return to home page

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

Geometry Comparison

HNCO (Isocyanic acid)


distance is atom 3 (C) to atom 4 (O)

Experimental bond length is 1.164  Å

Display Options
Switch to bar chart display
Calculated bond length in Å
Methods with predefined basis sets
semi-empirical PM3 1.181
PM6 1.175
composite G2 1.148
G3 1.148
G3B3 1.174
G4 1.164
CBS-Q 1.143

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
hartree fock HF 1.183 1.178 1.178 1.180 1.148 1.148 1.148 1.139 1.139 1.140 1.137 1.139 1.144 1.139 1.137 1.144 1.139
density functional LSDA 1.226 1.196 1.196 1.200 1.177 1.177 1.177 1.168 1.167 1.170     1.175 1.167   1.175  
SVWN   1.196     1.177   1.177                    
BLYP 1.240 1.207 1.207 1.213 1.188 1.188 1.189 1.179 1.179 1.181     1.186 1.178   1.185  
B1B95 1.218 1.192 1.192 1.196 1.169 1.171 1.171 1.162 1.162 1.164     1.168 1.159   1.166  
B3LYP 1.223 1.195 1.195 1.200 1.174 1.174 1.175 1.165   1.168 1.163 1.166 1.172 1.165   1.171 1.164
B3LYPultrafine         1.174   1.175             1.166     1.162
B3PW91   1.194 1.194 1.198 1.173 1.173 1.173 1.164   1.166     1.170 1.163   1.170  
mPW1PW91   1.191   1.195 1.170 1.170 1.170 1.161 1.161 1.163     1.167 1.161   1.167  
M06-2X         1.168                        
PBEPBE   1.205     1.185 1.185 1.185 1.177 1.176 1.179 1.174   1.183 1.176     1.176
PBEPBEultrafine         1.184                        
PBE1PBE         1.170                        
HSEh1PBE         1.170                        
TPSSh         1.173   1.173             1.165      
Moller Plesset perturbation MP2   1.206 1.206 1.215 1.185 1.184 1.184 1.173 1.172     1.173 1.181 1.172   1.183  
MP2=FULL   1.206 1.206 1.214 1.184 1.183 1.184 1.172         1.180 1.170   1.182  
MP3         1.170   1.168                    
MP3=FULL         1.167   1.167                    
MP4       1.215 1.191                 1.179      
B2PLYP         1.179                 1.165      
B2PLYP=FULLultrafine         1.178                        
Configuration interaction CID         0.935                        
CISD   1.192     1.167                        
Quadratic configuration interaction QCISD   1.202 1.202 1.212 1.179 1.178 1.179 1.167 1.166       1.174 1.165      
QCISD(T)         1.183                        
Coupled Cluster CCD   1.195 1.195 1.204 1.173 1.172 1.173 1.161         1.168 1.160      
CCSD         1.176                        
CCSD(T)         1.182                        

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 1.199 1.158 1.193 1.152 1.187 1.187
density functional B1B95 1.214 1.183        
B3LYP 1.217 1.187 1.213 1.180 1.207 1.206
Moller Plesset perturbation MP2 1.233 1.196 1.228 1.190 1.222 1.222
Values that are outliers may reflect incorrect atom numbering for different levels of theory.
Please use the error report form to report problems.