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Seminário de Mecânica Estatística

O seminário de Mecânica Estatística será apresentado na próxima segunda-feira, 01/09/2014, às 11:00h, na sala A5-01 do Instituto de Física.

Título: Global response of sudden changes in the interface growth dynamics

Apresentador: Thiago Albuquerque de Assis (UFBA - UFF)

Resumo: The global effects of sudden changes in the interface growth dynamics
are studied using models of the Edwards-Wilkinson (EW), Kardar-Parisi-Zhang
(KPZ) and Villain-Lai-Das Sarma (VLDS) classes during their growth regimes in
dimensions d=1 and d=2. Scaling arguments and simulation results are
combined to predict the relaxation of the difference in the roughness of the
perturbed and the unperturbed interfaces, \Delta W^2 ~ s^c t^{-\gamma}, where
s is the time of the change and t>s is the observation time after that event..
The previous analytical solution for the EW-EW changes is reviewed and
numerically discussed in the context of lattice models, with possible decays
with \gamma=3/2 and \gamma=1/2. Assuming the dominant contribution to
\Delta W^2 to be predicted from a time shift in the final growth dynamics, the
scaling of KPZ-KPZ changes with \gamma = 1-2\beta and c=2\beta is predicted,
where \beta is the growth exponent. Good agreement with simulation results in
d=1 and d=2 is observed. A relation with the relaxation of a local autoresponse
function in d=1 cannot be discarded, but very different exponents are shown in
d=2. We also consider changes between different dynamics, considering the
KPZ-EW and KPZ-VLDS changes in which a faster growth, with dynamical exponent
z_i, changes to a slower one, with exponent z. For KPZ-EW case, a scaling
approach predicts a crossover time t_c ~ s^{z/z_i} >> s and
\Delta W^2 ~ s^c F(t/t_c), with the decay exponent \gamma=1/2 of the EW class.
This rules out the simplified time shift hypothesis in d=2 dimensions. These
results help to understand the remarkable differences in EW smoothing of
correlated and uncorrelated surfaces. Finally, we verify that the approach may
be extended to discuss the results for KPZ-VLDS case that may be viewed as a
potential application.