The 1A1 π→π* state of formaldehyde

✍ Scribed by Stephen R. Langhoff; Stephen T. Elbert; Charles F. Jackels; Ernest R. Davidson

• Publisher: Elsevier Science
• Year: 1974
• Tongue: English
• Weight: 326 KB
• Volume: 29
• Category: Article
• ISSN: 0009-2614
• DOI: 10.1016/0009-2614(74)85025-6

✦ Synopsis

There have been several papers published recently which differ significantly on the energy and nature of the 1 A, T-W.* state of formaldehyde. Buenker and Peyerimhoff [l] using a basis set without diffuse orbitals obtained an.excitation ener,g of 11.72 eV. In this calculation the T-W_* state appeared as the second root of the secular equation and fhe 3A, SCF orbitals were used io construct the configurations. In a later paper Peyerimhoff et al. [2] obtained an excitation energy of 11.41 eV. In this calculation diffuse basis functions were included to represent some Rydberg states. The W* state appeared as the third root of the secular equation based on 3AI SCF orbit&. Both of these calculations miss the ground state SCF energy by about 2 eV and account for less than 10 % of the correlation energy.

2.5 % of the correlation energy. Effuse basis functions, however, were used only in the bl(%) subspace. He feit this would a&w the proper size adjustment of the 7r and n* orbit&. Because diffuse b, orbit& were not included, the lower energy b, + bj Rydberg states were not present in the secular equation. He found the 71 and + orbit& were not particaiarly diffuse.