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XVII.C.1.

Calculated Ionization Energy for C3 (carbon trimer)

Experimental Ionization Energy is 13 ± 0.1 eV
Please note! These calculated ionizataion energies have the vibrational zero-point energy (zpe) included, but the zpe has NOT been scaled. Click on an entry for more details, including the ionization energy with a scaled zpe.
Original data displayed. Press to display differences.
Differences displayed. Press to display original data.

Ionization Energies in eV
Methods with predefined basis sets
semi-empirical AM1  
PM3  
PM6  
composite G2 11.812
G3 11.823
G3B3 12.284
G4 12.326
CBS-Q 11.792

Ionization Energies in eV
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) TZVP cc-pVDZ cc-pVTZ cc-pVQZ aug-cc-pVDZ aug-cc-pVTZ aug-cc-pVQZ
hartree fock HF 10.453 12.658 12.658 12.491 12.538 12.538 12.689 12.708 12.708 12.536 11.728 12.671 12.692 12.696 12.715 12.698 12.697
density functional LSDA 10.203 12.135 12.135 11.968 12.073 12.073 12.296 12.338 12.338 12.118   12.239 12.339   12.325 12.357  
SVWN   12.135     12.073   12.296                    
BLYP 9.577 11.405 11.405 11.263 11.349 11.349 11.611 11.592 11.592 11.403   11.523 11.617        
B1B95 10.358 12.158 12.158 11.976 12.048 12.048 12.316 12.236 12.235 12.074   12.191 12.227   12.247 12.236  
B3LYP 9.615 12.920 12.920 12.262 12.208 12.208 12.407 12.393 12.393 12.243 12.419 12.354 12.404 12.409 12.419 12.421 12.415
B3LYPultrafine         12.208                     12.421  
B3PW91 10.417 12.249 12.249 12.040 12.103 12.103 12.273 12.285 12.285 12.123   12.240 12.277        
mPW1PW91 10.331 12.245 12.245 12.046 12.122 12.122 12.300 12.302 12.302 12.137   12.257 12.295        
M06-2X         12.386                        
PBEPBE 9.669 11.539 11.539 11.363 11.446 11.446 11.669 11.663 11.663 11.479   11.601 11.680        
PBE1PBE         12.076                        
HSEh1PBE         12.056                        
TPSSh             12.119                    
Moller Plesset perturbation MP2 8.086 10.709 10.709 10.518 10.816 10.816 11.037 11.073 11.073 11.058 11.060 11.020 11.262   11.177 11.312  
MP2=FULL 8.085 10.710 10.710 10.518 10.822 10.822 11.042 11.082 11.082 11.069   11.023 11.277     11.327  
MP3         12.013                        
MP3=FULL         12.167   12.406                    
MP4         17.051       15.596       17.623        
B2PLYP         11.575                        
Configuration interaction CID   11.511 11.511 11.384 11.892     12.317                  
CISD   11.392 11.392 11.261 11.795     12.210                  
Quadratic configuration interaction QCISD   10.977 10.977 10.846 11.466 11.466 11.678 11.724 11.724 11.748   11.706 11.948        
QCISD(T)         13.693             13.913 14.140     14.236  
Coupled Cluster CCD   11.268 11.268 11.140 11.726 11.726 12.108 12.179 12.179 12.193   12.106 12.234   12.247 12.432  
CCSD         11.594                        
CCSD(T)                       13.937       12.035  
CCSD(T)=FULL         13.668                        

Ionization Energies in eV
Methods with effective core potentials (select basis sets)
CEP-31G CEP-31G* CEP-121G CEP-121G* LANL2DZ SDD
hartree fock HF 12.576 12.628 12.585 12.674 12.640 12.637
density functional B3LYP 12.199 12.230 12.220 12.282 12.440 12.427
Moller Plesset perturbation MP2 10.658 10.970 10.714 11.027 10.665 10.666
For descriptions of the methods (AM1, HF, MP2, ...) and basis sets (3-21G, 3-21G*, 6-31G, ...) see the glossary in section I.C. Predefined means the basis set used is determined by the method.