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Calculated Proton Affinity

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Name Species   Species Name
imidizolyl anion C3H3N2- C3H4N2 4H-Imidazole

Bonding changes

Bond type H-C changed by +2
Bond type H-N lost 1
Bond type N-N lost 1
Bond type C-C gained 1
Proton Affinities (kJ/mol)
Proton Affinities in kJ/mol
Methods with predefined basis sets
composite G1  
G2MP2  
G2 1357
G3 1358
G3B3 1361
G4 1360
CBS-Q 1352

Proton Affinities in kJ/mol
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 aug-cc-pVDZ aug-cc-pVTZ
hartree fock HF 1759 1460 1460 1432 1469 1472 1427 1455 1457 1482 1438 1462 1451 1432 1435
density functional LSDA 1664 1407 1407 1380 1397 1398 1341 1368 1369 1399 1348 1383 1359 1339 1341
SVWN   1407     1397 1398 1341 1368 1369 1399   1383 1359 1339 1341
BLYP 1702 1459 1459 1431 1448 1450 1383 1418 1419 1450 1394 1431 1407    
B1B95 1689 1439 1439 1414 1434 1449 1387 1414 1415 1440 1397 1423 1407 1386 1390
B3LYP 1702 1452 1452 1425 1446 1448 1389 1420 1421 1450 1398 1431 1410 1387 1390
B3LYPultrafine         1446           1398 1431 1410 1387 1390
B3PW91 1697 1443 1443 1419 1439 1441 1392 1417 1418 1444 1400 1428 1411    
mPW1PW91 1697 1441 1441 1417 1438 1440 1391 1417 1418 1444 1401 1427 1411 1391 1394
M06-2X 1699 1432 1421 1404 1421 1423 1375 1401 1402 1427 1383 1410 1392 1376 1377
PBEPBE 1693 1442 1442 1417 1433 1436 1377 1408 1409 1437 1388 1420 1399 1375 1378
PBEPBEultrafine         1433           1388 1420 1399 1375 1378
PBE1PBE 1697 1437 1437 1413 1434 1434 1386 1413 1414 1440 1395 1423 1406 1386 1389
HSEh1PBE 1697 1438 1438 1413 1434 1437 1233 1413 1414 1440 1395 1423 1406 1386 1388
TPSSh   1450 1450 1426 1446 1448 1397 1424   1451 1407 1435 1418 1397 1400
wB97X-D     1447   1444   1396   1423   1405 1396 1416   1400
B97D3   1463     1456       1433           1403
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 aug-cc-pVDZ aug-cc-pVTZ
Moller Plesset perturbation MP2 1784 1458 1458 1420 1418 1434 1373 1395 1408 1419 1386 1415 1385 1358  
MP2=FULL 1784 1458 1458 1420 1418 1434 1373 1395 1408 1422 1386 1415 1387 1359 1363
MP3         1448   1375       1423 1448      
MP3=FULL         1448   1410       1423 1448 1425    
MP4   1480     1443       1434   1411   1410 1385 1384
MP4=FULL   1480                   1442 1412    
B2PLYP 1732 1455 1455 1424 1439 1445 1386 1415 1419 1442 1397 1428 1405 1380 1382
B2PLYP=FULL 1732 1455 1455 1424 1439 1445 1386 1414 1419 1443 1397 1428 1405 1380  
Configuration interaction CID   1474 1474 1439 1452     1435              
CISD   1475 1475 1440 1453     1436              
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 aug-cc-pVDZ aug-cc-pVTZ
Quadratic configuration interaction QCISD   1491 1491 1452 1457 1472 1415 1437 1449 1462   1456 1430 1406  
QCISD(T)         1452           1421 1451 1422    
Coupled Cluster CCD   1487 1487 1448 1452 1467 1412 1432 1445 1457 1425 1451 1426 1402  
CCSD         1456           1428 1455 1429 1405  
CCSD=FULL         1455           1428 1455 1431 1406  
CCSD(T)         1452           1421 1451 1421 1397  
CCSD(T)=FULL         -7023           1421 1451      
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 aug-cc-pVDZ aug-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
hartree fock HF 1412 1450 1408 1444 1408 1408
density functional B3LYP 1399 1423 1392 1414 1396 1396
Moller Plesset perturbation MP2 1391 1395 1382 1384 1386 1386
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.