Vertical and adiabatic electronic excitations in biphenylene: A theoretical study

Autor:	Georg Hohlneicher, Bjoern O. Roos, Luis Serrano-Andrés, Rupert Rebentisch, M. E. Beck, Markus P. Fülscher
Rok vydání:	1997
Předmět:	chemistry.chemical_compound chemistry Excited state Ab initio General Physics and Astronomy Complete active space Singlet state Physical and Theoretical Chemistry Perturbation theory Atomic physics Biphenylene Adiabatic process Ground state
Zdroj:	The Journal of Chemical Physics. 107:9464-9474
ISSN:	1089-7690 0021-9606
DOI:	10.1063/1.475243
Popis:	The low-lying singlet states of biphenylene have been studied using ab initio methods. Vertical excitation energies were calculated by multiconfigurational perturbation theory (CASPT2), starting from a complete active space self-consistent field (CASSCF) reference. The geometries of the most important low-lying excited states were individually optimized at the CASSCF level to study the difference between vertical and adiabatic excitations. Extended atomic natural orbital (ANO)-type basis sets were used to calculate state energies. Geometry optimizations were done with smaller ANO-type basis sets. Excitations from the ground state to the 1 1B3g and 1 1B2u excited singlet states lead to pronounced geometry changes which alter the bond alternation pattern. The theoretical results provide a solid basis for the assignment and interpretation of experimental spectra.
Databáze:	OpenAIRE
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