Ab initio Simulations of Fe and TiC clusters

Abstract

Iron clusters of bcc, fcc and icosahedral structure, up to the largest Fe₅₉ (bcc), Fe₅₅ and Fe₆₂ (atom- and interstitial-centered fcc), Fe₅₅ (icosahedral), and titanium carbide (Ti₄ C₄, Ti₁₄ C₁₃) were relaxed, within the given morphology type, on the basis of first-principles calculation in the density functional theory, using norm-conserving pseudopotentials and a basis set of strictly localized numerical functions. For TiC, moreover, the vibrational spectrum has been studied in a molecular dynamics approach. The results show inward relaxation at the cluster surface, accompanied by the enhancement of local magnetic moments in several surface layers up to ∼3 μ_B (in Fe), or by hardening of the Γ-TO phonon mode (in TiC).

Keywords:

• Clusters
• Molecular dynamics
• Density functional theory
• Relaxation

Acknowledgements

This work has been supported by the DFG-Sonderforschungsbereich 445 “Nano-partikel aus der Gasphase: Entstehung, Struktur, Eigenschaften”. A.V.P appreciates useful discussions with J. Solér and R. Meyer.