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Geometry Comparison

CaOH (Calcium monohydroxide)


distance is atom 1 (Ca) to atom 2 (O)

Experimental bond length is 1.976  Å

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Calculated bond length in Å
Methods with predefined basis sets
semi-empirical PM6 2.026
composite G2 2.070
G3B3 1.942
G4 1.948

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
hartree fock HF 2.041 2.048 2.037 2.087 2.070 2.069 2.101 2.006 2.008 2.037   2.127    
density functional BLYP 2.090 2.098 2.058 2.118 2.090 2.084 2.120 1.973 1.975 2.035        
B3LYP     2.043 2.096 2.069 2.068 2.105 1.971 1.972 2.025   2.138    
B3PW91 2.067 2.063 2.037 2.091 2.065 2.065 2.099 1.964 1.966 2.018        
mPW1PW91 2.062 2.057 2.033 2.086 2.061 2.061 2.095 1.963 1.965 2.016        
M06-2X     2.038   2.062           1.984      
PBEPBE 2.085 2.085 2.048 2.108 2.074 2.074 2.110 1.961 1.962 2.024        
PBE1PBE         2.060                  
HSEh1PBE   2.058     2.060   2.095             1.959
TPSSh         2.064   2.110     2.001       1.944
wB97X-D     2.021   2.062   2.114   1.947     2.153 2.114 1.956
B97D3   2.223     2.088   2.124   1.949   1.956 2.156   1.950
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
Moller Plesset perturbation MP2 2.052 2.085 2.074 2.103 2.078 2.074 2.119 1.968 1.998 2.023   2.177    
MP2=FULL 2.048 2.069 2.051 2.103 2.074 2.074 2.118 1.994 1.997 2.022        
MP3             2.071              
MP3=FULL         2.072   2.124              
MP4 2.086 2.098     2.078       2.001 2.024        
B2PLYP         2.069                 1.991
B2PLYP=FULLultrafine         2.070               1.982 1.981
Configuration interaction CID   2.077     2.070       2.000 2.021        
CISD   2.082     2.072       2.000 2.021        
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
Quadratic configuration interaction QCISD 2.078 2.092   2.105 2.075 2.075 2.114 2.000 2.003 2.023        
QCISD(T)   2.095 2.081 2.105 2.076   2.116 1.998 2.001          
Coupled Cluster CCD 2.045 2.079   2.099 2.072 2.071 2.111 1.998 2.001 2.021        
CCSD   2.085 2.075 2.102 2.074   2.113 1.999 2.002 2.022        
CCSD(T)     2.080 2.105 2.076   2.075 1.998 2.001 2.022        
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

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 1.979   1.973   2.097 2.006     1.998
density functional B3LYP 1.981   1.983   2.096 1.961     1.965
PBEPBE                 1.957
Moller Plesset perturbation MP2 2.000   1.999   2.112 2.011     2.133
Values that are outliers may reflect incorrect atom numbering for different levels of theory.
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