G.D. Chebotarev - D.Sc. (Phys.-Math.), Professor, Department of physics, Southern Federal University. E-mail: g_chebotarev@mail.ru
E.L. Latush - D.Sc. (Phys.-Math.), Professor, Department of physics, Southern Federal University. E-mail: ellatush@sfedu.ru
A.A. Fesenko - Assistant, Department of physics, Southern Federal University. E-mail: fesenko82@mail.ru