Category Archives: Reports

ETSF-19th Young Researchers’ Meeting

The Young Researchers’ Meeting (YRM) of the European Theoretical Spectroscopy Facility (ETSF) is an annual event that brings together young researchers working on theoretical and computational approaches for studying the electronic and optical properties of materials. It is specifically aimed at MSc and Ph.D. students, as well as postdoctoral researchers. In other words, researchers who have not obtained yet a permanent position are eligible to attend, exchange, and present their research work. Over the years, the focus of the YRM has expanded beyond theoretical spectroscopy to include various other fields such as transport, magnetism, spintronics, correlated systems, and multiscale modelling, and more recently, in the current edition, we also included a session fully dedicated to quantum computing. The objective of the meeting is to provide a platform for young researchers to present their work, learn about state-of-the-art theoretical methods in their field and provide insights into related fields to help the ETSF community to grow further and expand their scope with ideas from different geographical areas and research orientations. Continue reading ETSF-19th Young Researchers’ Meeting

Ab initio many-body perturbation theory: from equilibrium to time-resolved spectroscopies and nonlinear optics

The school, themed “Ab initio many-body perturbation theory: from equilibrium to time-resolved spectroscopies and nonlinear optics,” took place from May 22nd to May 26th, 2023. The event took place in the captivating setting of Argiletum, located at the heart of Rome’s city centre.  The school was made possible through the sponsorship of the MaX Centre of Excellence — Materials Design at Exascale–, the Italian Cecam-IIT Simul node, and the Psi-k network. It brought together 39 participants from various countries, representing a diverse and inclusive community. The aim of the school was to provide comprehensive training on theoretical and computational methods, with a specific focus on the YAMBO code and its recent advancements. Continue reading Ab initio many-body perturbation theory: from equilibrium to time-resolved spectroscopies and nonlinear optics

Conference on Defects in Solids for Quantum Technologies (DSQT2022)

From the 12th to 17th of June 2022, the conference on defects in solids for quantum technologies was held in Stockholm, Sweden, at the AlbaNova University Center of Stockholm University. The final scientific program of the conference lasted for five full days, included 34 invited talks, 48 contributed talks, and a poster session with 30 posters, all-in-all having 119 participants from 21 countries. The event was sponsored jointly by the Psi-k organization and  CECAM, and partly funded by the organizing universities of Linköping University and Stockholm University with funds from the Knut and Alice Wallenberg Foundation.

The conference covered the state-of-the-art advances in the study of defects in semiconductors and the quantum properties they exhibit which are favorable for applications in future information, communication, and sensing technology. Considerable effort has been spent to develop a basic unit of quantum information processing (or qubit) from different individual quantum systems, such as single atoms or ions trapped in a crystal lattice, single Josephson superconducting devices, single photons emitted from quantum dots or single photons/spins associated with point defects in semiconductors. Quantum states due to point defect in wide band gap semiconductors may realize single photon sources and quantum bits that can be harnessed in quantum information processing and nanoscale sensor applications at room temperature. The leading contender is the nitrogen-vacancy center in diamond that may be considered as a robust quantum bit. However, the possibility to realize bright single-photon emitters and single spin sources (single defects with spin) in SiC, Si, and hBN have been demonstrated. Researchers face many materials science challenges in fabricating point defect quantum states with favorable intrinsic properties that can be perturbed by other defects either in bulk or at the surface of the devices. First principles theoretical simulations have been demonstrated as an essential tool in understanding the underlying physics of these atomic scale systems as well as in identification of potential new quantum bits and single photon emitters in wide band gap semiconductors. Therefore, tight collaboration of experimental research and atomistic simulations is essential for a rapid progress in the field. Continue reading Conference on Defects in Solids for Quantum Technologies (DSQT2022)

SCIENTIFIC REPORT ON THE “21ST INTERNATIONAL WORKSHOP ON COMPUTATIONAL PHYSICS AND MATERIALS SCIENCE: TOTAL ENERGY AND FORCE METHODS”

21th Total Energy Workshop, ICTP, Trieste (Italy), 11-13 January 2023

The “Total Energy” Workshop is held traditionally in Trieste every two years, since 1987. It is devoted to recent advances in computational condensed matter physics and materials science, based on realistic calculations of the electronic structure of complex systems. It has become one of the most popular regular events of the international ab-initio electronic-structure community. The 2023 edition confirmed this tradition, with a large number of participants, lively discussions and, furthermore, with a large number of contributed posters. Overview, speakers list, program with the relevant material (Conference Book, abstracts, list of attendees,…) are available on the web page:

https://indico.ictp.it/event/10056/ Continue reading

Psi-K/CECAM Flagship workshop “Light-matter interaction and ultrafast nonequilibrium dynamics in plasmonic materials”

CECAM/Psi-K Flagship Workshop “Light-matter interaction and ultrafast nonequilibrium dynamics in plasmonic materials”

July 18, 2022 – July 21, 2022, University of Warwick, UK

group foto of CECAM Plasmonics workshop at U Warwick

Description of Event

The Psi-K & CECAM sponsored meeting “Light-matter interaction and ultrafast nonequilibrium dynamics in plasmonic materials” was held from 18th to 21st of July 2022 at the University of Warwick. It featured 28 talks, 4 discussion sessions, and 10 posters. It was attended by 42 in-person attendees from 12 different countries and broadcast as a webinar with between 3 and 17 virtual attendees at any time.

