Electricity prices skyrocket have impacted our HPC activities in January

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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

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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.