New conference communications from the group

In June 6th 2022, our PhD student Krystof Hlinomaz presented an oral contribution entitled “Towards description of mechanical damage of thin molybdenum film upon pulsed laser irradiation” at the HPLS&A conference held in Prague.

On July 8th 2022, our new student Ghassan Aber will present a poster on DFT modeling of Ag and TiO2, realized under his previous affiliation, at the School of Laser In Materials Sciences (SLIMS) in Venice.

On July 20th 2022, T. J.-Y. Derrien will present an invited talk (30+10 min.) on transient plasmonics at the CECAM workshop “Light-matter interaction and ultrafast nonequilibrium dynamics in plasmonic materials”.

In October 2022, Krystof Hlinomaz will give an oral/poster contribution, and T. J.-Y. Derrien will give oral presentation at the “Multiscale Material Modeling” MMM conference in Baltimore.

Update on computational facilities [updated July 26th]

The group works at the moment using several sources of high power computations:

  • PRACE/DECI: the supercomputer Navigator (12 cores x 164 nodes) has now been fixed and is back online since July 20th, after 3 months of maintenance. This will be available until December 2022.
  • ELI cluster: collaboration with ELI beam-lines supercomputer Eclipse has started, while size of supercomputer is modest (16 cores x 84 nodes) but sufficient for TDDFT.
  • IT4I.cz: A new OPEN project for the Karolina supercomputer (64 cores x 720 nodes) can now be prepared (early August) and will use AMD processors. The tests on AMD have been well conclusive in our recent attempts.
  • BIATRI-SRV: the cluster of the department runs 64 cores and is sufficient for training students on Python, TTM, DFT, PBS, preparing post-processing of data and storing large amounts of simulation results.

Searching for next funding, PRACE DECI ends soon, new student arrived [updated]

The end of current funding is approaching and the group of Ultrafast Photonics is looking for its next funds. Several projects are being drafted with collaborators at the moment.

Regarding high power computation:

  • PRACE DECI Navigator in Portugal suffers from 2nd critical incident in 6 months, leading to present shutdown of the production. Edit: it may come back during week #26.
  • Note that PRACE DECI subprogram will not be renewed, although it was an excellent and modular program that provided nice timeline along with nice resources to research groups like ours.
  • Mitigation procedures are being put in place to maintain obligations regarding collaborations. Edit: ELI beamlines kindly opened their computer to me since June 20th.

Our new PhD student Ghassan ABER arrived from Morocco and is starting to work on DFT/TDDFT.

Submitted a proposal to the Grant Agency of Czech Republic (GACR)

A period of proposal drafting has started in the department, and the group of Ultrafast Photonics counts on applying to several funding sources this year to secure financial independence for next years.

On April 1st, a proposal to study the transient excitation of electrons in particular kinds of solids was submitted to the national grant agency. The results are usually known in December of the year of submission. Only 2.5 positions would be potentially funded by this proposal, for people who have already been selected. To secure our positions on a longer time, I am presently participating in drafting of other proposals, which larger amount of funds for salaries.

Incoming oral presentations at international conferences

Although the funding context is quite intense, several presentations in international conferences will be provided this year.
1. March 14th-16th, 2022: T. Derrien, invited oral presentation in FemtoMat, Mauterndorf, Austria. Main topic this year will be dealing with band structure modification during laser irradiation.
2. March 14th-18th, 2022: collaborator assoc. prof. M. Kozak will present results of joint collaboration on high harmonic generation at DPG meeting (Erlangen).
3. April, 6th-7th 2022: T. Derrien, oral presentation at SPIE Photonics EU, Strasbourg, France.
4. May 30th – June 3rd, 2022: Prof. N. M. Bulgakova will present a work on energy absorption and redistribution channels in silicon, that includes some TDDFT results from our group. EMRS Spring Meeting 2022.
5. September 11th-16th, 2022 [CANCELED]: T. Derrien, invited oral presentation at ALT22, Arcachon, France. The topic of Arcachon conference remains to be defined.

Edit: due to geopolitical context, my invited oral presentation of ALT22 is now canceled.

Invited webinar on Marie Curie Individual Fellowship and RISE programs

On Wed. 9th Feb., T. Derrien delivered an invited presentation at the webinar “Why do researchers need to be mobile?”, organized by the Mendel University (Brno, Czech Republic) in context of the EU project “ASFORCLIC”. The webinar also included a presentation of Fullbright fellowships (Czech <-> USA exchanges), COST actions and Erasmus+.

As fellow of Marie Curie individual fellowship and main contact of Atlantic project in the Czech Republic, T. Derrien presented the outcomes of the two mobility projects on career development.

New PhD student is joining the group!

A new student will be joining our group soon. MSc. Ghassan ABER is from Casablanca (Morocco), and he will be working on time-dependent density functional theory. Within the group, he will support the TDDFT activities with comparison to experimental results obtained by various collaborators, along with preparing his PhD thesis at the HiLASE Centre. He will also contribute to the ATLANTIC project. We are very much looking forward!

Electricity prices skyrocket have impacted our HPC activities in January

The price of electrical energy has been skyrocketing last year. As a result, the cheapest supplier of Czech Republic, Bohemia Energy has now bankrupted, forcing several institutions to transfer their contract to other, more expensive suppliers. Unfortunately, cost for electricity in future will be multiplied by a factor close to 4 (and a factor 10 during the time to negotiate new contracts!), hence impacting the activities in High Power Computation of Czech Republic. Note that similar problems took place in Poland and Norway last months as well.

IT4Innovation, the Czech national supercomputing facility located in Ostrava, has expressed difficulties through their website. On Tuesday, the IT4I users council has met to discuss this extraordinary situation, where mitigation actions were discussed.

Our other computational center, provided by PRACE DECI in Portugal, got an incident due to electrical interruption that has damaged their facility. Finally, the production has restarted in the end of January.

As a result, our high power computation activities have been strongly reduced in second part of January and could partially restart at the end of the month. While our PRACE-DECI project will continue to fully support our activities, it is unlikely that our access to IT4I will be operating again before the end of our project IT4I-OPEN-20th FLAMENCO on March 21st, thus decreasing our number of available core-hours on that project.

Photo-ionization dynamics in solids: our new publication appeared in Physical Review B

The international team of researchers from the HiLASE Centre, Czech Republic, and the Max Planck Institute for Structure and Dynamics of Matter, Germany, has performed a theoretical study shedding light on the electron dynamics in crystalline semiconductors irradiated by ultrashort laser pulses. Based on first-principles time-dependent density functional theory (TDDFT) implemented on high power computers, the study provides deep insights on the ultrafast laser induced metallization of semiconducting materials. In their work, the scientists performed a comparison of the widely employed Keldysh theory of photoionization and the Drude model describing free carrier optical response with the data of the TDDFT simulations for a wide range of laser irradiation parameters. Although qualitatively a reasonable agreement was obtained, first principle simulations enable quantitative predictions of the photoionization rates and of the absorbed energy within and beyond the validity ranges of the analytical theories.

This work opens new routes for understanding laser-induced phenomena important for the development of novel applications in ultrafast photonics, the field where the band structure of materials can be engineered during their illumination by ultrashort laser pulses. The employed methodology can be used for smart choice of materials to achieve desired transient optical, electronic, and magnetic properties controlled by laser irradiation.

A joint paper on this subject has been recently published in a prestigious journal Physical Review B (Impact Factor of 4.036) of the American Physical Society.