Slow crossover to Kardar-Parisi-Zhang scaling - art. no. 051101

The Kardar-Parisi-Zhang (KPZ) equation is accepted as a generic description of interfacial growth. In several recent studies, however, values of the r oughness exponent a have been reported that are significantly less than tha t associated with the KPZ equation. A feature common to these studies is th e presence of holes (bubbles and overhangs) in the bulk and an interface th at is smeared out. We study a model of this type in which the density of th e bulk and sharpness of the interface can be adjusted by a single parameter . Through theoretical considerations and the study of a simplified model we determine that the presence of holes does not affect the asymptotic KPZ sc aling. Moreover, based on our numerics, we propose a simple form for the cr ossover to the KPZ regime.