32 speakers and participants took part in the Psi-k, CCP-magnetism and CECAM financed Workshop on the subject of Ab Initio Spin Modelling, which was held at CECAM-HQ, Lausanne, between 26—28 November 2018. The format of the event was designed to foster discussion between groups working on diverse problems in the ab initio treatment of magnetism in solids. Talks of approximately one hour by the invited speakers were interspaced with much lively and enjoyable discussion. The long talks were intended to allow detailed, in depth presentations and this was indeed the outcome. The speakers represented work in quite different methods with electronic structure (e.g., from fully relativistic KKR to perturbation theory based on pseudopotentials/plane waves) – this seemed, if anything, to motivate and promote questions and active involvement by all the participants. Productive discussion also took place during the poster sessions where the quality of the poster presentations was extremely high.
The Psi-k sponsored “CAMD Summer School 2018 Electronic Structure Theory and Materials Design” took place in the week August 12-17, 2018 at Strandhotel Marienlyst in Helsingør, Denmark. Thanks to the more than 100 external attentive summer school students and the 15 very helpful invited lecturers, the school was the nice success that we had hoped for. The school taught PhD students from all over the world the basic and more advanced concepts in modern electronic structure theory including ground state density functional theory (DFT), many-body methods materials informatics and machine learning. Emphasis was put on the methodology applied “on-top” of ab-initio calculations which is essential for the computational design of new functional materials.
Organizers: J. K. Dewhurst, E. K. U. Gross, and S. Sharma
The Psi-k funded Elk-code tutorial took place at the Max Planck Institute of Microstructure Physics (MPI-Halle) in Halle, Germany, from September 3 – 7, 2018. There were a total of 14 speakers and tutors of the code and 45 students from 16 countries. We were oversubscribed and ,unfortunately, had to turn down several applicants (we received in total 61 requests for attending the Elk-tutorials).
The Elk LAPW
code (http://elk.sourceforge.net/) is an electronic structure code based on the state-of-the-art
full-potential linearized augmented plane-wave (LAPW)
method. It was designed from the start to be a user- and
developer-friendly code, allowing PhD students and post-docs to both use the code for their research as well as implement new ideas in the field of electronic structure.
The present Elk-tutorial was fourth in the series of tutorials. The previous tutorials were held in 2011, 2013 and 2015. The aims of the tutorials have been introduction to the ELK code as well as the cutting edge science and implementations in the field of electronic structure methods.
September 25, 2017 – September 29, 2017
Hotel Promenade, Montesilvano, Pescara (Italy)
Silvia Picozzi (Consiglio Nazionale delle Ricerche CNR-SPIN, Italy)
Stefan Blügel (Forschungszentrum Jülich, Germany)
Ingrid Mertig (Martin Luther University Halle, Germany)
The main purpose of this Psi-k/CECAM research conference (with about 110 participants) has been to highlight the very recent theoretical and computational developments related to the interplay of spin-orbit interaction with electronic structure, magnetism, transport as well as its link to strongly correlated materials and ultrafast currents in diverse materials. We have focused on discussing spin-orbit coupling (SOC) as a means of engendering fundamentally novel physical phenomena in exotic systems. The Conference therefore spanned several research dimensions, ranging from Materials (in the form of bulk compounds, surfaces and interfaces, thin films and heterostructures) to Functionalities (associated with topology, spin-momentum locking, valley degrees of freedom, skyrmions, coupling to electric currents by Berry phases, etc.) to method developments (in terms of dynamical processes in out-of-equilibrium quantum matter, Berry phase physics, etc). A brainstorm about concepts and ideas in a little understood phenomenon, such as orbital magnetization, was carried out under the guidance of Prof. Ivo Souza. While the main focus was on ab initio simulations, a few leading scientists in experiments were invited (Prof. Stuart Parkin, Prof. Claudia Felser, etc) and a strong interface to many-body physics treated on the basis of realistic model Hamiltonians was included.
