Exact block diagonalization of large eigenvalue problems for structures with symmetry

Abstract We consider large eigenvalue problems for skeletal structures with symmetry. We present an algorithm, based upon a novel combination of group‐theoretic ideas and substructuring techniques, that block‐diagonalizes such systems exactly and efficiently. The procedure requires only the structural matrices of a repeating substructure, together with the symmetry modes, which are obtained from symmetry considerations alone. We first present a simple paradigmatic example and then follow with several non‐trivial applications involving large lattice structures.