  Radial elastic corrugation of multiwalled carbon nanotubes under hydrostatic
pressure is demonstrated by using the continuum elastic theory. Various
corrugation patterns are observed under a pressure of several GPa, wherein the
stable cross-sectional shape depends on the innermost tube diameter D and the
total number N of concentric walls. A phase diagram is established to obtain
the requisite values of D and N for a desired corrugation pattern among
choices. In all corrugation patterns, the cylindrical symmetry of the innermost
tube is maintained even under high external pressure.
