# Anharmonic effects on the dynamical stability of Ce–Co–Cu intermetallic ternary compounds

## TL;DR

This study investigates the stability of Ce–Co–Cu compounds and finds that anharmonic effects stabilize them at high temperatures despite being unstable at low temperatures.

## Contribution

The study reveals the role of anharmonic interactions in stabilizing Ce–Co–Cu compounds at finite temperatures.

## Key findings

- Harmonic phonon calculations predict some Ce–Co–Cu structures are dynamically unstable at 0 K.
- AIMD simulations show these structures are stable at finite temperatures due to anharmonic effects.
- A predicted compound has a double-well potential energy landscape below 200 K.

## Abstract

Ce-based intermetallic compounds are of growing interest for their potential applications in energy-efficient permanent magnets. While recent machine learning and DFT studies predicted several new Ce–Co–Cu ternary compounds to be stable at T = 0 K, their dynamical stability requires further investigation. We show that first-principles harmonic phonon calculations predict imaginary vibrational modes for some structures, suggesting they are dynamically unstable at 0 K. However, ab initio molecular dynamics (AIMD) simulations reveal that these structures are stable at finite temperatures. Vibrational density-of-states and phonon modes calculated at finite temperature through the AIMD simulations suggest that anharmonic interactions are important in stabilizing these predicted Ce–Co–Cu intermetallic compounds.

A predicted Ce–Co–Cu compound shows high-temperature dynamical stability yet exhibits a double-well potential energy landscape below 200 K.