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

Geometry Comparison

NaK (Sodium Potassium)


distance is atom 1 (Na) to atom 2 (K)

Experimental bond length is 3.589  Å

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Calculated bond length in Å
Methods with predefined basis sets
semi-empirical PM6 3.847
composite G2 3.650
G3 3.652
G3B3 3.547
G4 3.584
CBS-Q 3.650

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
hartree fock HF 2.849 3.707 3.715 3.685 3.688 3.688 3.692 3.690 3.690 3.688 3.702
density functional LSDA 2.799 2.885 2.885 3.401 3.405   3.404 3.394 3.394 3.386 3.431
SVWN   3.421     3.405 3.405 3.404 3.394 3.394 3.386  
BLYP 2.851 3.509 3.479 3.520 3.531 3.531 3.531 3.517 3.517 3.515 3.546
B1B95 2.825 3.549 3.549 3.510 3.513 3.513 3.513 3.516 3.516 3.508 3.540
B3LYP 2.836 3.501 3.474 3.504 3.511 3.511 3.511 3.502 3.502 3.500 3.527
B3LYPultrafine         3.510            
B3PW91 2.842 3.592 3.596 3.559 3.560 3.560 3.560 3.555 3.555 3.553 3.581
mPW1PW91 2.838 3.589 3.592 3.560 3.561 3.561 3.561 3.557 3.557 3.555 3.581
M06-2X 2.809 3.461 3.430 3.391 3.389 3.389 3.389 3.389   3.387 3.414
PBEPBE 2.844 3.544 3.537 3.537 3.541 3.541 3.541 3.534 3.534 3.531 3.562
HSEh1PBE 2.833 3.563 3.561 3.551 3.552 3.552 3.552 3.546 3.546 3.545 3.572
TPSSh         3.609   3.609        
Moller Plesset perturbation MP2 2.847 3.706 3.697 3.680 3.570 3.570 3.574 3.532 3.532 3.444 3.704
MP2=FULL 2.831 3.701 3.668 3.678 3.557 3.557 3.560 3.503 3.503 3.415 3.673
MP3         3.554   3.576        
MP3=FULL         3.569   3.571        
MP4   3.695     3.555       3.534    
Configuration interaction CID   3.694 3.681 3.673 3.560     3.549      
CISD   3.708 3.686 3.687 3.567     3.549      
Quadratic configuration interaction QCISD   3.708 3.686 3.688 3.572 3.572 3.577 3.558 3.558 3.451 3.708
QCISD(T)         3.572           3.708
Coupled Cluster CCD   3.694 3.680 3.673 3.560 3.560 3.564 3.544 3.544 3.459 3.689
CCSD         3.571            
CCSD(T)         3.572           3.708
CCSD(T)=FULL         3.559           3.689

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 3.743   3.699   3.713 3.683
density functional B3LYP 3.707   3.668   3.589 3.508
Moller Plesset perturbation MP2 3.780   3.720   3.726 3.671
Values that are outliers may reflect incorrect atom numbering for different levels of theory.
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