Reliability evaluation of thermophysical properties from first-principles calculations

Abstract

Thermophysical properties, such as heat capacity, bulk modulus and thermal expansion, are of great importance for many technological applications and are traditionally determined experimentally. With the rapid development of computational methods, however, first-principles computed temperature-dependent data are nowadays accessible. We evaluate various computational realizations of such data in comparison to the experimental scatter. The work is focussed on the impact of different first-principles codes (QUANTUM ESPRESSO and VASP), pseudopotentials (ultrasoft and projector augmented wave) as well as phonon determination methods (linear response and direct force constant method) on these properties. Based on the analysis of data for two pure elements, Cr and Ni, consequences for the reliability of temperature-dependent first-principles data in computational thermodynamics are discussed.

Atomistic Modeling‐Based Design of Novel Materials

“…Density Functional Theory is a ground state theory and, thus, within its original formulation allows accessing materials properties À first of all À at 0 K. However, in particular within the last decade, new methodologies have emerged which advanced DFT simulations to finite temperatures (for more details see, e.g., reviews by Palumbo et al [123] or Baroni et al [124] ). One perquisite in doing so has been the development of computationally efficient methods enabling to perform highly-accurate lattice dynamics simulations.…”

Thermodynamic modelling of crystalline unary phases

“…Vibrational excitations (phonons) provide the main contribution to the thermodynamics of crystalline solid phases. In addition to the increased computational power available, recent progress in theory and computer codes has made it possible to perform calculations of phonon frequencies and related properties for several systems . Phonon frequencies can be computed by either density‐functional perturbation theory (DFPT) () or supercell (or small displacements) approaches .…”

“…Despite its simplicity, the QHA can describe the main anharmonic effects in many systems. However, there are many systems in which this approximation fails and in general at high temperatures it becomes less reliable than other more advanced techniques based on AIMD.…”

Electronic Structure and Magnetic Properties of Graphene/Ni3Mn/Ni(111) Trilayer

“…4(b): the intensity of the d ↓ band is suppressed and the sp ↓ is not present in the spectra. At the same time the intense bands at the Γ point, which can be assigned to the Ni 3d states or to the mixture of the Ni+Mn 3d bands, are shifted from E − E F ≈ −1.4 eV for gr/Ni(111) to E − E F ≈ −1 eV for gr/Ni 3 Mn/Ni(111), respectively [45,46]. All these changes, which clearly demonstrate the occurrence of a new phase (i. e. Ni 3 Mn) as also shown by the structural data and discussed below, have implications on the electronic and transport properties of graphene in this system.…”