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Comparison of experiment and theory for rII

18 10 23 14 56
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
M06-2X   1 0.012    
PBEPBE 1 0.235 1 0.040   1 0.061
wB97X-D   1 0.007    
B97D3 1 0.248      
3-21G 3-21G* 6-31G* 6-311G*
Moller Plesset perturbation MP2 1 0.252 1 0.045 1 0.071 1 0.071
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 cc-pVTZ-PP aug-cc-pVTZ-PP Def2TZVPP
hartree fock HF 1 0.105   1 0.105   1 0.152 1 0.140 1 0.003   1 0.003
ROHF             1 0.003   1 0.003
density functional LSDA             1 0.015   1 0.024
BLYP             1 0.074   1 0.066
B1B95             1 0.005   1 0.012
B3LYP 1 0.158   1 0.158   1 0.197 1 0.187 1 0.038   1 0.030
B3LYPultrafine             1 0.038   1 0.030
B3PW91             1 0.009   1 0.001
mPW1PW91             1 0.000   1 0.007
M06-2X             1 0.007   1 0.013
PBEPBE             1 0.028   1 0.021
PBEPBEultrafine             1 0.028   1 0.021
PBE1PBE             1 0.002   1 0.010
HSEh1PBE             1 0.006   1 0.002
TPSSh             1 0.012   1 0.005
wB97X-D             1 0.004   1 0.003
B97D3             1 0.051   1 0.043
Moller Plesset perturbation MP2 1 0.170   1 0.170   1 0.211 1 0.202 1 0.008   1 0.021
MP2=FULL             1 0.008   1 0.024
ROMP2             1 0.008   1 0.021
MP3             1 0.013   1 0.010
MP3=FULL             1 0.013   1 0.008
MP4             1 0.017   1 0.008
MP4=FULL             1 0.017   1 0.005
B2PLYP             1 0.019   1 0.011
B2PLYP=FULL             1 0.019   1 0.010
B2PLYP=FULLultrafine             1 0.019   1 0.010
Configuration interaction CID             1 0.003   1 0.021
CISD             1 0.002   1 0.020
Quadratic configuration interaction QCISD             1 0.013   1 0.005
QCISD(T)             1 0.022   1 0.016
QCISD(T)=FULL             1 0.021   1 0.013
Coupled Cluster CCD             1 0.011   1 0.001
CCSD             1 0.013   1 0.005
CCSD=FULL             1 0.012   1 0.002
CCSD(T)             1 0.022   1 0.016
CCSD(T)=FULL             1 0.021   1 0.013
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.