Structural stability is of fundamental importance in materials science. Up-to-date information on the theoretical aspects of phase stability of materials is contained in this volume. Most of the first-principles calculations are based on the local-density approximation (LDA). In contrast, this volume contains very recent results of "going beyond LDA," such as the density gradient expansion and the quantum Monte-Carlomethod. Following the recently introduced theoretical methods for the calculation of interatomic potentials, forces acting on atoms and total energies such as the Car-Parrinello,...