1. Department
of Applied Mathematics, Kazan (Volga Region) Federal University, 420008 Kazan, Russia
2. GZG
Abt. Kristallographie, Georg-August-Universität Göttingen, 37077 Göttingen, Germany
3. Institut Laue-Langevin (ILL), 71 avenue des Martyrs, 38000 Grenoble, France