Alouani {\it et al.} Reply to Comment on Tuning of the CDW in MX Chains

TL;DR

This paper clarifies that harmonic elastic models are inadequate for large amplitude charge-density waves in MX chains and emphasizes the importance of anharmonic potentials for accurate modeling.

Contribution

It demonstrates the necessity of anharmonic elastic potentials to correctly describe large amplitude CDWs in MX systems, correcting prior harmonic-based approaches.

Findings

Harmonic elastic energy fits only small dimerization regions.

Anharmonic potentials are essential for modeling large amplitude CDWs.

Harmonic models are insufficient for describing the main physics of MX systems.

Abstract

This is a reply to J. T. Gammel's Comment (9404047) on Tuning of the CDW in MX Chains. We show that while the harmonic elastic energy can fit a small region around zero dimerization, it is insufficient to treat the large amplitude CDW of the MX systems which was the main physics of our Letter (Phys. Rev. Lett. {\bf 71}, 1415 (1993)). We also stress that \underline{anharmonic} elastic potentials are {\it essential} to explain the charge-density-wave systematics of an entire class of MX material.