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Comparison of experiment and theory for rII

Species with coordinate rII
Species Name
I2 Iodine diatomic
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 AM1 1 0.127
PM3 1 0.003

rms differences (calculated - experiment) in Å
Methods with standard basis sets
3-21G 3-21G* 6-31G* 6-311G*
hartree fock HF 1 0.199 1 0.031   1 0.037
density functional BLYP 1 0.273 1 0.084   1 0.109
B1B95       1 0.028
B3LYP 1 0.237 1 0.053   1 0.071
B3PW91 1 0.212 1 0.026   1 0.041
mPW1PW91 1 0.203 1 0.018   1 0.032
PBEPBE 1 0.235 1 0.040   1 0.061
wB97X-D   1 0.007    
B97D3 1 0.229      
3-21G 3-21G* 6-31G* 6-311G*
Moller Plesset perturbation MP2 1 0.252 1 0.045 1 0.071 2 0.061
MP2=FULL 1 0.253 1 0.044   1 0.052
MP3       1 0.065
MP4 1 0.283     1 0.074
Configuration interaction CID 1 0.272 1 0.049   1 0.047
CISD 1 0.276 1 0.050   1 0.047
3-21G 3-21G* 6-31G* 6-311G*
Quadratic configuration interaction QCISD 1 0.289 1 0.062   1 0.068
QCISD(T)       1 0.078
Coupled Cluster CCD 1 0.283 1 0.060   1 0.065
CCSD(T)       1 0.078
CCSD(T)=FULL       1 0.081
3-21G 3-21G* 6-31G* 6-311G*

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 0.105   1 0.105   1 0.152 1 0.140
density functional B3LYP 1 0.158   1 0.158   1 0.197 1 0.187
Moller Plesset perturbation MP2 1 0.170   1 0.170   1 0.211 1 0.202
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.