Elastic properties and anisotropic behavior of structure-H (sH) gas hydrate from first principles

Structure-H gas hydrate is recognized by its hexagonal symmetry and anisotropy. The available structure-mechanical properties relations of this hydrate from an atomistic scale are scarce. This work presents the main mechanical properties of sH hydrate addressing its structural anisotropy based on ab initio atomic simulations. The empty metastable and filled sH hydrates of neohexane and different help gases are simulated to establish their mechanical and anisotropic characteristics. Guest molecules increase the stiffness and rigidity of sH hydrate, and they define its anisotropy. The anisotropy of sH hydrate was reflected in its high moduli values along the c-axis as compared to the a-axis. Analyzing sH hydrate response to applied triaxial stress reveals its maximum tensile strength. The hydrogen and the covalent O-H bonds were found to behave in an opposite manner under applied stress. This work contributes to the fundamental understanding and potential technological applications of this less known gas hydrate. (C) 2020 Elsevier Ltd. All rights reserved.