Title: Emerging Technologies in Scientific Data Visualisation Location: CECAM-IT-SISSA-SNS Node, in Scuola Normale Superiore (Pisa, Italy) Webpage with list of participants, schedule and abstracts of presentations:https://www.cecam.org/workshop-1586.html
Dates: April 4, 2018 to April 6, 2018 Organizers:
Stefano de Gironcoli (International School for Advanced Studies (SISSA) and CNR-DEMOCRITOS IOM, Trieste, Italy)
Visualisation allows us to tap into high-bandwidth cognitive hierarchies of our brains and allows us to process high densities of information at once. In the field of atomistic and molecular simulations, it is a key element to research: we use ball-and-stick figures to represent the simulation scenarios, graphs to recognize or communicate parametric relationships of equations. The “Big Data” trend gave rise to several projects with vast output of data, many data-driven approaches are being introduced. For instance, a new EU Center of Excellence, “NOMAD”, is established to collect, store and regularize data to build a materials encyclopedia. Continue reading Report on CECAM Workshop: “Emerging Technologies in Scientific Data Visualisation”.→
This workshop held July 9 to 11, 2018, focused on methods that leverage localized, numeric atom-centered orbital (NAO) basis functions, a choice upon which a number of the strongest available electronic structure developments are founded. The workshop brought together key players from the FHI-aims code and related European and international efforts to highlight, discuss, and advance the state of the art of NAO-based modeling of molecules and materials based on the first principles of quantum mechanics. This workshop covered three days and 23 invited talks, covering:
development of community-based, shared infrastructure projects for electronic structure theory (Garcia, Larsen, Pouillon),
benchmarking efforts to assess and improve the accuracy of approximations used in electronic structure theory (Al-Hamdani, Goedecker, Liu),
applications of density functional perturbation theory (Laasner, Raimbault, Shang),
automation of workflow via machine learning and “big data” efforts (Ghiringhelli, Hoja),
scalability towards large systems and exascale computational resources (Huhn, Scheurer, Yu),
numerical algorithms and new methods for NAO-based electronic structure theory (Hermann, Ringe, Rossi), and
extensions beyond standard Kohn-Sham DFT (Golze, Havu, Michelitsch, Oberhofer, Ren)
Organizers: Thomas Frauenheim (Bremen), Peter Déak (Bremen), Klaus Irmscher (Berlin), Susanne Siebentritt (Luxembourg), Joel B. Varley (Livermore, California)
Venue: University of Bremen, Bremen Center for Computational Materials Science (BCCMS), Germany, 8th until 12th of October 2018
Sponsors: University of Bremen (BCCMS), Psi-k, DFG
Defect engineering in micro/optoelectronics and in photovoltaics has immensely profited from electronic structure calculations. In the past two decades, local and semi-local approximations of density functional theory were the workhorses of theoretical studies but, by now, it has become clear that they do not allow a sufficiently accurate and reliable prediction of defect properties in wide band gap materials. While ab initio energy methods for calculating the total energy are struggling with the system sizes necessary for defect modeling, semi-empirical methods using various corrections or hybrid functionals are being applied for the purpose. While the theoretical background of these methods and their relation to each other is by now more or less understood, the transferability of the semi-empirical parameters and the overall predictive power is still unclear. Progress requires further systematic testing and comparison of the various methods, as well as validation against experiments. For that, accurate measurement data on defects are needed on a set of materials, which are structurally or compositionally related. Gallium based semiconductors, like GaN, Ga2O3 and CuInxGa1-xSe(S)2 chalcogenides (CIGS) offer a good possibility for testing theory and are interesting also experimentally due to their versatile applications.
While there are still open defect-related questions in the much studied blue LED-material GaN, very few defects could be positively identified as yet in CIGS solar cell materials, while the research on the potential power semiconductor and UV transparent electrode Ga2O3 has barely started. Following the successful workshops on Gallium Oxide and Related Materials, held in Kyoto (Japan) in 2015, and in Parma (Italy) in 2017, as well as several workshops on chalcogenide photovoltaic materials, e.g., Symposium V at the E-MRS Spring meeting 2016, the CECAM-workshop in Bremen 2018 will focus on bringing together experimentalist interested in gallium oxide and Ga-based chalocgenides with theorists who are active in the field. A friendly and stimulating environment will facilitate discussions, adding impetus to both the development of practically applicable theoretical methods and to progress in the defect engineering of these materials.
