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

Geometry Comparison

CH3CH(NH2)COOH (Alanine)


distance is atom 2 (C) to atom 3 (C)

Experimental bond length is 1.509  Å

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Calculated bond length in Å
Methods with predefined basis sets
semi-empirical AM1 1.527
PM3 1.522
composite G2 1.526
G3 1.526
G3B3 1.530
G4 1.532
CBS-Q 1.528

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 aug-cc-pVDZ aug-cc-pVTZ
hartree fock HF   1.531 1.531 1.530 1.526 1.526 1.527 1.525 1.525 1.526 1.524 1.524 1.524 1.523 1.526  
density functional LSDA 1.530 1.508 1.508 1.510 1.507 1.506 1.509 1.503 1.504 1.506     1.506 1.502 1.510  
SVWN   1.515     1.507   1.513                  
BLYP   1.543 1.543 1.545 1.541 1.540 1.543 1.539 1.540 1.540     1.539 1.538 1.542  
B1B95   1.524 1.524 1.525 1.520 1.520 1.522 1.518 1.519 1.520     1.518 1.517 1.520  
B3LYP   1.533 1.533 1.534 1.530 1.529 1.531 1.528 1.529 1.529   1.529 1.528 1.526 1.530  
B3LYPultrafine         1.530                 1.528   1.528
B3PW91   1.527 1.527 1.529 1.525 1.524 1.526 1.522 1.523 1.524     1.523 1.521 1.525  
mPW1PW91   1.525 1.525 1.526 1.522 1.522 1.523 1.520 1.520 1.522     1.520 1.518 1.522  
M06-2X         1.525                      
PBEPBE   1.533 1.533 1.534 1.530 1.530 1.532 1.528 1.529 0.975     1.528 1.527 1.531  
PBEPBEultrafine         1.535                      
PBE1PBE         1.521                      
TPSSh         1.533   1.533             1.528    
Moller Plesset perturbation MP2   1.539 1.539 1.543 1.523 1.521 1.524 1.523 1.524 1.522   1.521 1.526 1.519 1.531  
MP2=FULL   1.539 1.539 1.542 1.521 1.520 1.522 1.521 1.522 1.517     1.525 1.513    
MP3         1.525   1.525                  
MP3=FULL         1.525   1.524                  
B2PLYP         1.528                 1.521    
B2PLYP=FULLultrafine         1.528                      
Configuration interaction CID   1.535 1.535 1.537 1.520     1.520 1.521              
CISD   1.536 1.536 1.537 1.520     1.520 1.521              
Quadratic configuration interaction QCISD   1.544     1.526               1.531      
Coupled Cluster CCD   1.543     1.526               1.530      

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 1.547   1.543   1.539 1.539
density functional B1B95 1.544 1.537        
B3LYP 1.554   1.550   1.542 1.543
Moller Plesset perturbation MP2 1.568   1.561   1.560 1.560
Values that are outliers may reflect incorrect atom numbering for different levels of theory.
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