Electronic-enthalpy functional for finite systems under pressure

TL;DR

This paper introduces an electronic enthalpy functional for simulating finite systems under pressure, enabling direct electronic pressure application without a pressurizing medium, and demonstrates its use on group-IV nanoparticles under shock conditions.

Contribution

It presents a new first-principles method to model pressure effects on finite systems via an electronic enthalpy functional, allowing for more accurate simulations of nanostructures under load.

Findings

Differences in plastic and elastic responses of diamond cages under shock.

Potential for designing nanostructured impact-absorbing materials.

Validation of the method on group-IV nanoparticles.

Abstract

We introduce the notion of electronic enthalpy for first-principles structural and dynamical calculations of finite systems under pressure. An external pressure field is allowed to act directly on the electronic structure of the system studied via the ground-state minimization of the functional $E+PV_{q}$, where $V_{q}$ is the quantum volume enclosed by a charge isosurface. The Hellmann-Feynman theorem applies, and assures that the ionic equations of motion follow an isoenthalpic dynamics. No pressurizing medium is explicitly required, while coatings of environmental ions or ligands can be introduced if chemically relevant. We apply this novel approach to the study of group-IV nanoparticles during a shock wave, highlighting the significant differences inthe plastic or elastic response of the diamond cage under load, and their potential use as novel nanostructured impact-absorbing materials.