We study slow collective motion at finite thermal excitations on the basis of
linear response theory applied to the locally harmonic approximation. The
transport coefficients for average motion, friction \gamma, inertia M and the
local stiffness C are computed along a fission path of Th-224 within a
quasi-static picture. The inverse relaxation time \beta=\gamma/M and the
effective damping rate \eta=\gamma/(2\sqrt{M|C|}) are found to increase with
temperature, but do not change much with the collective variable. The values
found for \eta and \beta as well as their behavior with temperature are in
accord with experimental findings.Comment: 23 pages, including figures, Latex plus 11 postscript files for
figures; home page:
http://www.physik.tu-muenchen.de/tumphy/e/T36/hofmann.htm