Geometry Comparison
C2H2 (Acetylene)
distance is atom 1 (C) to atom 2 (C)
Experimental bond length is 1.203 Å
original data displayed. press to display differences
differences displayed. press to display original data
Calculated bond length in Å
Methods with predefined basis sets
| semi-empirical |
PM3 |
1.190 |
| PM6 |
1.205 |
| composite |
G2 |
1.185 |
| G3 |
1.185 |
| G3B3 |
1.205 |
| CBS-Q |
1.188 |
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 |
Sadlej_pVTZ |
| hartree fock |
HF |
1.168 |
1.188 |
1.188 |
1.194 |
1.185 |
1.186 |
1.189 |
1.183 |
1.182 |
1.181 |
1.180 |
1.181 |
1.192 |
1.180 |
1.179 |
1.192 |
1.180 |
1.179 |
|
|
1.192 |
| density functional |
LSDA |
1.207 |
1.208 |
1.208 |
1.216 |
1.211 |
1.211 |
1.213 |
1.202 |
1.202 |
1.205 |
|
|
1.215 |
1.200 |
|
1.215 |
|
|
|
|
|
| BLYP |
1.213 |
1.213 |
1.213 |
1.220 |
1.215 |
1.215 |
1.218 |
1.208 |
1.207 |
1.209 |
|
|
1.220 |
1.205 |
|
1.220 |
|
|
|
|
|
| B1B95 |
1.199 |
1.203 |
1.203 |
1.210 |
1.203 |
1.204 |
1.207 |
1.198 |
1.198 |
1.198 |
|
|
1.208 |
1.194 |
|
1.207 |
|
|
|
|
|
| B3LYP |
1.201 |
1.204 |
1.204 |
1.211 |
1.205 |
1.205 |
1.208 |
1.199 |
|
1.199 |
1.196 |
1.198 |
1.210 |
1.196 |
1.195 |
1.210 |
1.196 |
1.196 |
|
|
1.214 |
| B3LYPultrafine |
|
|
|
|
1.205 |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| B3PW91 |
|
1.205 |
1.205 |
1.211 |
1.206 |
1.206 |
1.208 |
1.200 |
|
1.200 |
|
|
1.210 |
1.197 |
|
1.210 |
|
|
|
|
|
| mPW1PW91 |
|
1.203 |
|
1.210 |
1.203 |
1.204 |
1.206 |
1.198 |
1.197 |
1.198 |
|
|
1.208 |
1.195 |
|
1.208 |
|
|
|
|
|
| M06-2X |
|
|
|
|
1.202 |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| PBEPBE |
|
1.214 |
|
|
1.216 |
1.216 |
1.219 |
1.209 |
1.209 |
1.210 |
1.207 |
|
1.220 |
1.207 |
|
|
1.207 |
|
|
|
1.225 |
| PBEPBEultrafine |
|
|
|
|
1.216 |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| Moller Plesset perturbation |
MP2FC |
|
1.222 |
1.222 |
1.232 |
1.218 |
1.219 |
1.221 |
1.216 |
1.215 |
1.212 |
|
1.211 |
1.230 |
1.211 |
1.209 |
1.231 |
1.212 |
|
1.228 |
1.210 |
1.234 |
| MP2FU |
|
1.222 |
|
|
1.216 |
1.217 |
1.219 |
1.215 |
|
|
|
|
1.229 |
1.207 |
|
1.231 |
1.208 |
|
1.227 |
1.208 |
|
| MP3 |
|
|
|
|
1.206 |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| MP4 |
|
|
|
|
1.220 |
|
|
1.219 |
|
|
|
|
|
1.213 |
|
|
|
|
|
|
|
| B2PLYP |
|
|
|
|
|
|
1.213 |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| Configuration interaction |
CID |
|
|
|
|
1.203 |
|
|
1.201 |
|
|
|
|
|
|
|
|
|
|
|
|
|
| CISD |
|
|
|
|
1.205 |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| Quadratic configuration interaction |
QCISD |
|
1.218 |
|
|
1.213 |
|
1.215 |
1.211 |
1.210 |
|
|
|
1.224 |
1.204 |
|
|
|
|
|
|
|
| QCISD(T) |
|
|
|
|
1.217 |
|
|
1.216 |
|
|
|
|
|
|
|
|
|
|
|
|
|
| Coupled Cluster |
CCD |
|
|
|
|
1.209 |
|
1.212 |
1.207 |
|
|
|
|
1.221 |
1.201 |
|
1.222 |
1.202 |
|
|
|
|
| CCSD |
|
|
|
|
1.212 |
|
|
1.210 |
|
|
|
|
|
|
|
|
|
|
|
|
|
| CCSD(T) |
|
1.221 |
|
|
1.217 |
1.218 |
1.220 |
1.215 |
1.215 |
|
|
|
1.229 |
1.210 |
|
1.230 |
1.210 |
|
1.227 |
1.209 |
|
| CCSD(T)=FULL |
|
|
|
|
1.216 |
|
|
|
|
|
|
|
1.228 |
1.206 |
|
1.229 |
1.206 |
|
1.226 |
1.207 |
|
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 |
1.227 |
1.221 |
1.201 |
1.190 |
1.202 |
1.201 |
| density functional |
B1B95 |
1.248 |
1.244 |
|
|
|
|
| B3LYP |
1.248 |
1.243 |
1.222 |
1.211 |
1.222 |
1.222 |
| Moller Plesset perturbation |
MP2FC |
1.275 |
1.257 |
1.243 |
1.224 |
1.246 |
1.245 |
Values that are outliers may reflect different atom numbering for
different levels of theory.
Please use the error
report form to report problems.
