On April 21, 2016 Dr. Giuseppe Fadda gave the lecture “Ab initio calculations of elastic properties of crystalline solids: theory and practice” at Samara Center for Theoretical Materials Science.Dr. Giuseppe Fadda is an expert in mathematical modeling methods in materials science. He teaches and carries out research at the Faculty of Mathematics of the University of Padua (Italy) and Samara Center for Theoretical Materials Science.
The lecture was dedicated to theoretical study of elastic properties of materials. Dr. Fadda presented the theory underlying elastic properties study and the main methods of their calculation applying several software packages of quantum-mechanical modeling such as VASP, Crystal, Quantum Espresso and others. He also demonstrated with the examples how to calculate mechanical properties of materials, indicated equations describing them and problems which may arise with different types of materials.
Research of elastic properties of materials is the research of deformation. The more action force, the more compression of a structure. When the action force eases or terminates, the structure restores. The main arguable point is when the structure stops restoring to the initial form and irreversible processes begin, otherwise, where linear theory is not applicable anymore and nonlinear terms come into effect. It’s easier to operate with solids as all equations describe them quite well; a classical example – a diamond - confirms this. Soft materials, possessing small elastic and stiffness coefficients, bring difficulties to researchers. Such materials require using special calculation methods. Choosing equations, researchers should consider under which conditions a structure is, in order to obtain correct results.
Currently, solid state physics describes and calculates the properties of solid materials successfully, but soft materials create complications. That’s why present-day programs operate in automatic mode properly only with solid materials, soft materials are to be calculated in manual or semi-manual mode.
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