Geometry optimization of periodic systems



  Dear collegues
  I am looking for references that describe geometry optimization methods
 for periodic systems, and their applications. Specifically, I would like
 to know about any algorithm that employs something more complicated than
 the usual Cartesian coordinates for atomic positions and lattice vectors.
 An example of such more elaborate method would be a variable-cell-shape
 (VCS) algorithm which optimizes the dot products between the lattice
 vectors instead of the Cartesian components of these vectors.
 {I. Souza and J.L. Martins, Phys. Rev. B, 55, 8733 (1997).}
  Regards,
  Konstantin Kudin