be periodic

References in periodicals archive ?
I want to use this first of what will be periodic Editor's Letters to tell you something about how we will be running the Journal and how you can help/participate in the process, should you be interested.
Be cause the cutting plane is irrational the surface cannot be periodic; it will never go through exactly the same point in two different unit cells.
Although it could not be proven, it was taken as plausible by many eminent scholars that the lowest energy configuration of a set of identical atoms or molecules would be periodic. Similarly it was assumed that the lowest energy configuration of any mixture of atoms or molecules would be a periodic arrangement of identical unit cells forming a stoichiometric compound, or a mixture of such periodic structures.