return to home page

XVII.C.1.

Calculated Ionization Energy for C2H (Ethynyl radical)

Experimental Ionization Energy is 11.61 ± 0.07 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 PM3  
PM6  
composite G4 11.809
CBS-Q 11.689

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) cc-pVDZ cc-pVTZ cc-pVQZ aug-cc-pVDZ aug-cc-pVTZ aug-cc-pVQZ
hartree fock HF 8.640 10.327 10.327 10.107 8.139 9.927 9.997 10.042 10.044 9.880 10.004 10.011 10.012 10.004 10.011 10.011
density functional LSDA 10.895 12.381 12.381 12.172 12.107 12.110 12.270 12.346 12.343 12.128 12.222 12.341   12.281    
SVWN   14.857         14.916                  
BLYP 9.993 11.452 11.452 11.250 11.192 11.193 11.395 11.414 11.422 11.208 11.318 11.445        
B1B95 10.204 11.571 11.570 11.353 11.223 11.263 11.422 11.423 11.428 11.266 11.359 11.434   11.420    
B3LYP 10.175 11.612 11.612 11.405 11.354 11.348 11.546 11.540 11.539 11.303   11.533 11.556 11.538 11.575 11.559
B3LYPultrafine         11.354                      
B3PW91 10.204 11.640 11.640 11.398 11.317 11.296 11.428 11.474 11.477 11.300 11.395 11.472        
mPW1PW91 10.159 11.580 11.602 11.357 11.229 11.221 11.362 11.394 11.419 11.244 11.320 11.397        
PBEPBE 10.151 11.611 11.611   11.320 11.321 11.488 11.508 11.520 11.329 11.433 11.534        
PBE1PBE         11.248                      
TPSSh             14.622                  
Moller Plesset perturbation MP2 9.102 10.973 10.973 10.747 10.918 10.941 11.088 11.167 11.200 11.153 11.086 11.388   11.188 11.425  
MP2=FULL   10.976     10.934 10.957 11.104 11.183 11.217   11.097 11.430        
MP3         10.799                      
MP3=FULL         13.741   13.905                  
MP4         10.918             13.849        
B2PLYP                       14.408        
Configuration interaction CID         10.695     10.903                
CISD         10.737                      
Quadratic configuration interaction QCISD   11.117     10.987 11.009 11.129 11.188     11.141 11.372        
QCISD(T)         11.062                      
Coupled Cluster CCD         10.814     11.034     10.969          
CCSD(T)         11.055             11.483        

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 10.039 9.850 10.151 9.976 10.205 10.207
density functional B3LYP 11.225 11.034   11.392 11.552 11.532
Moller Plesset perturbation MP2 10.559 10.748 10.812 11.009 10.865 10.871
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.