Phenomenological potentials for the refractory metals Cr, Mo and W

Area of Science:

• Materials Science
• Condensed Matter Physics
• Computational Materials Science

Background:

• Accurate modeling of cohesion in refractory metals is crucial for understanding their mechanical and thermodynamic properties.
• Existing empirical models often struggle to simultaneously predict properties of both perfect and defective crystal structures.

Purpose of the Study:

• To develop and validate a physically motivated n-body energy functional for describing cohesion in Cr, Mo, and W.
• To assess the model's accuracy in predicting thermodynamic properties, phonon dispersion, and defect energetics.

Main Methods:

• Developed a novel n-body energy functional incorporating hard-core repulsion, Thomas-Fermi kinetic energy, and s- and d-valence electron contributions.
• Optimized model parameters against experimental data for perfect and defective crystals.
• Employed lattice dynamics, molecular statics, and molecular dynamics simulations.

Main Results:

• The proposed functional accurately reproduces experimental thermodynamic properties of Cr, Mo, and W.
• Predictions for phonon dispersion relations show good agreement with experimental data.
• Calculations of surface and point defect energetics align well with experimental findings, outperforming other empirical methods.

Conclusions:

• The developed energy functional provides a robust and accurate description of cohesion in refractory metals.
• The model's success in predicting diverse properties makes it suitable for large-scale simulations where direct total energy calculations are prohibitive.