CMSP

Europe/Rome 2021-12-07 11:00:00 2021-12-07 12:00:00 CMSP Seminar (Joint ICTP/SISSA Statistical Physics): Web models as generalizations of statistical loop models Augustin Lafay (ENS, Paris) Two dimensional gases of non intersecting loops have been a subject of study in mathematical physics for more than thirty years because of their numerous connections to integrability, two dimensional conformal field theory, random geometry and combinatorics. In this talk, I will present a natural generalization of loop models to gases of graphs possessing branchings. These graphs are called webs and first appeared in the mathematical community as diagrammatic presentations of categories of representations of quantum groups. The web models posses properties similar to the loop models. For instance, it will be shown that they describe, for some tuning of the parameters, interfaces of spin clusters in Zn spin models. Focusing on the numerically more accessible case of Uq(sl3) webs (or Kuperberg webs), it is possible to identify critical phases that are analogous to the dense and dilute phases of the loop models. These phases are then described by a Coulomb Gas with a two component bosonic field. Hybrid seminar: Virtual and SISSA room 134 ICTP pio@ictp.it 7 Dec 2021

Europe/Rome 2021-12-15 11:00:00 2021-12-15 12:00:00 CMSP Seminar (Atomistic Simulation Webinar Series): Density-functional theory with extended Hubbard functionals: recent developments and applications Density-functional theory (DFT) with extended Hubbard functionals is a powerful method for studying complex materials containing transition-metal and rare-earth elements, owing to its accuracy in correcting self-interactions and its low computational costs [1]. There are two key elements in these formulations which are closely interconnected: i) the choice of the on-site U and inter-site V Hubbard parameters, and ii) the choice of the Hubbard manifold. Recently, we developed an automated and reliable approach for the first-principles determination of U and V using density-functional perturbation theory (DFPT) [2,3]. In this talk I will show that DFPT allows us to reduce significantly computational costs, improve numerical accuracy, and fully automate the calculation of the Hubbard parameters by recasting the linear response of a localized perturbation in supercells into an array of monochromatic perturbations that can be calculated in the primitive cell. This framework can be used with different Hubbard manifolds, such as nonorthogonalized and orthogonalized atomic orbitals, including the respective calculation of Pulay (Hubbard) forces and stresses [4] that are needed for the self-consistent evaluation of Hubbard parameters [3]. I will show how this formalism can be used for the evaluation of such properties as voltages in Li-ion batteries, formation energies of oxygen vacancies in perovskites, and I will discuss the applicability of this formalism for improving band gaps with respect to standard DFT [5] and its use for searching of novel materials for the photocatalytic water splitting [6].  Finally, I will present the extension of this framework to the calculations of phonons [7] and electron-phonon coupling [8] in selected transition-metal compounds. These tools are implemented in the open-source Quantum ESPRESSO distribution [9] and are available to the community at large. [1] V.L. Campo Jr and M. Cococcioni, J. Phys.: Condens. Matter. 22, 055602 (2010). [2] I. Timrov, N. Marzari, M. Cococcioni, Phys. Rev. B 98, 085127 (2018). [3] I. Timrov, N. Marzari, M. Cococcioni, Phys. Rev. B 103, 045141 (2021). [4] I. Timrov, F. Aquilante, L. Binci, M. Cococcioni, N. Marzari, Phys. Rev. B 102, 235159 (2020). [5] N.E. Kirchner-Hall, W. Zhao, Y. Xiong, I. Timrov, I. Dabo, Appl, Sci. 11, 2395 (2021). [6] Y. Xiong et al., Energy Environ. Sci. 14, 2335 (2021). [7] A. Floris, I. Timrov, B. Himmetoglu, N. Marzari, S. de Gironcoli, M. Cococcioni, Phys. Rev. B 101, 064305 (2020). [8] J.-J. Zhou, J. Park, I. Timrov, A. Floris, M. Cococcioni, N. Marzari, M. Bernardi, Phys. Rev. Lett. 127, 126404 (2021). [9] P. Giannozzi et al., J. Phys.: Condens. Matter 29, 465901 (2017). Registration details will be announced closer to the seminar date. Virtual ICTP pio@ictp.it 15 Dec 2021

Europe/Rome 2021-12-06 12:50:00 2021-12-17 21:00:00 School on Synchrotron Light Sources and their Applications | (smr 3611) An ICTP Virtual Meeting The School will introduce young scientists to the design, operation, and research opportunities offered at a modern synchrotron light source and how such sources are realized.   The school will be held over two weeks and will consist of three modules: (1) the physical aspects concerning the design and function of the main components: accelerators, insertion devices and beamline optics (2) an overview of the arguments that can be made in order to fund and build a synchrotron light source, including socioeconomic benefit, stakeholder engagement, communication (3) Overview of common synchrotron light techniques  including synchrotron infrared techniques and XANES/EXAFS.   Topics: Fundamentals of synchrotron radiation from storage rings Fundamentals of X-ray interactions with matter Design and operation of storage rings Beamline design: Photon transport and optics Bending magnets and insertion devices Project management at a large facility Ancillary devices for light sources Socioeconomic justification Cultural heritage Stakeholder engagement/communications Starting up user operations at a new facility Industrial Applications IR microscopy Basics of X-ray crystallography and powder diffraction Basics of structural biology Fundamentals of X-ray absorption: EXAFS and XANES XRF, TXRF, GXRF and their applications in materials and life sciences Tomography Speakers: M. ALTISSIMO, Elettra Sincrotrone Trieste, Italy R. BARTOLINI, DESY, Germany K. CHAPELLE, American Museum of Natural History, USA T. D'ALMEIDA, X-TechLab, Benin S. DI MITRI, Elettra Sincrotrone Trieste, Italy A. FROIDEVAL, Helmholtz Zentrum Dresden-Rossendorf, Germany J. GILLIES, CERN, Switzerland M. HARFOUCHE, SESAME, Jordan G. IORI, SESAME, Jordan K. JAKATA, ESRF, France G. KAMEL, SESAME, Jordan L.U. KHAN, SESAME, Jordan K. KIEFER, Helmholtz Zentrum Berlin, Germany A. LAUSI, SESAME, Jordan F. LEHNER, DESY, Germany K. LORENTZ, Cyprus Institute, Cyprus G. MARGARITONDO, EPFL, Switzerland A. MIGLIORI, IAEA, Austria E. MITCHELL, ESRF, France G. SANTONI, ESRF, France K. TOUKAN, SESAME, Jordan N. VALLS, ALBA Synchrotron, Spain A. VOLLMER, Helmholtz Zentrum Berlin, Germany   Registration: there is no registration fee. Online - ICTP pio@ictp.it 6 Dec 2021 - 17 Dec 2021