Temperature quench echoes are analyzed in terms of the temperature-tem
perature correlation function in the harmonic approximation, and the r
esulting expressions are compared with molecular dynamics simulations.
The relationship between the time dependence of the echo depth and th
e density of states is demonstrated for harmonic systems. For a protei
n, which has significant anharmonicity, the time dependence is dominat
ed by relaxation effects that originate from dephasing of the periodic
motions. A simple relaxation model is shown to provide a good descrip
tion of the results observed in the simulations. (C) 1995 American Ins
titute of Physics.