Comment on "Macrospopic Equation for the Roughness of Growing Interfaces in Quenched Disorder"

TL;DR

This paper critiques a recent proposed equation for interface dynamics in quenched disorder, arguing it only describes short-term behavior and does not capture large-scale interface evolution.

Contribution

It provides a clarification that the proposed equation is effective only at short times and offers a new expression for short-time interface behavior applicable across all q values.

Findings

The proposed equation is limited to short-time regimes.

A new expression for short-time behavior is derived.

The equation does not describe macroscopic interface dynamics.

Abstract

We comment on a recent Letter by Braunstein and Buceta [PRL vol.81, 630 (1998)], in which a novel equation has been proposed to describe the dynamics of interfaces in the presence of quenched disorder. We argue that the ansatz Braunstein and Buceta presented is just an effective description of the very short times regime and has no significance for the macroscopic (large scale) behaviour of the interface. We calculate an expression for the short time behaviour of the interface that is valid for any q (and not only at q_c).