A comment on "The Computational 2D Materials Database: high-throughput modeling and discovery of atomically thin crystals"

Recently, Sten Haastrup, Mikkel Strange, Mohnish Pandey, Thorsten Deilmann, Per S Schmidt, Nicki F Hinsche, Morten N Gjerding, Daniele Torelli, Peter M Larsen, Anders C Riis-Jensen, Jakob Gath, Karsten W Jacobsen, Jens Jrgen Mortensen, Thomas Olsen and Kristian S Thygesen [2D Mater. 5 (2018) 042002] introduced the Computational 2D Materials Database (C2DB), which organises a variety of structural, thermodynamic, elastic, electronic, magnetic, and optical properties of around 1500 two-dimensional materials distributed over more than 30 different crystal structures. Unfortunately, the work contains serious and fundamental flaws in the field of elasticity and mechanical stability tests what makes it unreliable.