1. Institute of Mathematics, Information Technologies and Physics, Udmurt State University, Izhevsk 426034, Russia; Vereshchagin Institute for High Pressure Physics, Russian Academy of Sciences, Moscow (Troitsk) 108840, Russia
2. Institute of Mathematics, Information Technologies and Physics, Udmurt State University, Izhevsk 426034, Russia
3. Institute of Mathematics, Information Technologies and Physics, Udmurt State University, Izhevsk 426034, Russia; Udmurt Federal Research Center Ural Branch of the Russian Academy of Science, Izhevsk 426067, Russia