| State | Method | "Kekule" Mode, cm-1 |
FC, mDyne/Å |
Reduced mass, AMU |
Bond length, Å |
Data DOI |
|---|---|---|---|---|---|---|
| Cyclobutadiene | ||||||
| 3A1g | CCSD/Def2-SVP | 1422a | 7.7848 | 6.5340 | 1.444 | 6634 |
| 1373b | 7.9700 | 7.1807 | ||||
| 3A1g | CCSD(T)/Def-SVP | 1395 | 7.2647 | 6.3381 | 1.449 | 6643 |
| 1345 | 7.6931 | 7.2202 | ||||
| 3A1g | CCSD/Def2-TZVPP | 1392 | 6.9173 | 6.0600 | 1.438 | 6671 |
| 1342 | 8.0252 | 7.5582 | ||||
| 3A1g | CCSD(T)/Def2-TZVPP | 1360 | 7.2647 | 6.3381 | 1.449 | 6672 |
| 1310 | 7.7044 | 7.6151 | ||||
| 5B1g | CCSD/Def2-SVP | 1192 | 2.2102 | 2.6391 | 1.566 | 6635 |
| 1088 | 4.9656 | 7.1153 | ||||
| 5B1g | CCSD(T)/Def-SVP | 1176 | 2.0739 | 2.5452 | 1.569 | 6644 |
| 1069 | 4.7829 | 7.0983 | ||||
| 5B1g | CCSD/Def-TZVPP | 1177 | 1.8783 | 2.3023 | 1.563 | 6636 |
| 1067 | 5.0294 | 7.5000 | ||||
| 5B1g | CCSD(T)/Def-TZVPP | 1157 | 1.7555 | 2.2253 | 1.568 | 6678 |
| 1045 | 4.8322 | 7.5073 | ||||
| Cyclobutadiene Di-anion (isoelectronic with benzene) | ||||||
| 1A1g | CCSD/Def2-SVP | 1283 | 5.9023 | 6.0872 | 1.470 | 6652 |
| 1233 | 6.3831 | 7.1172 | ||||
| 1A1g | CCSD(T)/Def2-SVP | 1258 | 5.5888 | 5.9952 | 1.475 | 6653 |
| 1209 | 6.1657 | 7.1565 | ||||
| 1A1g | CCSD/Def2-TZVPP | 1216 | 4.3487 | 4.9883 | 1.467 | 6676 |
| 1165 | 6.2282 | 7.7827 | ||||
| 1A1g | CCSD(T)/Def2-TZVPP | 1187 | 4.1223 | 4.9621 | 1.473 | 6679 |
| 1138 | 6.0103 | 7.8734 | ||||
| Benzene | ||||||
| 1A1g | CCSD/Def2-SVP | 1337 | 4.9922 | 4.7425 | 1.401 | 6623 |
| 1308 | 10.7126 | 10.6244 | ||||
| 1A1g | CCSD(T)/Def2-SVP | 1359 | 6.9812 | 6.4190 | 1.405 | 6647 |
| 1339 | 11.3860 | 10.7785 | ||||
| 1A1g | CCSD/Def2-TZVPP | 1309 | 3.5714 | 3.5358 | 1.392 | 6646 |
| 1273 | 10.1936 | 10.6709 | ||||
| 1A1g | CCSD(T)/Def2-TZVPP | 1328 | 5.6130 | 5.4004 | 1.398 | 6710 |
| 1306 | 10.9097 | 10.8588 | ||||
| 5A1g | CCSD/Def2-SVP | 1600 | 17.4689 | 11.5855 | 1.463 | 6626 |
| 1597 | 17.4799 | 11.6274 | ||||
| 5A1g | CCSD/Def2-TZVPP | 1572 | 17.1041 | 11.7511 | 1.455 | 6669 |
| 1571 | 17.1770 | 11.8198 | ||||
| 7B1u | CCSD/Def2-SVP | 1361 | 11.0797 | 10.1574 | 1.550 | 6632 |
| 1355 | 12.4274 | 11.4839 | ||||
| Cyclo-octatetraene Dication (isoelectronic with benzene) | ||||||
| 1A1g | CCSD/Def2-SVP | 1750 | 21.4531 | 11.8876 | 1.414 | 6648 |
| 1750 | 21.5770 | 11.9620 | ||||
| 1A1g | CCSD(T)/Def2-SVP | 1707 | 20.4695 | 11.9226 | 1.420 | 6673 |
| 1707 | 20.5570 | 11.9773 | ||||
| 5A1g | CCSD/Def2-SVP | 1702 | 20.4349 | 11.9684 | 1.444 | 6663 |
| 1702 | 20.4690 | 11.9899 | ||||
| 7B1g | CCSD/Def2-SVP | 1460 | 14.8761 | 11.8407 | 1.511 | 6675 |
| 1460 | 15.0578 | 11.9890 | ||||
| Cyclo-octatetraene | ||||||
| 3B2g | CCSD/Def2-SVP | 1777 | 22.3143 | 11.9956 | 1.409 | 6637 |
| 1777 | 22.3176 | 11.9976 | ||||
| 7A1g | CCSD/Def2-SVP | 1637 | 18.9335 | 11.9851 | 1.484 | 6639 |
| 1637 | 18.9464 | 11.9941 | ||||
| 9B1g | CCSD/Def2-SVP | 1441 | 14.6711 | 11.9988 | 1.553 | 6640 |
| 1441 | 14.6723 | 11.9998 | ||||
| 9B1g | CCSD(T)/Def2-SVP | 1421 | 13.4795 | 11.3256 | 1.555 | 6677 |
| Cyclo-octatetraene dianion | ||||||
| 1A1g | CCSD/Def2-SVP | 1731 | 21.1621 | 11.9903 | 1.419 | 6695 |
| 1731 | 21.1668 | 11.9937 | ||||
| 5A1g | CCSD/Def2-SVP | 1642 | 19.0214 | 11.9711 | 1.461 | 6698 |
| 1642 | 19.0408 | 11.9852 | ||||
| 9B2u | CCSD/Def2-SVP | 1517 | 16.0290 | 11.8174 | 1.528 | 6700 |
| 1517 | 16.1516 | 11.9186 | ||||
aUnprojected, with possible Dushinsky coupling bProjected from Dushinksky coupling.
Badger's rule for diatomics. ko(re - 0.68)3 = 1.86 x 105 Plot cube root of 1/ko vs bond length