Lattice Dynamics and Melting of a
Nonequilibrium Pattern
Abstract:
We present a new description of nonequilibrium square
patterns as a harmonically coupled crystal lattice. In a
vertically oscillating granular layer, different transverse
normal modes of the granular square-lattice pattern are observed
for different driving frequencies (fd) and
accelerations. The amplitude of a mode can be further
excited by either frequency modulation of fd
or reduction of friction between the grains and the plate.
When the mode amplitude becomes large, the lattice melts
(disorders), in accord with the Lindemann criterion for melting
in two dimensions.
Phys. Rev. Lett. 90,
104302 (2003).
Manuscript available in PDF and PS formats.