Engineering microporous architectures: combining evolutionary algorithms with predefined exclusion zones

Abstract

A global optimisation technique, based on the principles of evolution, has been refined for the prediction of plausible crystal framework structures from the knowledge of only the unit cell dimensions, constituent atoms and by defining exclusion zones--regions within the unit cell, from where the constituent atoms are repelled. The technique developed can be applied generally in generating new feasible framework structures with predefined microporous architectures. During the search, all trial, or candidate, structures are immediately relaxed by minimising the internal energy, which is based on the Born, or rigid ion, model of a solid. We present details of the implementation within the computational package GULP. Application to generating various microporous silicate framework structures, without imposing any symmetry constraints on the ionic positions, is described.