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Mixing of frenkel excitons and ionic excited states of a linear molecular crystal with two molecules in the unit cell I. General model
Author(s) -
Petelenz P.
Publication year - 1976
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.2220780208
Subject(s) - hamiltonian (control theory) , excited state , ionic bonding , exciton , ionic crystal , crystal (programming language) , molecule , physics , mixing (physics) , quantum mechanics , mathematics , ion , computer science , mathematical optimization , programming language
The Merrifield theory of the interaction between the neutral and ionic excited states of a linear molecular crystal is generalized for crystals with two molecules in the unit cell. It is demonstrated that the Hamiltonian can be split into three communting terms. For two of them the original Merrifield theory is directly applicable and its conclusions are valid. The third term describes the mixing between the (+) Davydov component of the Frenkel exciton, the (+) intra‐cell CT exciton, and the (+) lengthwise and (+) crosswise ionic pair states. It can no more be treated within the frame of the original Merrifield theory. However it can be further transformed to a renormalized form which consists of two decoupled Hamiltonians. Both of them are formally analogous to the Merrifield Hamiltonian but with renormalized effective parameters. In the result some ionic states become active in the absorption spectrum.