The Psi-k Community

MISSION: Psi-k is a Europe-based, worldwide network of researchers working on the advancement of first-principles computational materials science. Its mission is to develop fundamental theory, algorithms, and computer codes in order to understand, predict, and design materials properties and functions. Theoretical condensed matter physics, quantum chemistry, thermodynamics, and statistical mechanics form its scientific core. Applications encompass inorganic, organic and bio-materials, and cover a whole range of diverse scientific, engineering, and industrial endeavours. Key activities of Psi-k are the organization of conferences, workshops, tutorials and training schools as well as the dissemination of scientific thinking in society.

Psi-k is a bottom-up researchers’ network, established in 1994, to build strength and cooperation in the field of computational electronic structure. Psi-k activities are coordinated by a Board of Trustees, a Scientific Advisory Committee, and 16 Working Groups. These activities encompass the organization or co-sponsoring of ~30 workshops, conferences, schools or tutorials every year, an annual research conference jointly with CECAM, and a major conference covering the entire field every 5 years.

In addition, Psi-k produces a regular newsletter with extensive scientific highlights, and allows researchers to advertise job openings, events, and other topics of mutual interest through its 5000+ members mailing list.

This new website — introduced in  2015 to replace a venerable old site that provided sterling service over many years — offers a much more flexible modern design and functionality and it is to be hoped that it will provide even more stimulus for collaboration and cooperation amongst its members. Instructions regarding how to use it are here.

Psi-k is a registered charity and can only continue to operate thanks to the contributions from our member organisations and institutions. If you would like to make a donation to Psi-k please contact us.

SCIENTIFIC REPORT ON “HOW EXCITING! WORKSHOP ON EXCITATIONS IN SOLIDS HUMBOLDT-UNIVERSITÄT ZU BERLIN”, BERLIN, GERMANY, JULY 31 – AUGUST 9, 2018

The fourth Berlin edition of the “HoW exciting! Workshop on excitations in solids” took place in the Campus Adlershof of the Humboldt-Universität zu Berlin between July 31st to August 9th, 2018. Excitations in solids, which were the core topic of the workshop, are among the most exciting phenomena in condensed-matter physics. In this context, the electronic-structure approach provided by density-functional theory (DFT) is only the first level in a hierarchical set of models which are needed to quantitatively describe and understand these phenomena in real materials. The main goal of the “HoW exciting! Workshop on excitations in solids” was to address these issues and to establish a robust relationship between the most recent advances in theoretical and computational methods and the different domains of applicability with respect to experiments. Specifically, in this workshop the state-of-the-art of theoretical and computational approaches to describe different kinds of excitations (optical, magnetic, vibrational, etc.) in solid-state materials were presented. Future perspectives of these methodologies and their applications in different research fields were discussed and new connections between theoretical and experimental groups, who are investigating excitations in materials from different perspectives were established. The main topics spanned the whole range of first-principles methods for excitation processes in solids, including electronic excitations, electron-phonon coupling, core-excitations, and non-equilibrium processes.

The event was organized in two main blocks:

  • A hands-on tutorial on the exciting code conducted by the developers’ team within the solid-state theory group of the Physics Department of the Humboldt-Universität zu Berlin who also organized this event. The tutorial took place between July 31st and August 5th, 2018.

  • An international conference with 23 invited speakers, 6 contributed talks, and a poster session. The conference took place on August 6th – 9th, 2018. A complete list of the invited speakers can be found here.

Hands-on Tutorial

The tutorial was organized as follows. In the first two half-days, keynote lectures, given by internationally recognized speakers, introduced the underlying theory of DFT and many-body perturbation theory (MBPT). In the afternoon of the second day, the tutorial sessions started. Each session was organized in two blocks. First, a general overview introduced the specific parts of the code. Next, a practical session in the computer lab was guided by members of the exciting team. In this way, participants had the opportunity to put their knowledge into practice with the help of the tutorials of the code. During the last day of the tutorial, Sunday, August 5th, the participants had the opportunity to engage themselves with their own project, supported by the developers of exciting. The hands-on tutorial hosted the members of the Marie-Curie International Training Network “INFORM”. The largest majority of these early-stage researchers had an experimental background and for most of them the tutorial was the first approach ever with abinitio calculations. During the hands-on tutorial exciting nitrogen was released.

