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Theory of singlet–triplet splitting of M‐ and F t ‐centres in ionic crystals
Author(s) -
Berezin A. A.
Publication year - 1972
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.2220490103
Subject(s) - singlet state , ionic bonding , electron , halide , lattice (music) , chemistry , physics , energy level splitting , alkali metal , atomic physics , ion , quantum mechanics , inorganic chemistry , excited state , acoustics
The modified method of Gorkov‐Pitaevskii and Herring‐Flicker is used for the calculation of the value of singlet–triplet splitting in the system of two interacting F‐centres. The energy of singlet–triplet splitting (Δ) is expressed by a five‐dimensional integral in the configuration space of two optical electrons which for the case of 1s hydrogen‐like wave functions of F‐centres can be computed in explicit form. The numerical results are given for the M‐centre in alkali halides and the F t ‐centre (two electrons trapped by a linear trivacancy) in alkaline earth oxides (MgO and CaO). For these centres the calculated values of Δ are in good agreement with the experimental ones. It is shown that the theoretical values of Δ obey the Mollwo‐Ivery relation of the form Δ ∼ d −n ( d lattice constant), where n ≈ 2.3 for the M‐centre and n ≈ 0.5 to 0.9 for the F t ‐centre.