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[Fizinfo] Szemináriumok - Seminars: Prof. Andrea Di Cicco

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  • From: Szeminárium koordinátor <sem-admin AT>
  • To: SZFI Szeminárium <seminar AT>,Fizinfo <fizinfo AT>
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  • Subject: [Fizinfo] Szemináriumok - Seminars: Prof. Andrea Di Cicco
  • Date: Sat, 26 Nov 2022 06:00:01 +0100 (CET)
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SZFI SeminarProf. Andrea Di CiccoPhysics Division, University of Camerino
(Italy) (host: Pusztai László)Advances in modelling X-ray absorption
spectroscopy by reverse Monte CarloThursday, 1 December 2022, 10:00, KFKI
Campus, Bldg. 1, 2nd floor, Conference RoomModern extended X-ray absorption
fine structure (EXAFS) analysis is based on multiple-scattering calculations.
Those calculations are carried out for fixed atomic configurations and proper
account of the thermal and static disorder, corresponding to well-defined
pair and higher-order distribution functions, can be obtained using different
methods. The application of the Reverse Monte Carlo (RMC) method[1] is able
to provide tridimensional models of the atomic structure compatible with a
given set of experimental data, producing useful and consistent structural
models. This method has been proposed and applied also to EXAFS data by
several authors in the last 25 years and has been fully implemented in the
framework of the RMC-GnXAS method for EXAFS data-analysis [2-7] and applied
mainly to liquid and molecular systems. Here we present the extension and
application of this method to multiple-edge studies of molecules, crystalline
solids and liquids, including the long-range constraints provided by other
techniques (e.g. diffraction). The potential and possible weaknesses of the
RMC method are discussed, as well as the importance of accounting for the
effect of noise levels in XAFS data. Results of RMC refinements are reported
for several exemplary cases including Br2 and GeI4 molecular gases,
crystalline Ge and AgBr, amorphous Ge and liquid AgBr. Those applications
show the general interest for this method, and the importance of combining
multiple set of data for improving the accuracy of the structural refinement
both at short and long range. [1] R. L. McGreevy and L. Pusztai, Mol. Sim.,
1988, 1, 359–367.[2] official GnXAS website.[3] A. Di
Cicco, A. Trapananti, S. Faggioni, and A. Filipponi, "Is there icosahedral
ordering in liquid and undercooled metals?", Phys. Rev. Letters 91, 135505
(2003)[4] A. Di Cicco, and A. Trapananti, "Reverse Monte Carlo refinement of
molecular and condensed systems by x-ray absorption spectroscopy", J. Phys.
Condens. Matter 17 S135 (2005).[5] A. Di Cicco, F. Iesari, S. De Panfilis, M.
Celino, S. Giusepponi, A. Filipponi, Local fivefold symmetry in liquid and
undercooled Ni probed by x-ray absorption spectroscopy and computer
simulations, Physical Review B rapid comm. 89, 060102 (2014).[6] A. Di Cicco,
F. Iesari, A. Trapananti, P. D'Angelo, A. Filipponi, "Structure and atomic
correlations in molecular systems probed by XAS reverse Monte Carlo
refinement", J. Chem. Phys. 148, 094307 (2018).[7] A. Di Cicco and F. Iesari,
Physical Chemistry Chemical Physics, 24, 6988-7000 (2022).Join Zoom
ID: 814 1514 0766Passcode: 569885&nbsp;Minden érdeklődőt szívesen látunk! -
Everyone is welcome to attend.Attila Nagysem-admin AT

  • [Fizinfo] Szemináriumok - Seminars: Prof. Andrea Di Cicco, Szeminárium koordinátor, 11/26/2022

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