High pressure and temperature thermoelasticity of hcp osmium from ab initio quasi-harmonic theory

Abstract

We present a systematic ab initio study of the thermoelastic properties of hcp osmium as functions of temperature and pressure within the quasi-harmonic approximation (QHA). The precision of the Zero Static Internal Stress Approximation (ZSISA) and of the volume-constrained ZSISA (V-ZSISA) are rigorously assessed. For osmium, we find negligible deviations between ZSISA and a full free energy minimization (FFEM) approach. Also, the V-ZSISA approximation influences the results very little, as we found already in beryllium, despite the markedly different behavior of the c/a ratio with temperature in the two metals. Our QHA-derived ECs show excellent agreement with available experimental data in the temperature range of 5-301 K, outperforming the results obtained from the quasi-static approximation (QSA). Additionally, we report the pressure-dependent QHA ECs at 5 K, 301 K, and 1000 K, spanning pressures from 0 to 150 kbar.

9 pages, 11 figures, 2 tables

References in corpus (12)

• 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
• Advanced capabilities for materials modelling with Quantum ESPRESSO
• Potential super-hard Osmium di-nitride with fluorite structure: First-principles calculations
• Quasi-harmonic temperature dependent elastic constants: applications to silicon, aluminum, and silver
• Quasi-harmonic thermoelasticity of palladium, platinum, copper, and gold from first principles
• Temperature dependent elastic constants and thermodynamic properties of BAs: an ab-initio investigation
• Lifshitz transitions and elastic properties of Osmium under pressure
• Ab initio quasi-harmonic thermoelasticity of molybdenum at high temperature and pressure
• High temperature and pressure thermoelasticity of hcp metals from ab initio quasi-harmonic free energy calculations: the beryllium case
• An alternative GPU acceleration for a pseudopotential plane-waves density functional theory code with applications to metallic systems