How to calculate elastic properties with wien2k 18.2?
Answers
Answer:
Elastic properties play a key role in materials science and technology. The elastic tensors at any order are defined by the Taylor expansion of the elastic energy or stress in terms of the applied strain. In this paper, we present ElaStic, a tool which is able to calculate the full second-order elastic stiffness tensor for any crystal structure from ab initio total-energy and/or stress calculations. This tool also provides the elastic compliances tensor and applies the Voigt and Reuss averaging procedure in order to obtain an evaluation of the bulk, shear, and Young moduli as well as the Poisson ratio of poly-crystalline samples. In a first step, the space-group is determined. Then, a set of deformation matrices is selected, and the corresponding structure files are produced. In the next step, total-energy or stress calculations for each deformed structure are performed by a chosen density-functional theory code. The computed energies/stresses are fitted as polynomial functions of the applied strain in order to get derivatives at zero strain. The knowledge of these derivatives allows for the determination of all independent components of the elastic tensor. In this context, the accuracy of the elastic constants critically depends on the polynomial fit. Therefore, we carefully study how the order of the polynomial fit and the deformation range influence the numerical derivatives and propose a new approach to obtain the most reliable results. We have applied ElaStic to representative materials for each crystal system, using total energies and stresses calculated with the full-potential all-electron codes exciting and WIEN2k as well as the pseudopotential code Quantum ESPRESSO.
Explanation:
Explanation:
Hooke's law describes the elastic properties of materials only in the range in which the force and displacement are proportional. ... For relatively small stresses, stress is proportional to strain. For particular expressions of Hooke's law in this form, see bulk modulus; shear modulus; Young's modulus.
The three types of elastic constants are: Modulus of elasticity or Young's modulus (E), Bulk modulus (K) and. Modulus of rigidity or shear modulus (M, C or G).