Moving intrinsic gap mode
Displacements of particles involved in a moving anharmonic gap mode at
three different times. The mode is excited at
T=0, then viewed at
Tm is the vibrational period of
highest frequency plane wave mode.
the odd-parity mode
with the amplitude
is centered at the light particle
(at site number 100) in a diatomic lattice
particles with fixed boundary conditions. The light particles in the
chain are represented by small circles and the heavy ones by squares.
Velocities of particles involved in a moving anharmonic gap mode at
three different times.
The lowest curve corresponds to the maximum velocity of the
odd-parity mode centered at site 100 and the upper curve shows the
odd-parity mode with the maximum velocity centered at site 102. The
middle curve shows an even-parity-mode pattern which takes place at
the intermediate time. At this particular time the particles at
sites 100 and 102 have maximal but opposite velocities. This
illustration demonstrates that as the mode moves through the lattice
it passes sequentially through the displacement patterns of even- and
odd-parity, a result similar to that first observed for an anharmonic
local mode in a simple monatomic lattice with hard quartic potential .
 K. W. Sandusky, J. B. Page and K. E. Schmidt, Phys. Rev. B
46, 6161 (1992).
Last modified: August 10, 1997