Our workshop was held from the 2nd to the 4th of July at the Hotel Jäger von Fall which sits on a peninsula on the Sylvensteinsee, an artificial lake in the Bavarian foothills of the Alps near the Austrian border. This is a very remote location chosen deliberately to allow participants to concentrate fully on the scientific program. Transportation from and to the nearest train station was accomplished with a shuttle-bus courtesy of the Technical University of Munich (TUM), driven by some of the participating TUM members. For the most part the weather was very inviting, inspiring a small number of participants to take a refreshing swim during the breaks, it turns out that the water was very clear but also very, very cold.
The two evenings of the workshop where filled with a poster-session on Monday, held outdoors due to the lovely weather, and a conference dinner, again outdoors, on Tuesday.
The event was supported by Psi-k, the German science foundation (DFG), the international graduate school of science and engineering (IGSSE), as well as the Technical University of Munich.
The Workshop “Theoretical methods in molecular spintronics (TMSpin) was held at the Materials Physics Center of the University of the Basque Country in Donostia-San Sebastian from the 17th to the 20th of September 2018. This workshop welcomed 31 invited speakers and several postgraduate students presenting posters. The event was co-sponsored by Psi-k and the Donostia International Physics Centre (DIPC- http://dipc.ehu.es/).
Molecular spintronics is the study of spin-related phenomena in molecules and atoms and their possible applications for the next generation of data storage and processing devices as well as for the implementation of quantum computers. Electronic structure theory has played a prominent role in molecular spintronics. The comparison of theory and experiments has demonstrated the importance of first-principles calculations, which go beyond model representations of molecular devices as simple “quantum dots” or effective spin Hamiltonians. Nonetheless, standard electronic structure methods based on Density Functional Theory often fail in describing molecular spintronic systems even at a qualitative level. This is because most magnetic phenomena are manifestations of correlation effects, which become extreme at the single molecule scale and which are not captured by standard implementations and approximations of DFT. The goal of TMSpin was to address the question:
“What electronic structure theory to use for molecular spintronics?”
The workshops gathered theoretical physicists and quantum chemists with different areas of expertise. On the one hand there were those researchers that have provided important contributions to the advancement of molecular spintronics since its inception. They were asked to give an overview about the field and moreover to highlight the open questions that to date cannot yet be addressed by theory. On the other hand, the workshop gathered some of the leading researchers in theory and code development, who presented the most recent fundamental and numerical advancements for a number of methods. The organizers promoted an intense discussion to understand whether such methods can be already employed in molecular spintronics. Continue reading Workshop Report: “Theoretical methods in molecular spintronics” (TMSpin)→
Title: Improving the accuracy of ab-initio predictions for materials Location: CECAM-FR-MOSER Webpage with list of participants, schedule and slides of presentations:http://www.cecam.org/workshop-0-1643.html Dates: September 17, 2018 to September 20, 2018 Organizers:Dario Alfè, Michele Casula, David Ceperley, Carlo Pierleoni
State of the art
Improving the accuracy of ab-initio methods for materials means to devise a global strategy which integrates several approaches to provide a robust, controlled and reasonably fast methodology to predict properties of materials from first principle. Kohn-Sham DFT is the present workhorse in the field but its phenomenological character, induced by the approximations in the exchange-correlation functional, limit its transferability and reliability.
A change of paradigm is required to bring the ab-initio methods to a predictive level. The accuracy of XC functional in DFT should be assessed against more fundamental theories and not, as it is often done today, against experiments. This is because the comparison with experiments is often indirect and could be misleading. The emerging more fundamental method for materials is Quantum Monte Carlo because of: 1) its favourable scaling with system size with respect to other Quantum Chemistry methods; 2) its variational character which defines an accuracy scale and allows to progressively improve the results. However QMC being much more demanding in terms of computer resources, and intricate than DFT, a combined approach is still desirable where QMC is used to benchmark DFT approximations for specific systems before performing the production study by DFT.
A different aspect of accuracy is related to size effects: often relevant phenomena occurs at length and time scales beyond the one approachable by first-principle methods. In these cases effective force fields methods can be employed. Machine Learning methods can be used to extract those force fields from training sets provided by ab-initio calculations. Presently DFT-based training sets are used. Improving their accuracy will improve the ultimate accuracy at all scales.
This change of paradigm requires building a community of people with different expertises working in an integrated fashion. This has been the main aim of the workshop.