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

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.