An efficient pseudo-spectral algorithm for the RPA response of ordered phases of block copolymer melts

We present a pseudo-spectral algorithm for calculating the linear response of monomer concentration field in ordered phases of block copolymer melts to small perturbations of the monomer chemical potential fields. The method is both considerably simpler and more efficient than the fully spectral perturbation theory presented by Laradji, Shi and coworkers.[1] The method will be used to re-examine the stability of the gyroid phase in diblock copolymer melts. \newline \newline [1] Laradji {\em et al.}, {\em Macromolecules}, {\bf 30}, 3242 (1997).