D.N. Sokolov - Postgraduate student of department of the theoretical physics, Tver State University. E-mail: dnsokolov@mail.ru
N.Yu. Sdobnyakov - Associate professor of department of the theoretical physics, Tver State University. E-mail: nsdobnyakov@mail.ru
A.Yu. Kolosov - Postgraduate student of department of the theoretical physics, Tver State University. E-mail: kolosov-au@yandex.ru
N.V. Novozhilov - Postgraduate student of department of the theoretical physics, Tver State University. E-mail: nnowhereman@gmail.com
A.S. Antonov - Postgraduate student of department of the theoretical physics, Tver State University. E-mail: s014451@mail.ru