A full theoretical description of light-matter interaction and plasmon-induced ultrafast non-equilibrium dynamics is a formidable challenge that demands an intrinsically multidisciplinary and multiscale approach. A variety of different approaches based on time-dependent Density Functional Theory, many-body perturbation theory, molecular dynamics, Mie theory, continuum electrodynamics, and combinations thereof have emerged in recent years to address many of the open questions in plasmonics. Further improvements in theoretical descriptions are crucial to optimize SPP generation and amplification in materials, to tailor losses and plasmonic lifetimes, as well as to integrate plasmonic effects into semiconductor technology to create new quantum materials.  Due to the diverse aspects of this problem, a coherent research community around theoretical plasmonics is only slowly emerging.

The aim of this workshop was to assess the state of computational methods in this field, to identify major challenges, as well as to provide engagement between disparate communities to create space for cross-community collaboration. Continue reading Psi-K/CECAM Flagship workshop “Light-matter interaction and ultrafast nonequilibrium dynamics in plasmonic materials”

10th ABINIT International Developer Workshop – Part 2

10th ABINIT International Developer Workshop – Part 2
May 16-19, 2022 Guidel-Plages, France

Event website
The complete list of participants can be found here.

General presentation

The ABINIT developer workshops form a series of events, crucial for the community of ABINIT developers, organized every two years. A unique occasion for most developers to acquire or maintain a global view of the project and stay up to date with the latest capabilities, planned developments, and overall strategy. The developer workshop is always an opportunity to invite external researchers, from other codes and communities, to exchange best practices and expertise…

This workshop was the second part of the 10th ABINIT developer workshop. It was held from 16th to 19th May 2022 in Guidel-Plages (Brittany, France).

Because of the COVID19 pandemic situation, in June 2021, the meeting occurred in a fully remote version, with only remote presentations and some group discussions. We missed several important parts of the workshop : small group discussions, thematic discussions, informal discussions, hackathons, etc. Many of the participants emphasized the need to meet again in person when the health situation permits it.

In May 2022 we organized the second part of the workshop, with a smaller number of participants, mostly based on the missing ingredients above, plus a few invited presentations. It was a complementary and entirely live/offline event, consisting of discussions, round tables and hackathons. The physical presence of developers was a requirement to have efficient round tables and informal discussions.

The workshop was mainly dedicated to implementations and decision making by the developers:

Every morning we had a session of hackathons. Divided into small groups, we worked on the ABINIT package : coding, improving the documentation, creating tutorials, interfacing the code with other software, etc. Each developer chose projects and hackathons according to his/her specific expertise in the project.

During two afternoons, we met collectively to discuss and consider the future of the code: future scientific themes, dissemination and the visibility, user experience improvement.

A third afternoon was dedicated to invited speakers’ presentations. The speakers were chosen because of their involvement in projects external/complementary to ABINIT. Continue reading 10th ABINIT International Developer Workshop – Part 2

CECAM / Psi-k workshop “Error control in first-principles modelling”

From 20th until 24th June 2022 we organised a workshop on the theme of “Error control in first-principles modelling” at the CECAM Headquarters in Lausanne (workshop website). For one week the workshop unified like-minded researchers from a range of communities, including quantum chemistry, materials sciences, scientific computing and mathematics to jointly discuss the determination of errors in atomistic modelling. The main goal was to obtain a cross-community overview of ongoing work and to establish new links between the disciplines.

Amongst others we discussed topics such as: the determination of errors in observables, which are the result of long molecular dynamics simulations, the reliability and efficiency of numerical procedures and how to go beyond benchmarking or convergence studies via a rigorous mathematical understanding of errors. We further explored interactions with the field of uncertainty quantification to link numerical and modeling errors in electronic structure calculations or to understand error propagation in interatomic potentials via statistical inference.

