No abstract

No abstract

A new efficient photoelectrochemical cell (PEC) is one of the possible solutions to the energy and climate problems of our time. Such a device requires development of new semiconducting materials with tailored properties with respect to stability and light absorption. Here we perform computational screening of around 19 000 oxides, oxynitrides, oxysulfides, oxyfluorides, and oxyfluoronitrides in the cubic perovskite structure with PEC applications in mind. We address three main applications: light absorbers for one-and two-photon water splitting and high-stability transparent shields to protect against corrosion. We end up with 20, 12, and 15 different combinations of oxides, oxynitrides and oxyfluorides, respectively, inviting further experimental investigation.

The ongoing growth in computing power enables researchers to perform such a large number of simulations that cannot be analyzed with paper and pencil any more. Simple approaches of processing data: ordering the calculations in directories and using a script to create a spreadsheet or a small database have to be redesigned for every new project. Sharing intermediate data with collaborators can be cumbersome and when publishing on the Internet specially tailored infrastructure has to be set up.Due to the diverse and changing landscape of electronic structure codes and methods there is no unique way of storing, collecting and presenting results. However there are many partial solutions: VMDF (paper D) a tool to filter and analyze aggregated sets of electronic structure data presents a first step towards user-friendly analysis of data. The Inorganic Crystal Structure Database ICSD [1, 2], collects very specific data and makes it accessible through a web interface; AflowLib (Ab-initio Electronic Structure Library) [3] provides access to structure properties of many compounds on the Internet.What is missing is a system that is Open Source Software, generic enough to support different codes, different abstraction levels and enables users to analyze their own results, and allows to share data with collaborators.The approach of the Computational Materials Repository (CMR) is to convert data to an internal format that maintains the original variable names without insisting on any semantics. Imported data can be implicitly grouped by user criteria and therefore maintain their natural connection in the database as well. Automatic data analysis is enabled through agents that analyze and group data based on predefined rules. Small projects can be handled without the need of database software while bigger projects one can use to improve performance.ii CMR enables one to create templates for the collection and analysis of data independently of the electronic structure code, simplifies screenings involving a lot of calculations, allows one to perform automatic analysis of data based on taxonomy, tags and keywords, provides the ability to share data with collaborators and maintains the link from the derived to the original data. ResuméDen igangvaerende vaekst i computerkraft gør det muligt for forskere at udføre et såstort antal simuleringer, at det ikke laengere er muligt at analysere med papir og blyant. Enkle tilgange til behandling af data: samling af beregninger i mapper og brug af et script til at generere et regneark eller en lille database måredesignes for hvert nyt projekt. Deling af intermediaer data med samarbejdspartnere kan vaere besvaerligt og ved publikation påinternettet skal specifikt skraeddersyede infrastrukturer opsaettes.Grundet det mangeartede og foranderlige landskab af koder og metoder til elektronstruktur-beregninger findes ingen unik måde at gemme, samle og praesentere resultater på. Der findes imidlertid mange delvise løsninger: VMDF (paper D) er et vaerktøj til filtrering og analyse af aggreger...

We present a computational screening study of ternary metal borohydrides for reversible hydrogen storage based on density functional theory. We investigate the stability and decomposition of alloys containing 1 alkali metal atom, Li, Na, or K ͑M 1 ͒; and 1 alkali, alkaline earth or 3d / 4d transition metal atom ͑M 2 ͒ plus two to five ͑BH 4 ͒ − groups, i.e., M 1 M 2 ͑BH 4 ͒ 2-5 , using a number of model structures with trigonal, tetrahedral, octahedral, and free coordination of the metal borohydride complexes. Of the over 700 investigated structures, about 20 were predicted to form potentially stable alloys with promising decomposition energies. The M 1 ͑Al/ Mn/ Fe͒͑BH 4 ͒ 4 , ͑Li/ Na͒Zn͑BH 4 ͒ 3 , and ͑Na/ K͒͑Ni/ Co͒͑BH 4 ͒ 3 alloys are found to be the most promising, followed by selected M 1 ͑Nb/ Rh͒͑BH 4 ͒ 4 alloys.

No abstract

No abstract