Using extensive numerical analysis and exact calculations we show that
the relaxation of a classical particle in 1D anharmonic potential lan
dscapes with a leading quartic term follows a lit decay law at all tem
peratures, leading to a logarithmically increasing mean square displac
ement. For leading anharmonic terms of forth x(2n) we find that the as
ymptotic relaxation is consistent with 1/t(phi), where phi = 1/(n - 1)
at all temperatures. We briefly comment on the possible implications
of this result in the study of displacive structural transitions and i
n complex systems.