Premium
Ab initio MO and approximate density functional theory studies on the lowest singlet and triplet states of s and as ‐indacene
Author(s) -
Hertwig Roland H.,
Holthausen Max C.,
Koch Wolfram,
Maksí Zvonimir B.
Publication year - 1995
Publication title -
international journal of quantum chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.484
H-Index - 105
eISSN - 1097-461X
pISSN - 0020-7608
DOI - 10.1002/qua.560540303
Subject(s) - ab initio , singlet state , density functional theory , chemistry , triplet state , electronic structure , molecule , ab initio quantum chemistry methods , physics , computational chemistry , quantum mechanics , excited state
The lowest singlet and triplet states of s ‐ and as ‐indacene have been studied by means of high‐level ab initio MO and approximate density functional methods. Among the geometrical and energetical details discussed are the equilibrium structure of s ‐indacene ( C 2 h or D 2 h ), the structures and energies of the low‐lying s ‐indacene triplet states, and the stability and geometry of the singlet and triplet states of as ‐indacene. It is shown that single‐determinant‐based methods, such as Hartree‐Fock or MP 2, are not suited to properly describe these molecules. Instead, methods are required which explicitly take into account nondynamical and dynamical electron correlation. The results obtained by density functional theory‐based methods compare very well with the most elaborate ab initio MO data and seem to provide an economical alternative even for molecules with a complicated electronic structure such as s ‐ and as ‐indacene. © 1995 John Wiley & Sons, Inc.