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

Geometry Comparison

CN (Cyano radical)


distance is atom 1 (C) to atom 2 (N)

Experimental bond length is 1.172  Å

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Calculated bond length in Å
Methods with predefined basis sets
semi-empirical PM3 1.247
composite G2 1.162
G3 1.162
G3B3 1.174
G4 1.169
CBS-Q 1.161

Calculated bond length 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) 6-311+G(3df,2p) TZVP cc-pVDZ cc-pVTZ cc-pVQZ aug-cc-pVDZ aug-cc-pVTZ aug-cc-pVQZ cc-pCVDZ cc-pCVTZ
hartree fock HF 1.235 1.180 1.180 1.193 1.162 1.162 1.161 1.154 1.154 1.155 1.149 1.151 1.162 1.150 1.148 1.162 1.150 1.148 1.161 1.149
ROHF   1.145 1.145 1.151 1.137 1.137 1.137 1.131   1.133     1.139 1.129            
density functional LSDA 1.219 1.184 1.184 1.190 1.178 1.178 1.178 1.168 1.168 1.174     1.179 1.166   1.178        
BLYP 1.230 1.194 1.194 1.200 1.187 1.187 1.187 1.178 1.178 1.183     1.188 1.175   1.187        
B1B95 1.211 1.180 1.180 1.185 1.170 1.172 1.172 1.164 1.164 1.168     1.173 1.160   1.170        
B3LYP 1.215 1.182 1.182 1.188 1.174 1.174 1.174 1.166   1.169 1.162 1.163 1.175 1.163 1.161 1.174 1.162 1.161    
B3LYPultrafine         1.174                       1.162      
B3PW91   1.182 1.182 1.186 1.173 1.173 1.173 1.165   1.169     1.174 1.162   1.173        
mPW1PW91   1.179   1.183 1.170 1.170 1.169 1.162 1.162 1.166     1.171 1.160   1.170        
M06-2X         1.163                              
PBEPBE   1.194     1.185 1.185 1.185 1.178 1.178 1.181 1.174   1.187 1.175     1.175      
PBEPBEultrafine         1.185                              
PBE1PBE         1.171                              
TPSSh         1.178   1.178             1.169            
Moller Plesset perturbation MP2   1.141 1.141 1.147 1.115 1.135 1.136 1.130 1.130 1.129   1.114 1.139 1.102 1.123 1.139 1.126 1.123 1.138 1.125
MP2=FULL   1.141     1.114 1.135 1.135 1.129         1.138 1.099 1.121 1.138 1.123   1.137 1.124
MP3         1.139   1.127                          
MP3=FULL         1.126   1.127                          
MP4         1.147     1.141                        
B2PLYP                           1.175            
Configuration interaction CID         1.141     1.135                        
CISD         1.156                              
Quadratic configuration interaction QCISD   1.195     1.181   1.181 1.175 1.175       1.185 1.168            
QCISD(T)         1.190     1.184                        
Coupled Cluster CCD         1.141     1.135         1.144              
CCSD         1.181     1.174                        
CCSD(T)   1.198     1.186 1.186 1.186 1.180 1.180   1.173   1.190 1.174   1.191 1.174   1.189 1.173
CCSD(T)=FULL         1.185               1.190 1.171   1.190 1.169   1.189 1.171

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 1.217 1.184 1.211 1.166 1.206 1.206
density functional B1B95 1.205 1.192        
B3LYP 1.209 1.194 1.202 1.179 1.199 1.199
Moller Plesset perturbation MP2 1.168 1.151 1.156 1.139 1.154 1.154
Values that are outliers may reflect incorrect atom numbering for different levels of theory.
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