[en] We discuss two examples of computer simulation of liquid semiconductors by two different techniques. Both examples are concerned with the relationship between thermodynamic properties and the atomic structure in the liquid state. By means of ab initio molecular dynamics we analyze the atomic structure of liquid Ge15Te85 eutectic alloys. We show that the changes observed in the experimental total structure factor S(q) are located in the GeTe partial structure factor, the TeTe partial structure factor remaining essentially unaltered. Using a semi-empirical tight binding approach, coupled with Gibbs ensemble and constant pressure Monte Carlo calculations, we can calculate the liquid vapor equilibrium of selenium. We obtain a liquid-vapor equilibrium curve and a critical point in the correct range of magnitude and an atomic structure of the liquid phase in good agreement with the experimental data. (C) 2002 Elsevier Science B.V. All rights reserved.