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Calculated Proton Affinity

20 10 26 10 44
Name Species   Species Name
carbon diatomic anion C2- C2H Ethynyl radical

Bonding changes

Bond type C=C lost 1
Bond type C#C gained 1
Bond type H-C gained 1
Proton Affinities (kJ/mol)
Proton Affinities in kJ/mol
Methods with predefined basis sets
semi-empirical PM3  
composite G4 1455

Proton Affinities in kJ/mol
Methods with standard basis sets
STO-3G 3-21G 3-21G* 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 aug-cc-pVDZ aug-cc-pVTZ cc-pV(T+d)Z daug-cc-pVTZ
hartree fock HF                               1589 1572
ROHF         1604                        
density functional LSDA 1868     1509     1460                 1453  
BLYP         1536                     1481  
B1B95                               1498  
B3LYP                               1493  
B3LYPultrafine                             1470    
B3PW91                               1500  
mPW1PW91                               1502  
M06-2X     1557                            
PBEPBE                               1480  
PBE1PBE         1540                        
HSEh1PBE         1541                        
TPSSh         1543               1497        
wB97X-D     1555   1546 1476   1515     1492 1476 1505   1485    
B97D3         1508 1434   1472   1436 1470   1484        
STO-3G 3-21G 3-21G* 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 aug-cc-pVDZ aug-cc-pVTZ cc-pV(T+d)Z daug-cc-pVTZ
Moller Plesset perturbation MP2         1464   1420                 1422  
MP2=FULL                           1377   1434  
MP3           1522                      
MP3=FULL         1516 1461                      
MP4                         1430        
B2PLYP                         1480        
STO-3G 3-21G 3-21G* 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 aug-cc-pVDZ aug-cc-pVTZ cc-pV(T+d)Z daug-cc-pVTZ
Quadratic configuration interaction QCISD                               1506  
Coupled Cluster CCSD(T)                               1491  
STO-3G 3-21G 3-21G* 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 aug-cc-pVDZ aug-cc-pVTZ cc-pV(T+d)Z daug-cc-pVTZ

Proton Affinities in kJ/mol
Methods with effective core potentials (select basis sets)
CEP-31G CEP-31G* CEP-121G CEP-121G* LANL2DZ SDD cc-pVTZ-PP aug-cc-pVTZ-PP Def2TZVPP
hartree fock HF                 1579
density functional B3LYP                 1481
PBEPBE                  
Moller Plesset perturbation MP2                 1410
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.