Stability, Electronic Structure and Vibrational Modes of Ti_8C_12 Dimer

TL;DR

This study uses density functional theory to analyze the stability, electronic structure, and vibrational modes of Ti_8C_12 dimers, revealing their covalent bonding nature and stability under certain conditions.

Contribution

It provides the first detailed computational analysis of Ti_8C_12 dimers, challenging previous views of their stability as monodispersed clusters.

Findings

Ti_8C_12 dimers are covalently bonded and stable.

Dimer formation is influenced by environmental organic ligands.

Vibrational analysis confirms the dynamical stability of the lowest-energy structure.

Abstract

We present our density functional results of the geometry, electronic structure and dissociation energy of Ti_8C_12 dimer. We show that as opposed to the currently held view that Ti_8C_12 are highly stable monodispersed clusters, the neutral Ti_8C_12 clusters form covalent bonds and form stable dimers. We determine that the Ti atoms bond weakly (0.9 eV/bond) to organic ligands such as ammonia. Alternatively the Met-Car dimer has a cohesive energy of 4.84 eV or approximately 1.2 eV per bond. While Met-Car dimers are stable, formation of these dimers may be quenched in an environment that contains a significant population of organic ligands. The ionization and dissociation energies of the dimer are of same order which prevents the observation of the dimer in the ion mass spectroscopy. The analysis of the vibrational frequencies show the lowest-energy structure to be dynamically stable. We also present infrared absorption and Raman scattering spectra of the Ti_8C_12 dimer.