The Materials Project crystal structure database has been searched for materials possessing layered motifs in their crystal structures using a topology-scaling algorithm. The algorithm identifies and measures the sizes of bonded atomic clusters in a structure's unit cell, and determines their scaling with cell size. The search yielded 826 stable layered materials that are considered as candidates for the formation of two-dimensional monolayers via exfoliation. Density-functional theory was used to calculate the exfoliation energy of each material and 680 monolayers emerge with exfoliation energies below those of already-existent two-dimensional materials. The crystal structures of these two-dimensional materials provide templates for future theoretical searches of stable twodimensional materials. The optimized structures and other calculated data for all 826 monolayers are provided at https://materialsweb.org.The combination of modern computational tools and the growing number of available crystal structure databases with high-throughput interfaces have accelerated recent efforts to map the materials genome. One of the most recently discovered branches of the materials genome is the class of two-dimensional (2D) materials, which generally have properties that are markedly different from their three-dimensional counterparts. The canonical example is the graphite/graphene system, but monolayers have been exfoliated from many other layered compounds as well [1][2][3][4]. Stable 2D materials can also be obtained by deposition [5][6][7][8] or chemical exfoliation [9,10]. Because the contribution of interlayer interactions to these materials free energies is typically quite small, the existence of a mechanically exfoliable bulk precursor generally indicates the relative stability of a freestanding single layer, regardless of how it is synthesized.In an effort to discover novel 2D materials, two recent studies searched the inorganic crystal structure database (ICSD) for compounds with large interlayer spacings, which are characteristic of weak interlayer bonding that could be overcome by mechanical exfoliation [11,12]. They used the intuitive criteria of a low packing fraction based on the covalent radii of the atoms and an interlayer gap larger than the sum of the covalent radii of atoms at the layers' surfaces along the c-axis to identify layered compounds in the ICSD. They discovered almost 100 layered phases, nearly half of which had monolayers that had not been the subject of any prior publications.Here, we extend their method to identify a large number of layered compounds that were missed using the packing factor and c-axis interlayer gap criteria. We further add the constraint that a bulk material must be thermodynamically stable to be of interest during our search. Therefore, we use the Materials Project (MP) database [13], an online repository of crystallographic and thermodynamic data for over 65,000 compounds calculated with density-functional theory (DFT). Our algorithm is designed to correctly identify ad...

The discovery of two-dimensional (2D) materials comes at a time when computational methods are mature and can predict novel 2D materials, characterize their properties, and guide the design of 2D materials for applications. This article reviews the recent progress in computational approaches for 2D materials research. We discuss the computational techniques and provide an overview of the ongoing research in the field. We begin with an overview of known 2D materials, common computational methods, and available cyber infrastructures. We then move onto the discovery of novel 2D materials, discussing the stability criteria for 2D materials, computational methods for structure prediction, and interactions of monolayers with electrochemical and gaseous environments. Next, we describe the computational characterization of the 2D materials' electronic, optical, magnetic, and superconducting properties and the response of the properties under applied mechanical strain and electrical fields. From there, we move on to discuss the structure and properties of defects in 2D materials, and describe methods for 2D materials device simulations. We conclude by providing an outlook on the needs and challenges for future developments in the field of computational research for 2D materials.

To fully leverage the power of image simulation to corroborate and explain patterns and structures in atomic resolution microscopy, an initial correspondence between the simulation and experimental image must be established at the outset of further high accuracy simulations or calculations. Furthermore, if simulation is to be used in context of highly automated processes or high‐throughput optimization, the process of finding this correspondence itself must be automated. In this work, “ingrained,” an open‐source automation framework which solves for this correspondence and fuses atomic resolution image simulations into the experimental images to which they correspond, is introduced. Herein, the overall “ingrained” workflow, focusing on its application to interface structure approximations, and the development of an experimentally rationalized forward model for scanning tunneling microscopy simulation are described.

The discovery of substrate materials has been dominated by trial and error, opening the opportunity for a systematic search. We generate bonding networks for materials from the Materials Project and systematically break up to three bonds in the networks for three-dimensional crystals. Successful cleavage reduces the bonding network to two periodic dimensions. We identify 4693 symmetrically unique cleavage surfaces across 2133 bulk crystals, 4626 of which have a maximum Miller index of one. We characterize the likelihood of cleavage by creating monolayers of these surfaces and calculating their thermodynamic stability using density functional theory to discover 3991 potential substrates. Following, we identify distinct trends in the work of cleavage and relate them to bonding in the three-dimensional precursor. We illustrate the potential impact of the substrate database by identifying several improved epitaxial substrates for the transparent conductor BaSnO3. The open-source databases of predicted and commercial substrates are available at MaterialsWeb.org.