Interfacial Coarsening in Epitaxial Growth Models without Slope Selection

We study the dynamics of an epitaxial growth in the presence of interfacial instabilities that induce a pyramidal or mound-type interfacial growth. We develop a collective coordinates method to analytically discuss the coarsening of growing interfaces in the regime when the mounds' slopes increase with time. We calculate the coarsening exponents characterizing the scaling behavior of the mounds' growth.