These constants form the elements of the stiffness matrix in tensor notation, which relates stress to strain through linear equations in anisotropic materials.
Commonly denoted as Cijkl, where i,j,k, and l are the coordinate directions, these constants are essential for understanding how materials deform under various loads.
[3] Specifying how stress and strain are to be measured, including directions, allows for many types of elastic moduli to be defined.
Density functional theory (DFT) provides reliable methods for determining several forms of elastic moduli that characterise distinct features of a material's reaction to mechanical stresses.Utilize DFT software such as VASP, Quantum ESPRESSO, or ABINIT.
Overall, conduct tests to ensure that results are independent of computational parameters such as the density of the k-point mesh, the plane-wave cutoff energy, and the size of the simulation cell.