Category Archives: Reports

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

Report on the “ML-IP 2021” workshop (Young and Early-career Researchers’ Tutorial on Machine Learning Interatomic Potentials)

Machine learning potentials have now established themselves as a method of choice in many atomistic simulation projects. This tutorial workshop was aimed at young and early-career researchers who are interested in using machine learning potentials in their work, but are unsure of where to start or of how feasible the proposed application would be.

While the field continues to produce new theoretical and methodological advances, there is now a large class of systems that can be treated with existing, established methods. The main issues now for new researchers entering the field are, first, choosing between the many different machine learning methods (and correspondingly many software packages) available, and second, learning about simulation workflows and best practices that are often undocumented, unwritten “common knowledge”.

The workshop was designed with two main aims: First, to give these researchers a solid introduction in the basic scientific techniques of designing, fitting, and validating a machine learning potential for a new system. Second, to provide a platform for young researchers interested in using machine learning potentials in their work to connect to those involved in developing methods for machine learning potentials, in order to accelerate the adoption of machine learning techniques in the wider atomistic simulation community. Continue reading Report on the “ML-IP 2021” workshop (Young and Early-career Researchers’ Tutorial on Machine Learning Interatomic Potentials)

The 17th ETSF Young Researchers’ Meeting

Group picture in front of the “Torre dell’Elefante”, one of the entrances of “Castello”, the historical center of Cagliari where the conference was held.
ETSF YRM 2021 — September 6-10, Cagliari (Italy).

The Young Researchers’ Meeting (YRM) of the European Theoretical Spectroscopy Facility (ETSF) is an annual meeting which involves researchers in theoretical materials science at the early stages of their careers (i.e. PhD students and post-doctoral researchers).

ETSF YRM 2021 took place in Cagliari (Italy), in the frame of the wonderful and unique landscape of Sardinia. The conference has been held in the auditorium of the Faculty of Architecture, in the spectacular setting of Collegio dei Gesuiti, an historical building dating back to the 17th century. Because of the sanitary crisis due to Covid-19 pandemic, and because of the consequent necessity to maintain security distances, the number of participants was restricted. However, in order to give to all the applicants the possibility to attend the meeting, all the talks were broadcast via Zoom.

The YRM of ETSF aims to give to young researchers the opportunity to present their work and to share their knowledge in state-of-the-art theoretical methods for solid state physics, in an informal context which stimulates networking and exchange between peers. It also promotes meeting between young researchers and private companies interested in profiles with a strong scientific backgrounds. To this purpose, one of the session of the conference hosted some former researchers now working out of academia, which shared with the participants their experiences. Continue reading The 17th ETSF Young Researchers’ Meeting

Report on the Q-MS School 2021

Q-MS School 2021 Group Photo at the Lone Star Marina and Lodge, Pilot Point, Texas.

From the 11th to the 13th of October 2021 the first school on multiscale models in Quantum Espresso was held in Texas, at the Lone Star Lodge and Marina, near Pilot Point. The school welcomed 22 in person participants, with 7 instructors from 3 US institutions. More than half of the in-person participants belong to groups that are under-represented in computational physics. While the initial plan for the school was to be in person-only, due to the pandemic situation in Texas and the rules that hindered international travelers to enter the US, the school was converted into a hybrid event. More than 450 participants registered to join the school remotely, with more than 100 participants joining specific Zoom lectures. Details on the country of origin and seniority of the registered participants are summarized in the figure below.

Q-MS School 2021 attendance (virtual and in person)

All the lectures were recorded and posted on the school website, accessible at any time for registered and non-registered participants. The school was sponsored by Psi-k and the National Science Foundation (CSSI and CHE programs) under awards #1931479 and #1945139. Continue reading Report on the Q-MS School 2021

Report on the Virtual Psi-k GreenALM Hands-on Tutorial 2021

GreenALM LogoGreenALM_2021_Logos_InstitutionsThe virtual Psi-k GreenALM Hands-on Tutorial 2021 took place from Oct. 11-14, 2021 in virtual form (https://greenalmtutorial.mcl.at/). It was organized by the Materials Center Leoben Forschung GmbH (www.mcl.at) together with the team from the Vienna Scientific Cluster and Co-organizers from KTH Stockholm and Montanuniversität Leoben and was additionally funded by Psi-k and EuroCC Austria. Continue reading Report on the Virtual Psi-k GreenALM Hands-on Tutorial 2021