Since 1972 the Schools on Nonlinear Physics in Gorky have been a meeting place for Soviet scientists working in this field. Instead of producing for the first time English proceedings it has been decided to present a good cross section of nonlinear physics in the USSR. Thus the participants at the last School were invited to provide English reviews and research papers for these two volumes (which in the years to come will be followed by the proceedings of forthcoming schools). The first volume starts with a historical overview of nonlinear dynamics from Poincare to the present day and...

Theoretical and numerical details of an optimized LCAO (linear combination of atomic orbitals) method for the calculation of self-consistent bandstructures are given together with a variety of examples. The method will be a valuable tool both for researchers engaged in calculations and for scientists looking for numerical results of self-consistent bandstructure calculations. The presentation starts with an introduction to the modern many-body theory of electronic bandstructure. The essentials of the representation with a non-orthogonal basis and the usual tight-binding variants are...