Second, the typical ‘slab’ approach for performing surface energy calculations requires the use of large supercells with the introduction of a large vacuum region, which makes such calculations computationally intensive, especially for low symmetry materials and high Miller indices. can significantly affect the accuracy and convergence of surface energies, which in turn leads to values that are generally difficult to compare across different works 37. First, the choice of the exchange correlation functional as well as other parameters such as pseudopotentials, integration grid, etc. The challenges for DFT determination of surface properties are three-fold. However, this database is limited to surfaces of ground state crystals up to a maximum Miller index (MMI) of 1 only.
Silver surface energy wulff construction wolfram player full#
35 have previously compiled a database of surface energies for all metals up to Pu using the full charge density (FCD) DFT method, a technique based on the coupling of the linear muffin-tin orbital method and the atomic-sphere approximation 36. Indeed, fundamental and application-driven computational studies of surfaces in the literature are extensive 8, 32– 34. Computational techniques provide the means to precisely control the surface structure and composition. 27 and Keene 28.įirst principles computations such as those based on density functional theory (DFT) methods are important complementary tools to experimental techniques in characterizing surface properties of a material 29– 31. Reviews of such surface tension techniques have been compiled by Mills et al. References 26 and 20 have accumulated a large set of metallic elemental surface energy data by extrapolating surface tension of liquid phases for solid surfaces. Furthermore, experimentally observed Wulff shapes are often inconsistent across studies due to the sensitivity of high energy facets to temperature and impurities 25. Despite its importance, experimental determination of surface energies, especially for specific facets, is difficult and rare 20– 24. This fundamental quantity is important in understanding surface structure, reconstruction, roughening and the crystal’s equilibrium shape 19. The stability of a surface is described by its surface energy γ, a measure of the excess energy of surface atoms due to a variety of factors, such as the broken bonds yielding undercoordinated atoms. For example, the nanoscale stability of metastable polymorphs is determined from the competition between surface and bulk energy of the nanoparticle 15– 18. Surface effects are especially important in nanomaterials, where relatively large surface area to volume ratios lead to properties that differ significantly from the bulk material 10– 14. For instance, technologies such as fuel cells and industrial chemical manufacturing require the use of catalysts to accelerate chemical reactions, which is fundamentally a surface-driven process 1– 9. The surface properties of a crystal are crucial to the understanding and design of materials for many applications. We will describe the methodology used in constructing the database, and how it can be accessed for further studies and design of materials. The database is systematically improvable and has been rigorously validated against previous experimental and computational data where available. Well-known reconstruction schemes are also accounted for. This database contains the surface energies of more than 100 polymorphs of about 70 elements, up to a maximum Miller index of two and three for non-cubic and cubic crystals, respectively. In this work, we present the largest database of calculated surface energies for elemental crystals to date. Such surface phenomena are especially important at the nanoscale, where the large surface area to volume ratios lead to properties that are significantly different from the bulk. The surface energy is a fundamental property of the different facets of a crystal that is crucial to the understanding of various phenomena like surface segregation, roughening, catalytic activity, and the crystal’s equilibrium shape.
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