ElATools: A tool for analyzing anisotropic elastic properties of the 2D and 3D materials

We introduce a computational method and a user-friendly code, named ElATools, developed for the analysis of anisotropic elastic properties. ElATools enables facile analysis of the second-order elastic stiffness tensor of two-dimensional (2D) and three-dimensional (3D) crystal systems. It computes and displays the main mechanical properties including the bulk modulus, Young's modulus, shear modulus, p-wave modulus, universal anisotropy index, Chung-Buessem anisotropy index, log-Euclidean anisotropy parameter, Cauchy pressure, Poisson's ratio, and Pugh's ratio, using three averaging schemes of Voigt, Reuss, and Hill. ElATools has a database with more than 13000 elastic stiffness constants for 3D materials available to the user. The program supports output files of the well-known computational codes IRelat, ElaStic, and AELAS. Three types of plotting and visualization tools are integrated to conveniently interface with GNUPLOT, XMGRACE, and view3dscene, offering immediate post-processing of the results. ElATools provides reliable means to investigate the mechanical stability based on the calculation of six (three) eigenvalues of the elastic tensor in 3D (2D) materials. It can efficiently identify anomalous mechanical properties, such as negative linear compressibility, negative Poisson's ratio, and highly-anisotropic elastic modulus in 2D and 3D materials, which are central properties to design and develop high-performance nanoscale electromechanical devices. Four case studies on selected material systems, ZnAu$_2$(CN)$_4$, CrB$_2$, and $\delta$-phosphorene, and a hypothetical set of systems with cubic symmetry are presented to demonstrate the descriptive and predictive capabilities of ElATools.