Electronic-Entropy-Driven Solid-Solid Phase Transitions in Elemental Metals

Abstract

We compute the thermodynamic phase diagram of seventeen elemental metals with hexagonal close-packed (hcp), face-centered cubic (fcc), and body-centered cubic (bcc) crystal structures using finite-temperature density functional theory. Helmholtz free-energy differences between competing hcp, fcc, and bcc phases are evaluated as functions of electronic temperature up to 7 eV, allowing us to identify solid-solid phase transitions driven by electronic entropy. The systems studied include Zr, Ti, Cd, Zn, Co, and Mg (hcp), Ni, Cu, Ag, Al, Pt, and Pb (fcc), and Cr, W, V, Nb, and Mo (bcc) in their ground-state structures. From the free-energy crossings, we extract the transition electronic temperatures and analyze systematic trends across the metallic systems. We found that all the studied systems go through one or two solid-solid phase transition caused purely by electronic entropy except Mg and Pb. Our results establish electronic entropy as a key factor governing structural stability in metals under strong electronic excitation.

References in corpus (18)

• Quantum ESPRESSO: a modular and open-source software project for quantum simulations of materials
• Restoring the density-gradient expansion for exchange in solids and surfaces
• Generalized gradient approximation for solids and their surfaces
• Phonons and related properties of extended systems from density-functional perturbation theory
• Advanced capabilities for materials modelling with Quantum ESPRESSO
• FPEOS: A First-Principles Equation of State Table of Deuterium for Inertial Confinement Fusion Applications
• Ab initio simulation of warm dense matter
• Ab initio investigation of Elliott-Yafet electron-phonon mechanism in laser-induced ultrafast demagnetization
• The importance of finite-temperature exchange-correlation for warm dense matter calculations
• First-Principles Equation of State Database for Warm Dense Matter Computation
• First principles simulations of dense hydrogen
• First-Principles Equation of State Calculations of Warm Dense Nitrogen
• High Pressure Phase Diagram of Beryllium from \emph{Ab Initio} Free Energy Calculations
• Mapping the Electronic Structure of Warm Dense Nickel via Resonant Inelastic X-ray Scattering
• Finite temperature density functional theory investigation to the nonequilibrium transient warm dense state created by laser excitation
• Shock-driven amorphization and melt in Fe${}_2$O${}_3$
• Phase transitions of Fe${}_2$O${}_3$ under laser shock compression
• Electronic Temperature-Driven Phase Stability and Structural Evolution of Iron at High Pressure

Cited by in corpus (1)

• Electronic-Entropy-Driven Phase Transitions in Compressed Iron Oxides