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Comparison of experiment and theory for rKK

Species with coordinate rKK
Species Name
K2 Potassium dimer
The small prefix is the number of bonds with completed calculations.
Click on an entry for a histogram of the difference distribution.
rms differences (calculated - experiment) in Å
Methods with predefined basis sets
semi-empirical PM3 1 0.756
PM6 1 1.097
composite G2 1 0.258
G3 1 0.258
G3B3 1 0.116
CBS-Q 1 0.258

rms differences (calculated - experiment) 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
hartree fock HF 1 0.442 1 0.316 1 0.319 1 0.287 1 0.299 1 0.299 1 0.299 1 0.293 1 0.293 1 0.296 1 0.296 1 0.282  
density functional LSDA 1 0.500 1 0.997 1 0.997 1 0.092 1 0.075 1 0.075 1 0.075 1 0.083 1 0.083 1 0.081   1 0.066  
SVWN   1 0.045     1 0.075 1 0.075 1 0.075 1 0.083 1 0.083 1 0.081      
BLYP 1 0.398 1 0.102 1 0.079 1 0.073 2 0.117 1 0.091 1 0.091 1 0.087 1 0.087 1 0.090   1 0.101  
B1B95 1 0.466 1 0.081 1 0.081 1 0.048 1 0.065 1 0.065 1 0.065 1 0.069 1 0.069 1 0.067   1 0.070  
B3LYP 1 0.431 1 0.083 1 0.059 1 0.051 1 0.067 1 0.067 1 0.067 1 0.064 1 0.064 1 0.066   1 0.072  
B3LYPultrafine         1 0.065                
B3PW91 1 0.439 1 0.161 1 0.160 1 0.105 1 0.118 1 0.118 1 0.118 1 0.117 1 0.117 1 0.118   1 0.121  
mPW1PW91 1 0.447 1 0.163 1 0.160 1 0.107 1 0.121 1 0.121 1 0.121 1 0.120 1 0.120 1 0.120   1 0.122  
M06-2X 1 0.495 1 0.074 2 0.106 1 0.101 1 0.092 1 0.092 1 0.093 1 0.088 1 0.088 1 0.090   1 0.088  
PBEPBE 1 0.423 1 0.127 1 0.117 1 0.083 1 0.099 1 0.099 1 0.099 1 0.097 1 0.097 1 0.098   1 0.106  
PBEPBEultrafine         1 0.097                
PBE1PBE 1 0.449 1 0.135 1 0.135 1 0.094 1 0.108 1 0.108 1 0.108 1 0.107 1 0.107 1 0.107   1 0.108  
HSEh1PBE 1 0.448 1 0.146 1 0.140 1 0.101 1 0.112 1 0.112 1 0.112 1 0.109 1 0.109 1 0.111   1 0.115  
TPSSh         1 0.186   1 0.186     1 0.187      
wB97X-D     1 0.148   1 0.101   1 0.101   1 0.098     1 0.099 1 0.101
B97D3   1 0.207     1 0.181       1 0.182        
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
Moller Plesset perturbation MP2 1 0.421 1 0.321 1 0.299 1 0.294 2 0.168 1 0.161 1 0.158 2 0.065 1 0.014 1 0.096   1 0.279  
MP2=FULL 1 0.435 1 0.316 1 0.251 1 0.294 1 0.161 1 0.161 1 0.158 1 0.009 1 0.009 1 0.095   1 0.241  
MP3         1 0.152   1 0.170            
MP3=FULL         1 0.170   1 0.168            
MP4   1 0.312     1 0.160       1 0.040     1 0.262  
MP4=FULL   1 0.307     1 0.160       1 0.036        
Configuration interaction CID   1 0.314 1 0.281 1 0.294 1 0.161     1 0.093          
CISD   1 0.338 1 0.287 1 0.318 1 0.174     1 0.093          
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
Quadratic configuration interaction QCISD   1 0.338 1 0.288 1 0.320 1 0.191 1 0.191 1 0.188 1 0.083 1 0.083 1 0.138   1 0.287  
QCISD(T)         1 0.205     1 0.090       1 0.286  
Coupled Cluster CCD   1 0.315 1 0.281 1 0.295 1 0.164 1 0.164 1 0.161 1 0.060 1 0.060 1 0.127   1 0.258  
CCSD         1 0.192     1 0.083       1 0.287  
CCSD=FULL         1 0.192             1 0.261  
CCSD(T)         1 0.206     1 0.092       1 0.286  
CCSD(T)=FULL         1 0.206             1 0.265  
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

rms differences (calculated - experiment) in Å
Methods with effective core potentials (select basis sets)
CEP-31G CEP-31G* CEP-121G CEP-121G* LANL2DZ SDD
hartree fock HF 1 0.473   1 0.473   1 0.290 1 0.290
density functional B3LYP 1 0.419   1 0.419   1 0.070 1 0.063
Moller Plesset perturbation MP2 1 0.520   1 0.520   1 0.308 1 0.286
For descriptions of the methods (AM1, HF, MP2, ...) and basis sets (3-21G, 3-21G*, 6-31G, ...) see the glossary in section I.C. Predefined means the basis set used is determined by the method.