In the following, we report the list of topics of the hands-on tutorial. The detailed program can be found here.

  • Getting started
  • Kohn-Sham electronic structure
  • Exchange-correlation functionals
  • Structure optimization and elastic properties
  • Phonons
  • Self-energy and GW methods
  • Introduction to Wannier functions
  • Optical spectroscopy
  • Core excitations
  • Time-dependent DFT
  • Raman scattering
  • The NOMAD project
International Conference on Excitations in Solids

The international conference of excitations in solids was organized in 7 topical sessions:

  • Spectroscopy I: Photoemission
  • Materials I: 2D systems
  • Spectroscopy II
  • Advances in theory
  • Materials II: Hybrid materials and organic electronics
  • Materials III
  • Plasmonics and transport

Different aspects of the complex landscape of excitations in solids could be addressed and discussed, from both an experimental and a theoretical perspective. Specifically, the fundamental physical mechanisms ruling the response of materials to an external perturbation were the subject of the two Spectroscopy sessions. The presentations in the Materials sessions showed how state-of-the-art experimental and computational methods are nowadays able to address key questions in materials science. The hottest topics in the fields of photovoltaics, optoelectronics, and thermoelectrics were touched. In the session Advances in theory up-to-date developments to address challenging problems like electron-phonon coupling in solids and accurate excited states in molecules and solids were presented. The concluding session of the conference was on Plasmonics and transport.

Electronic-structure-theory methods had obviously most relevance during the workshop. The capability of DFT to characterize the ground-state properties of materials emerged in the majority of lectures and contributions. At the same time, the current limitations of this method as well as the proposed strategies to go beyond the status quo were exhaustively debated. Another main topic of discussion concerned the treatment of excited-states properties. Electronic correlations, electron-hole pairs, and out-of-equilibrium phenomena cannot be described quantitatively by semi-local DFT and for this purpose approach going beyond the mean-field description are needed. The increasing complexity coming from advanced methods such as hybrid DFT and many-body perturbation theory was extensively discussed. The connection between theory and experiment in order to jointly describe complex excited-state phenomena and to advance in parallel in terms of methodology was put in the foreground in many talks and discussions. As an outcome, it was highlighted that advances in theoretical approached need to be reflected in the novel experimental techniques, in order to give rise to new scientific breakthroughs. These exchanges, involving to a large extent also the young participants, greatly enriched the workshop and represented an added value, which will possibly be reflected in their future research work of anybody who attended it.

 

Further Information

The audience of the “HoW exciting! Workshop on excitations in solids” was large and diverse in age, career level, background and nationalities. As mentioned above, 15 participants were part of Marie-Curie International Training Network “INFORM”. The other young researchers who took part in the event were undergraduate, doctoral students, and post-doctoral scientists from different groups in Germany and abroad. Overall the number of participants was about 70, with more than 20 nations represented. While, on the one hand, this is an indication of the international relevance of the topics addressed in the workshop, on the other hand, such a diversity contributed to large extent also to the lively cultural and scientific exchange that took place during the workshop. Also in terms of gender we ensure above-average diversity. About 40% of the total number of oral presentations was given by women.

The social program complemented the scientific one, promoting further exchange among the organizers, the invited speakers, and the participants. Coffee breaks and meals organized in loco helped socialization and thereby promoted scientific discussions, which contributed essentially to the success of the workshop. To ensure the participation to at least a social event to each participant, we organized a barbecue took place on beach at the Müggelsee, the largest lake of the Berlin area, on Sunday, August 5th at the conclusion of the hands-on tutorial. The social dinner for the international conference took place on Tuesday, August 7th, in an Indian restaurant near the campus area.

