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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
semi-empirical PM3 2.028

Calculated bond length in Å
Methods with standard basis sets
3-21G 3-21G* 6-31G* 6-31+G** 6-311G* 6-311G** cc-pVTZ
hartree fock HF 2.194 2.178     2.160 2.159  
density functional BLYP 2.241 2.220     2.203 2.204  
B1B95 2.185 2.168     2.147 2.147  
B3LYP 2.213 2.193     2.175 2.174  
B3PW91 2.193 2.176     2.156 2.156  
mPW1PW91 2.187 2.170     2.150 2.150  
M06-2X   2.169          
PBEPBE 2.208 2.189     2.170 2.170  
wB97X-D   2.173          
B97D3 2.225     dnf     dnf
3-21G 3-21G* 6-31G* 6-31+G** 6-311G* 6-311G** cc-pVTZ
Moller Plesset perturbation MP2 2.204 2.199 2.162   2.151 2.145  
MP2=FULL 2.203 2.198     2.151 2.146  
Configuration interaction CID 2.206 2.195     2.150 2.144  
CISD 2.210 2.197     2.152 2.147  
3-21G 3-21G* 6-31G* 6-31+G** 6-311G* 6-311G** cc-pVTZ
Quadratic configuration interaction QCISD 2.219 2.207     2.162 2.157  
QCISD(T) 2.222 2.213     2.168 2.162  
Coupled Cluster CCD 2.212 2.204     2.157 2.151  
CCSD(T) 2.222 2.212     2.168 2.162  
3-21G 3-21G* 6-31G* 6-31+G** 6-311G* 6-311G** cc-pVTZ

Calculated bond length 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 2.180   2.176   2.180 2.186 2.145   2.139
ROHF             2.145   2.139
density functional LSDA             2.122   2.115
BLYP             2.192   2.185
B1B95 2.177   2.172   dnf 2.183 2.135   2.128
B3LYP 2.202   2.222   2.192 2.202 2.164   2.157
B3LYPultrafine             2.164   2.157
B3PW91             2.145   2.138
mPW1PW91             2.139   2.132
M06-2X             2.137   2.131
PBEPBE             2.160   2.153
PBEPBEultrafine             2.160   2.153
PBE1PBE             2.136   2.129
HSEh1PBE             2.140   2.133
TPSSh             2.155   2.148
wB97X-D             2.138   2.131
B97D3             2.177   2.168
Moller Plesset perturbation MP2 2.197   2.192   2.194 2.200 2.125   2.116
MP2=FULL             2.121   2.109
ROMP2             2.124   2.116
MP3             2.132   2.126
MP3=FULL             2.129   2.120
MP4             2.139   2.131
MP4=FULL             2.136   2.125
B2PLYP             2.150   2.143
B2PLYP=FULL             2.149   2.141
B2PLYP=FULLultrafine             2.149   2.141
Configuration interaction CID             2.125   2.114
CISD             2.127   2.115
Quadratic configuration interaction QCISD             2.136   2.128
QCISD(T)             2.141   2.134
QCISD(T)=FULL             2.137   2.128
Coupled Cluster CCD             2.132   2.124
CCSD             2.135   2.128
CCSD=FULL             2.131   2.121
CCSD(T)             2.140   2.134
CCSD(T)=FULL             2.137   2.127
Values that are outliers may reflect incorrect atom numbering for different levels of theory.
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