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Comparison of experiment and theory for rHeHe

Species with coordinate rHeHe
Species Name
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 PM6 1 0.538
composite G2 1 0.054
G3 1 0.054
G3B3 1 0.140
G4 1 0.068

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) TZVP cc-pVDZ cc-pVTZ cc-pVQZ aug-cc-pVTZ
hartree fock HF 1 0.078 1 0.072 1 0.072 1 0.054 2 0.054 1 0.002 1 0.002 1 0.028 1 0.001 1 0.002 1 0.006 1 0.005 1 0.006 1 0.005  
ROHF 1 0.078 1 0.061 1 0.061 1 0.034 1 0.034 1 0.016 1 0.016 1 0.006 1 0.016 1 0.016   1 0.018 1 0.020 1 0.020  
density functional LSDA 1 0.189 1 0.173 1 0.173 1 0.165 1 0.165 1 0.080 1 0.080 1 0.135 1 0.082 1 0.080   1 0.078 1 0.077 1 0.078  
SVWN   1 0.173     1 0.164   1 0.080       1 0.077        
BLYP 1 0.234 1 0.194 1 0.194 1 0.190 2 0.145 1 0.104 1 0.104 1 0.166 1 0.109 1 0.104   1 0.102 1 0.103    
B1B95 1 0.181 1 0.153 1 0.153 1 0.138 1 0.138 1 0.065 1 0.065 1 0.111 1 0.068 1 0.065   1 0.063 1 0.063 1 0.064  
B3LYP 1 0.180 1 0.152 1 0.152 1 0.140 1 0.140 1 0.066 1 0.066 1 0.115 1 0.070 1 0.066 1 0.064 1 0.064 1 0.064 1 0.065 1 0.078
B3LYPultrafine         1 0.140                   1 0.067
B3PW91 1 0.181 1 0.154 1 0.154 1 0.139 1 0.139 1 0.060 1 0.060 1 0.110 1 0.064 1 0.060   1 0.058 1 0.059    
mPW1PW91 1 0.168 1 0.144 1 0.144 1 0.128 1 0.128 1 0.050 1 0.050 1 0.099 1 0.055 1 0.050   1 0.048 1 0.050    
M06-2X     1 0.078   1 0.106                    
PBEPBE 1 0.228 1 0.195 1 0.195 1 0.188 1 0.188 1 0.095 1 0.095 1 0.162 1 0.101 1 0.095   1 0.093 1 0.095 1 0.095  
PBE1PBE         1 0.128                    
HSEh1PBE   1 0.145     1 0.128   1 0.053           1 0.051    
TPSSh         1 0.078   1 0.075     1 0.075     1 0.074    
wB97X-D     1 0.078   1 0.078   1 0.078   1 0.078   1 0.078 1 0.078 1 0.078   1 0.078
B97D3   1 0.078     1 0.078       1 0.078           1 0.078
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-pVTZ
Moller Plesset perturbation MP2   1 0.084 1 0.084 1 0.071 2 0.074 1 0.001 1 0.001 2 0.063 1 0.005 1 0.001 1 0.004 1 0.003 1 0.009 1 0.009  
MP2=FULL   1 0.084 1 0.084 1 0.071 1 0.071 1 0.001 1 0.001 1 0.042 1 0.005 1 0.001   1 0.003 1 0.009 1 0.009  
ROMP2 1 0.079 1 0.085 1 0.085 1 0.073 1 0.073 1 0.002 1 0.002 1 0.044 1 0.006 1 0.002   1 0.002 1 0.007 1 0.007  
MP3         1 0.077   1 0.048                
MP3=FULL         1 0.078   1 0.048                
MP4   1 0.089     1 0.080       1 0.013       1 0.003    
B2PLYP         1 0.100               1 0.064    
Configuration interaction CID   1 0.088 1 0.088 1 0.081 1 0.081     1 0.054              
CISD   1 0.089 1 0.089 1 0.082 1 0.082     1 0.057              
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-pVTZ
Quadratic configuration interaction QCISD   1 0.089 1 0.089 1 0.082 1 0.082 1 0.009 1 0.009 1 0.057 1 0.016 1 0.009   1 0.005 1 0.001    
QCISD(T)         1 0.083             1 0.004 1 0.001    
Coupled Cluster CCD   1 0.088 1 0.088 1 0.081 1 0.081 1 0.008 1 0.008 1 0.054 1 0.014 1 0.008   1 0.003 1 0.003    
CCSD(T)         1 0.083             1 0.004 1 0.001 1 0.001  
CCSD(T)=FULL         1 0.079                 1 0.001  
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-pVTZ

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 0.028 1 0.028   1 0.054
density functional B3LYP     1 0.115 1 0.115   1 0.140
Moller Plesset perturbation MP2     1 0.042 1 0.042   1 0.071
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.