Supporting Material for: Superionicity and Polymorphism in Calcium Fluoride at High Pressure

TL;DR

This paper provides detailed ab initio calculations and structural analyses of calcium fluoride under high pressure, revealing phase stability, defect energetics, and vibrational properties relevant to superionic behavior.

Contribution

It introduces new computational insights into the high-pressure phases, defect formation, and vibrational spectra of CaF2, expanding understanding of its superionic and polymorphic properties.

Findings

Identification of high-pressure monoclinic phase in CaF2

Computed formation energies of Frenkel defects under pressure

Vibrational spectra supporting phase stability analysis

Abstract

In this supplemental document we explain the details of our ab initio density functional theory calculations and crystal structure searches performed in CaF2 under pressure. Also we report the computed P-dependence of the formation energy of Frenkel pair defects in the cubic fluorite phase, and the vibrational phonon spectra and structural data of the predicted high-T monoclinic P2_1/c phase. Calculated enthalpy energies in compressed SrF2 and BaF2 are also presented.