Anharmonicity Measure for Materials

Abstract

Theoretical frameworks used to qualitatively and quantitatively describe nuclear dynamics in solids are often based on the harmonic approximation. However, this approximation is known to become inaccurate or to break down completely in many modern functional materials. Interestingly, there is no reliable measure to quantify anharmonicity so far. Thus, a systematic classification of materials in terms of anharmonicity and a benchmark of methodologies that may be appropriate for different strengths of anharmonicity is currently impossible. In this work, we derive and discuss a statistical measure that reliably classifies compounds across temperature regimes and material classes by their "degree of anharmonicity". This enables us to distinguish "harmonic" materials, for which anharmonic effects constitute a small perturbation on top of the harmonic approximation, from strongly "anharmonic" materials, for which anharmonic effects become significant or even dominant and the treatment of anharmonicity in terms of perturbation theory is more than questionable. We show that the analysis of this measure in real and reciprocal space is able to shed light on the underlying microscopic mechanisms, even at conditions close to, e.g., phase transitions or defect formation. Eventually, we demonstrate that the developed approach is computationally efficient and enables rapid high-throughput searches by scanning over a set of several hundred binary solids. The results show that strong anharmonic effects beyond the perturbative limit are not only active in complex materials or close to phase transitions, but already at moderate temperatures in simple binary compounds.

17 figures, 2 tables, and 12 pages

References in corpus (22)

• Restoring the density-gradient expansion for exchange in solids and surfaces
• Generalized gradient approximation for solids and their surfaces
• Distribution of phonon lifetime in Brillouin zone
• Lattice dynamics of anharmonic solids from first principles
• Unified theory of thermal transport in crystals and disordered solids
• Self-consistent phonon calculations of lattice dynamical properties in cubic SrTiO${}_3$ with first-principles anharmonic force constants
• Nuclear quantum effects enter the mainstream
• The hiphive package for the extraction of high-order force constants by machine learning
• One-shot calculation of temperature-dependent optical spectra and phonon-induced band-gap renormalization
• First-Principles Lattice Dynamics Method for Strongly Anharmonic Crystals
• Ab initio Green-Kubo Approach for the Thermal Conductivity of Solids
• Temperature Dependence of the Energy Levels of Methylammonium Lead Iodide Perovskite from First Principles
• Microscopic theory and quantum simulation of atomic heat transport
• A nuclear quantum effect with pure anharmonicity and the anomalous thermal expansion of silicon
• Anharmonic stabilization of the high-pressure simple cubic phase of calcium
• Computational prediction of lattice thermal conductivity -- a comparison of molecular dynamics and Boltzmann transport approaches
• Anharmonic Phonon Quasiparticle Theory of Zero-point and Thermal Shifts in Insulators: Heat Capacity, Bulk Modulus, and Thermal Expansion
• Fully Anharmonic, Non-Perturbative Theory of Vibronically Renormalized Electronic Band Structures
• Strong anharmonicity and high thermoelectric efficiency in high temperature SnS from first-principles
• Theory of thermal expansion: Quasi-harmonic approximation and corrections from quasiparticle renormalization
• The Anharmonic Origin of the Giant Thermal Expansion of NaBr
• Effect of phonon anharmonicity on ferroelectricity in EuxBa1-xTiO3

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• First-Principles Phonon Quasiparticle Theory Applied to a Strongly Anharmonic Halide Perovskite
• Equivariant analytical mapping of first principles Hamiltonians to accurate and transferable materials models
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• Progress and Challenges in Ab Initio Simulations of Quantum Nuclei in Weakly Bonded Systems
• Phonon Self-Energy Corrections: To Screen, or Not to Screen
• Ab initio Green-Kubo simulations of heat transport in solids: Method and implementation
• Efficient first-principles methodology for the calculation of the all-phonon inelastic scattering in solids
• Heat flux for semi-local machine-learning potentials
• Mode-coupling theory of lattice dynamics for classical and quantum crystals
• Thermal conductivity of Li${}_3$PS${}_4$ solid electrolytes with ab initio accuracy
• Ab initio Canonical Sampling based on Variational Inference
• Computational protocol to evaluate electron-phonon interactions within density matrix perturbation theory
• Quantum Vibronic Effects on the Excitation Energies of the Nitrogen-Vacancy Center in Diamond
• Quantum vibronic effects on the electronic properties of molecular crystals
• PINK: physical-informed machine learning for lattice thermal conductivity
• Decoding lithium's subtle phase stability with a machine learning force field
• Photoinduced anisotropic lattice dynamic response and domain formation in thermoelectric SnSe
• Anharmonic thermodynamics redefines metastability and parent phases in ferroelectric HfO2