Continue reading CECAM / Psi-k workshop “Error control in first-principles modelling”

Report for the workshop “Astrochemistry meets Surface Science: Theoretical Frontiers”

Scientific Report for the workshop “Astrochemistry meets Surface Science: Theoretical Frontiers”

April 5th – 8th 2022

Aarhus Institute of Advanced Studies, Aarhus University, Denmark

Objectives:

The goal of the workshop was to bring closer together the research communities of theoretical Astrochemistry and theoretical (under Earth conditions) Surface Science. These two fields often address very similar questions, while using the exact same techniques and methodologies (e.g. electronic structure methods such as density functional theory, molecular dynamics or kinetic Monte Carlo simulations). And yet, despite these similarities, a noticeable communication gap exists between the two communities. Our multidisciplinary workshop aimed to bridge this gap and help establish new networking and collaboration ties between these fields.

The workshop covered a broad range of topics ranging from surface reaction networks and kinetic models to the characterization of interstellar ices and questions of energy dissipation and heat transport. In parallel to the underlying scientific questions, special focus was placed on theoretical and methodological aspects, as well as computational and numerical tools that are used in either one or both of the fields of astrochemistry and Earth-related surface science.

Continue reading Report for the workshop “Astrochemistry meets Surface Science: Theoretical Frontiers”

Scientific Report on the Wannier 2022 Workshop

ICTP, Trieste (Italy), 16-27 May 2022

The last two decades have witnessed a tremendous growth in the use of Wannier functions (WFs) for first-principles electronic structure calculations. Beyond providing fundamental insights on several aspects of the electronic structure, from chemical bonding to electrical polarisation, topological invariants, Berry curvature and more, WFs have found applications in a plethora of different domains. 

The software package WANNIER90 has become a reference for calculating maximally-localised Wannier functions (MLWFs) [1,2] and related properties [2,3,4]. As Wannier functions are independent from the basis sets used to represent the electronic structure in the underlying first-principles calculations, WANNIER90 can be interfaced to virtually any electronic-structure code. Indeed, most of the major electronic-structure packages have already an interface to WANNIER90, including Quantum ESPRESSO, ABINIT, VASP, Siesta, Wien2k, Fleur and Octopus. 

The availability of a robust MLWF code that is connected to several ab-initio engines has acted as a fertiliser for the birth of independent computational efforts aimed at calculating complex materials properties by leveraging WFs. Several independent packages exploiting MLWFs and WANNIER90 exist nowadays, targeting a number of properties, from electron-phonon coupling [5] (EPW) to topological invariants [6] (Z2Pack), surface spectral densities [7] (WannierTools), Berry-phase related properties [8] (Wannier Berri), tight-binding models (PythTB, TBModels), high-throughput calculations [9] (AiiDA-Wannier90), dynamical mean field theory (TRIQS), just to mention a few.

Wannier 2022 has been an event that put together the community behind these symbiotic packages that form a research and software ecosystem built upon the concept of MLWFs. The workshop has served the two-fold objective of teaching several techniques enabled by Wannier functions to young researchers and fostering an integration between all the packages composing the Wannier ecosystem, contrasting fragmentation and duplication of efforts.

This workshop has been generously funded by ICTP, Psi-k, MaX, NCCR MARVEL and CECAM. The computational infrastructure to run the hands-on tutorials has been provided by ICTP through their ICTP Cloud.   

The workshop was run by 6 directors:

  • Antimo Marrazzo, University of Trieste
  • Roxana Margine, Binghamton University
  • Sinisa Coh, University of California Riverside
  • Stepan Tsirkin, University of Zurich
  • Giovanni Pizzi, EPFL
  • Nicola Seriani, ICTP (local organiser)

The event comprised two parts, a summer school (first week) and a developers meeting (second week). 

Continue reading Scientific Report on the Wannier 2022 Workshop

Report on the Theoretical Spectroscopy Lectures

Scientific Report for the
Theoretical Spectroscopy Lectures
March 21-25, 2022
CECAM-HQ-EPFL, Lausanne, Switzerland

Objectives:
The aim of the school was to give a deep introduction to the theoretical and practical aspects of the electronic excitations which are probed by experimental techniques such as optical absorption, EELS, and photoemission (direct or inverse). From the theory point of view, excitations and excited state properties are out of the reach of density-functional theory (DFT), which is a ground-state theory. In the last thirty years, other ab-initio theories and frameworks, which are able to describe electronic excitations and spectroscopy, have become more and more used: time-dependent density-functional theory (TDDFT) and many-body perturbation theory (MBPT) or Green’s function theory (GW approximation and Bethe-Salpeter equation BSE). In fact, computational solutions and codes have been developed in order to implement these theories and to provide tools to calculate excited state properties. The present school focused on these points, covering theoretical, practical, and also numerical aspects of TDDFT and MBPT, non-linear response, and real-time spectroscopies. For the first time, this year we also covered theoretical aspects of magnetic excitations. Finally, a large part of the school was devoted to the codes implementing such theories (ABINIT, 2Light, DP, EXC). Continue reading Report on the Theoretical Spectroscopy Lectures