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Information × Registration Number 0221U105225, 0120U104702 , R & D reports Title Revealing new properties of disordered materials at extremal conditions: Ab initio simulation approach popup.stage_title Head Bryk Taras M., Registration Date 14-06-2021 Organization Institute of Condensed Matter Physics of the National Academy of Sciences of Ukraine popup.description2 Upon the realization of the project it was estimated the existence of two branches of transverse short-wavelength excitations in the second pseudo-Brillouin zone in Si melt, and at high pressures the frequencies of these transverse modes correspond to the peaks in the spectrum of the single-particle velocity autocorrelation function. Having as examples a sequence of polyvalent metallic melts it was estimated an universal linear behavior of high-frequency transverse modes with the increase of the system density, while the universal dependence is superimposed on a single line with the slope identical for all studied polyvalent metals. For binary melts SiO2 and TlTe the ab initio simulations allowed to estimate the existence of high-frequency modes, which are the analogue of optic phonons in ionic crystals, which however have essentially stronger damping as in non-hydrodynamic processes. The study of carbon melt at extremely high temperatures allowed to estimate, that collective modes contributing along with the acoustic excitations to the longitudinal dynamics have the analogy with optic modes in carbon crystals because of the existing covalent bonds. Product Description popup.authors Hordijchuk Volodymyr V. Demchuk Taras V. Trokhymchuk Andrij D. popup.nrat_date 2021-06-14 Close