The workshop received a very positive feedback from invited lecturers and attendees. Lecture slides and tutorial talks are publicly available within the exciting webpage for future dissemination. The hands-on tutorials used during the workshop referred to the release exciting nitrogen are available on the website of the code.

Physics by the Lake Workshop

The psi-k sponsored Physics by the Lake Workshop in Theoretical Condensed Matter ran in Cumberland Lodge, Windsor UK from July 30th through August 10th 2018

The course lecturers at the meeting were Sam Carr, Edward McCann, Richard Blythe, Chris Hooley, Martin Lueders, Andrew Fisher, Bartek Waclaw, Buddhapriya Chakrabarti, with technical demonstrators Raul Santos and Miriam Marques

Seminar speakers were  Graeme Ackland, Mike Payne, Julie Staunton, Raul Santos Alexandre Zagoskin and Mike Gunn

38 students attended

Lecture notes and attendance lists are available to psi-K members .https://www2.ph.ed.ac.uk/~gja/PBTL_2018_Notes.pdf Continue reading Physics by the Lake Workshop

Progresses in NonEquilibrium Green’s Functions VII

With the advent of nanoscale physics and ultrafast lasers it is now possible to directly probe real-time the correlated motion of electrons and nuclei in excited quantum states. In addition, the intensity and profile of the laser field can be tuned to control and manipulate the opto-electronic properties of a wide range of molecules and materials. All these progresses have opened new fields of research like, e.g., molecular transport, nanoelectronics, atto-physics/chemistry, nonequilibrium phase transitions, ultracold atomic gases, optimal control theory, etc.

Experiments are usually carried on large molecules, biological systems and nanostructures whose peculiar dynamical properties are inevitably linked to their atomistic structure. Thus, an ab-initio, time-dependent and quantum-mechanical approach is required for reliable calculations. The aim of this workshop was to gather together many of the most prominent theoretical and experimental scientists to advance our fundamental understanding of matter under extreme nonequilibrium conditions. Particular emphasis was given to many-body methods like Nonequilibrium Green’s Functions Theory (NEGF) and how to combine NEGF with ab initio methods like Density Functional Theory.

Read the full report.

Ab Initio Spin Modelling Workshop

CECAM-HQ-EPFL, Lausanne, Switzerland, 26-28 November 2018

Organizers: Jerome Jackson and Martin Lüders, STFC Daresbury Laboratory, UK

http://www.cecam.org/workshop-0-1549.html

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.

Read the full report here.

CAMD Summer School 2018

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.

Read the full report here.

Final report on psi-k funded Elk workshop

Organizers: J. K. Dewhurst, E. K. U. Gross, and S. Sharma

1.  SUMMARY

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.

Continue reading Final report on psi-k funded Elk workshop

Report on the Psi-k/CECAM Research Conference “Ab initio Spin-Orbitronics”

September 25, 2017 – September 29, 2017
Hotel Promenade, Montesilvano, Pescara (Italy)

Organizers:
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.

Read the full report here.

Report on CECAM Workshop: “Emerging Technologies in Scientific Data Visualisation”.

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)

Emine Kucukbenli (SISSA, Trieste, Italy)

Giordano Mancini (Scuola Normale Superiore, Pisa, Italy)

Monica Sanna (Scuola Normale Superiore, Pisa, Italy)

State of the art:

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”.

Report: Workshop on Electronic Structure Theory with Numeric Atom-Centered Basis Functions 2018, July 9-11, Munich

Participants of the workshop attending one of the seminars.

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)

Continue reading Report: Workshop on Electronic Structure Theory with Numeric Atom-Centered Basis Functions 2018, July 9-11, Munich

Ab initio (from electronic structure) calculation of complex processes in materials