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IV.D.1. (XII.C.1.)

Geometry Comparison

CH3I (methyl iodide)


distance is atom 1 () to atom 2 ()

Experimental bond length is 2.136  Å

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Calculated bond length in Å
Methods with predefined basis sets

Calculated bond length in Å
Methods with standard basis sets
3-21G 3-21G* 6-311G* 6-311G**
hartree fock HF 2.194 2.178 2.160  
density functional BLYP 2.241 2.220 2.203  
B1B95 2.185 2.168 2.147  
B3LYP 2.213 2.193 2.175  
B3PW91 2.193 2.176 2.156  
mPW1PW91 2.187 2.170 2.150  
PBEPBE 2.208 2.189 2.170  
Moller Plesset perturbation MP2 2.204 2.199 2.150  
MP2=FULL 2.203 2.198 2.151  
Configuration interaction CID 2.206 2.195 2.150  
CISD 2.210 2.197 2.152  
Quadratic configuration interaction QCISD 2.219 2.207 2.162 2.157
QCISD(T) 2.222 2.213 2.168  
Coupled Cluster CCD 2.212 2.204 2.157  
CCSD(T) 2.222 2.212 2.168 2.162

Calculated bond length in Å
Methods with effective core potentials (select basis sets)
CEP-31G CEP-31G* CEP-121G CEP-121G* LANL2DZ SDD
hartree fock HF 2.180   2.176   2.180 2.186
density functional B1B95 2.177   2.172   dnf 2.183
B3LYP 2.202   2.222   2.192 2.202
Moller Plesset perturbation MP2 2.197   2.192   2.194 2.200
Values that are outliers may reflect incorrect atom numbering for different levels of theory.
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