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A MO-theoretical calculation of the antiferromagnetism in the γ-phase of p-nitrophenyl nitronyl nitroxide

✍ Scribed by M. Okumura; W. Mori; K. Yamaguchi

Publisher
Elsevier Science
Year
1994
Tongue
English
Weight
767 KB
Volume
219
Category
Article
ISSN
0009-2614

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✦ Synopsis

Semi-empirical and ab initio molecular orbital (MO) calculations have been carried out for clusters ofpnitrophenyl nitronyl nitroxide (p-NPNN) extracted from the experimental crystal structure of its y-phase. It is found that the intraplane exchange interactions (Jab) are ferromagnetic, whereas the interplane one is antiferromagnetic. The antiferromagnetic transition temperature (TN) is estimated by a generalized Langevin-Weiss-NCel (GLWN) model combined with the calculated Jab values by the MO methods. The Neel temperature (TN) by the mean-field GLWN model is of the order of the experimental value, although the former is much larger than the latter because of the low dimensionality of the y-phase. A systematic theoretical explanation is presented for the magnetic long-range orderings in the /3-and y-phase crystals of pNPNN.

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