Ab initio electronic-structure calculations, based on the density-functional theory and the full-potential linear-muffin-tin-orbital method, were used to predict crystal-sructure phase stabilities and elastic constants of beryllium under compression. Specific energies, pressures, elastic constants, and Debye temperatures for three crystal structures, hcp, bcc, and fcc, were calculated over a wide volume range. In agreement with experiments and previous theoretical calculations, the hcp ground state is obtained at ambient conditions and the bcc ground state is found at high pressure and ambient temperature, with the predicted $\mathrm{hcp}\to \mathrm{bcc}$ phase transition at about 2.7 Mbar. A possible phase diagram of beryllium, including hcp, bcc, and fcc phases is constructed in the $(P,T)$ plane.

The paper investigates the interaction of femtosecond laser pulses with the thin films of copper, gold, and platinum. It considers electron-phonon relaxation processes and melting in the metal system nonequilibrium heated by laser radiation. Instead of the approximated formula by Wang et al. [ Phys. Rev. B 50, 8016 (1994)], which is widely used to determine the temperature dependence of the electron-phonon coupling factor, we propose an improved approach for its more accurate calculation from first principles. Comparison with experiments and other calculations shows our approach to provide good calculation accuracy. Melting time versus absorbed energy density was estimated for the films and shown to be markedly sensitive to latent heat at low absorbed energy densities $(<1$ MJ/kg). Our calculations taken to study the temporal evolution of the (220) diffraction peak intensity after femtosecond irradiation show good agreement between experimental and theoretical data, which was attained due to higher accuracy in our determination of the temperature dependence electron-phonon coupling factor.

This paper presents results obtained in ab initiocalculations of the thermodynamic properties of B1 and B2 lithium fluoride under pressure. The data were used to calculate LiF isotherms and isochors at pressures from 0 to 500 GPa and temperatures up to the melting point. Calculated results are compared with available theoretical and experimental data on the shock and static compression of LiF crystal. Based on the analysis of our calculations and available experimental data, a hypothetical (P,T) diagram of LiF which includes the crystalline phases B1 and B2 and liquid is proposed.

The equations of state at room temperature as well as the energies of crystal structures up to pressures exceeding 100 GPa are calculated for Na and K. It is shown that allowance for generalized gradient corrections in the density functional method provides a precise description of the equation of state for Na, which can be used for the calibration of a pressure scale. It is established that the close-packed structures and bcc structure are not energetically advantageous at high enough compressions. Sharply nonmonotonic pressure dependences of elastic moduli for Na and K are predicted, and melting temperatures at high pressures are estimated from various melting criteria. The phase diagram of K is calculated and found to be in good agreement with experiment.