Highlights

A new study by Philipp Werner's group at the University of Fribourg makes advancements in the theoretical description of the correlated electron state of La3Ni2O7,  which has recently been described as a superconductor with a critical temperature around 80 K. The use of  GW+EDMFT, a method developed within MARVEL over the last ten years, was crucial for the study.

Scientists from NCCR MARVEL led the most comprehensive verification effort so far on computer codes for materials simulations, providing their colleagues with a reference dataset and a set of guidelines for assessing and improving existing and future codes.

Two newly-released articles by MARVEL members Junfeng Qiao, Giovanni Pizzi and Nicola Marzari provide scientists with very robust and reliable algorithms that standardize and automatize the process of obtaining  Wannier functions for a given material, a much used tool for computational condensed matter physics and materials science.  To validate their algorithms, the scientists first chose four or five typical materials to explain how the methods work and reproduce what chemists would already guess about the materials. Then they stress-tested these algorithms on a larger set of materials to collect statistics and compare to previous approaches.

Scientists have been looking for real-world examples of Weyl semi-metals, that are topological materials with unique transport, optical and thermoelectric behavior. Many computational and experimental papers had described a compound of europium, cadmium and arsenic, EuCd2As2, as a Weyl semi-metal. But a new study just published by an international research team led by MARVEL’s Ana Akrap has found that it is instead a magnetic semiconductor.

A 10-year effort has led to a theoretical framework and a software package, called koopmans, that allows to obtain reliable spectral properties of molecules and materials with density functional theory. The framework is described in a new article by MARVEL researchers at EPFL, and last month a week-long school co-organised by MARVEL in Pavia saw students learning about Koopmans functionals and trying out the code.

A research group including MARVEL scientists has developed, studied computationally and tested a transistor based on strips of graphene with widths of only a few nanometers, thanks to a new fabrication technique that overcomes the current challenges in making electrical contacts between graphene nanoribbons and electrodes.  

EPFL researchers make theoretical breakthrough in thermoelectric material to better harness waste heat for sustainable energy.

The collection of 2D materials, first initiated  in 2018, has been expanded with 1,252 new monolayers that could be exfoliated from existing tridimensional structures.

A new study by Berend Smit’s group at EPFL introduces a new computational framework that allows to screen large numbers of Covalent Organic Frameworks (COFs) in a fast and efficient way, to pre-select the best candidates for specific photocatalytic applications, such as water splitting. Starting from a set of 419 COFs for which there are reported experiments, the workflow allowed the selection of 13 candidate materials for water splitting. 

Quantum computing holds great promises for computational material science. A new project added to NCCR MARVEL at the beginning of Phase III wants to explore the potential of the current generation of hybrid systems - that combine a classical machine with a quantum one – for the simulation of electronic structures. Project leader Giuseppe Carleo explains how the group will develop new algorithms and novel machine learning strategies to run on these machines and improve the accuracy of current modelling methods. “The classical part does the heavy lifting and brings you very close to the exact solution," he explains, "and then you hope the quantum part gives you the extra step to reach the final accuracy".

A new method developed by the NCCR MARVEL laboratory of Michele Ceriotti at EPFL allows modelling alloys containing up to 25 transition metals, matching a remarkable accuracy with a manageable requirement of data and computational resources. The group validated the model and used it for computational experiments on three representative alloy compositions. In the future the model will be expanded to predict the catalytic behaviour of the surfaces of high-entropy alloys.

NCCR MARVEL researchers have applied DFT with extended Hubbard functionals (DFT+U+V) to the study of two candidate cathode materials belonging to the class of lithium-manganese-oxide spinels. They used a new approach to determine the Hubbard U and V parameters entirely from first principles and found that the method accurately predicts the geometrical properties, oxidation states, band gaps, and voltages of the two materials. The article was included in the "2023 PCCP HOT Articles" collection.