We report calculations of energy levels and radiative rates for transitions among the lowest 116 fine-structure levels arising from the ⩽ n 5 configurations in Be-like ions with Z = 10-30. The wavelengths, oscillator strengths, line strengths, and radiative rates for all possible electric dipole, magnetic dipole, electric quadrupole, and magnetic quadrupole transitions among the 116 levels have been calculated using the combined configuration interaction and many-body perturbation method. The accuracy of the results is determined through extensive comparisons with existing laboratory measurements and theoretical results. The present complete set of results should be of great help in line identification and the interpretation of spectra, as well as in the modeling and diagnostics of astrophysical and fusion plasmas.

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The melting curve of lithium was computed using the Z -method microcanonical molecular-dynamics simulations for pressures up to 30 GPa. They show good agreement with the experimental and two-phase simulated results. The change of the melting line slope from positive to negative was predicted by the characteristic shape inversion of the Z curve at about 8.2 GPa. Through analyzing the static properties, we conclude that no liquid-liquid phase transition accompanies the occurrence of the melting line maximum, which is caused by the higher compressibility of the liquid phase compared to the solid phase. In addition, we systematically studied the dynamic and optical properties of lithium near the melting curve at critical superheating and melting temperatures. It was suggested that the spectra difference at critical superheating and melting temperature may be able to diagnose the homogeneous melting.