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Ab initio data mining approach has been used in order to investigate B6O system and discover new possible modifications, besides experimentally known R-3m (α-B6O) structure and theoretically predicted Cmcm (β-B6O) structure. DFT calculations were performed by two different functionals, LDA and PBE. In this work, we focus on the structure, mechanical, and electronic properties of the experimentally known α-B6O structure and newly predicted modifications with the B6O stoichiometry. Moreover, mechanical properties including elastic constants, bulk, shear and elastic moduli, Poisson’s ratio, Pugh’s criterion, and hardness are given for the investigated modifications of B6O. In particular, we have investigated the influence of the high pressure on the electronic and mechanical properties. Results of our study provide more insight in the B6O superhard material and open new possibilities for various device applications.

Due to their great importance in science, technology, and the life sciences, water and ice have been extensively investigated over many years. In particular, hexagonal ice Ih has been of great interest since it is the most common form of ice, and several modifications, Ih(a), Ih(b) and Ih(c) are known, whose structural details are still under discussion. In this study, we present an alternative theoretical model, called Ih(d), for the hexagonal ice modification in space group P6 3 /mmc (no. 194), based on first-principles calculations that have been performed using DFT-LDA, GGA-PBE, and hybrid B3LYP and PBE0 functionals.