1.604                  
Quadratic configuration interaction QCISD   1.645 1.601 1.705 1.617 1.617 1.634 1.612 1.612 1.599   1.655 1.605   1.654 1.608  
QCISD(T)         1.618             1.657 1.609        
Coupled Cluster CCD   1.640 1.597 1.699 1.613 1.613 1.628 1.608 1.608 1.595   1.650 1.602   1.648 1.604  
CCSD         1.614             1.653 1.604        
CCSD(T)         1.617             1.656 1.608 1.600 1.656 1.612 1.601
CCSD(T)=FULL         1.616               1.606   1.655 1.607  

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 1.700 1.605 1.699 1.605 1.663 1.678
density functional B3LYP 1.728 1.633 1.729 1.636 1.691 1.705
Moller Plesset perturbation MP2 1.743 1.639 1.740 1.641 1.701 1.714
Values that are outliers may reflect incorrect atom numbering for different levels of theory.
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