Geometry optimization of solids using delocalized internal coordinates

A new algorithm is presented that uses delocalized internal coordinates to optimize structures of periodic systems. The algorithm employs translational symmetry to construct the B matrix. It requires generation of all unique primitive internals in the unit cell. B is subsequently used to generate a set of delocalized internals as described in the earlier work by Pulay, Baker and coworkers for molecular systems. A detailed analysis of the algorithm for bulk Si is given, and the performance of the method in applications to surface reactions and zeolites is briefly mentioned. (C) 2001 Elsevier Science B.V. All rights reserved.