I.G. Ivanov - Dr. Sc. (Phys.-Math.), Professor, Department of Physics, Southern Federal University (Rostov-on-Don). E-mail: ig.ivanov@mail.ru A.M. Bessmertny -Student, Department of Physics, Southern Federal University (Rostov-on-Don). E-mail: bes93@mail.ru

I.G. Ivanov - Dr. Sc. (Phys.-Math.), Professor, Department of Physics, Southern Federal University (Rostov-on-Don). E-mail: ig.ivanov@mail.ru A.M. Bessmertny - Student, Department of Physics, Southern Federal University (Rostov-on-Don). E-mail: bes93@mail.ru