Measuring similarities/dissimilarities between atomic structures is important for the exploration of potential energy landscapes. However, the cell vectors together with the coordinates of the atoms, which are generally used to describe periodic systems, are quantities not directly suitable as fingerprints to distinguish structures. Based on a characterization of the local environment of all atoms in a cell, we introduce crystal fingerprints that can be calculated easily and define configurational distances between crystalline structures that satisfy the mathematical properties of a metric. This distance between two configurations is a measure of their similarity/dissimilarity and it allows in particular to distinguish structures. The new method can be a useful tool within various energy landscape exploration schemes, such as minima hopping, random search, swarm intelligence algorithms, and high-throughput screenings. C 2016 AIP Publishing LLC. [http://dx

We investigate the accuracy and transferability of a recently developed high dimensional neural network (NN) method for calcium fluoride, fitted to a database of ab initio density functional theory (DFT) calculations based on the Perdew-Burke-Ernzerhof (PBE) exchange correlation functional. We call the method charge equilibration via neural network technique (CENT). Although the fitting database contains only clusters (i.e. non-periodic structures), the NN scheme accurately describes a variety of bulk properties. In contrast to other available empirical methods the CENT potential has a much simpler functional form, nevertheless it correctly reproduces the PBE energetics of various crystalline phases both at ambient and high pressure. Surface energies and structures as well as dynamical properties derived from phonon calculations are also in good agreement with PBE results. Overall, the difference between the values obtained by the CENT potential and the PBE reference values is less than or equal to the difference between the values of local density approximation (LDA) and Born-Mayer-Huggins (BMH) with those calculated by the PBE exchange correlation functional.

Over the last two decades, several classes of highly ion-conductive SSEs have been developed which reach or surpass current liquid-state electrolyte conductivity. [5,6] Yet, no ASSB paying in on the above promises has been developed to date. This is mainly due to mechanochemical, chemical, and electrochemical stability issues and interfacial processes that have severely compromised any proposed cell's lifetime. [7][8][9][10][11] While many SSE material inherent (mechano-)chemical processing issues seem amenable to modern engineering approaches, [12][13][14][15][16][17][18][19] the situation is less bright regarding the control of interfacial chemical and electrochemical stability (especially when featuring a LMA), as well as ionic and electronic transport quantities across these interfaces. A hitherto missing deep understanding of the structural, chemical, and physical properties of the buried solid-solid interfaces inside ASSBs at the atomic level is required to overcome these performance limiting interfacial issues.The most studied interfacial properties so far are contact stability and dendrite nucleation and growth. [20][21][22] Both issues are accentuated for LMA/SSE interfaces. In a first approximation, interfacial stability can be traced back to the Dendrite formation and growth remains a major obstacle toward highperformance all solid-state batteries using Li metal anodes. The ceramic Li (1+x) Al (x) Ti (2−x) (PO 4 ) 3 (LATP) solid-state electrolyte shows a higher than expected stability against electrochemical decomposition despite a bulk electronic conductivity that exceeds a recently postulated threshold for dendrite-free operation. Here, transmission electron microscopy, atom probe tomography, and first-principles based simulations are combined to establish atomistic structural models of glass-amorphous LATP grain boundaries. These models reveal a nanometer-thin complexion layer that encapsulates the crystalline grains. The distinct composition of this complexion constitutes a sizable electronic impedance. Rather than fulfilling macroscopic bulk measures of ionic and electronic conduction, LATP might thus gain the capability to suppress dendrite nucleation by sufficient local separation of charge carriers at the nanoscale.

We report on the ab initio discovery of a novel putative ground state for quasi two-dimensional TiO2 through a structural search using the minima hopping method with an artificial neural network potential. The structure is based on a honeycomb lattice and is energetically lower than the experimentally reported lepidocrocite sheet by 7 meV/atom, and merely 13 meV/atom higher in energy than the ground state rutile bulk structure. According to our calculations, the hexagonal sheet is stable against mechanical stress, it is chemically inert and can be deposited on various substrates without disrupting the structure. Its properties differ significantly from all known TiO2 bulk phases with a large gap of 5.05 eV that can be tuned through strain engineering. arXiv:1704.03983v1 [cond-mat.mtrl-sci]

We report on an extensive study of ZnO materials with cage-like motives in clusters and bulk phases through structural searches using the minima hopping method. A novel putative ground state was discovered for the (ZnO)32 cluster with a tube-like structure, closely related to the previously reported (ZnO)24 ground state cage geometry. Furthermore, the effect of ionization on the geometries and energetic ordering of (ZnO)n clusters with n = 3 − 10, 12 was studied by directly sampling the energy landscape of the ionized system. Our results indicate that the transition from ring and planar structures to 3D cages occurs at larger cluster sizes than in the neutral system. Inspired by the bottom-up design philosophy and the predominance of cage-like structures in medium-sized clusters, a search for crystalline ZnO was conducted aimed specifically at low density polymorphs, resulting in the discovery of 57 novel metastable phases. The voids in these low-density materials closely resemble the hollow cage structures of small (ZnO)n/(ZnO) + n clusters with n < 16. In analogy to clathrate materials, these voids could serve to accommodate guest atoms to tailor the materials properties for various applications.