ELFT HÍRADÓ

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SZFI SeminarPusztai LászlóWigner RCP SZFIUnderstanding the structure of 
liquids: a 35-year long experiment Tuesday, 29 November 2022, 10:00, KFKI 
Campus, Bldg. 1, 2nd floor, Conference RoomTraditionally, the determination 
of the structure of a liquid consisted of the following steps: (1) 
neutron/X-ray diffraction measurement, (2) corrections, to yield the 
structure factor (information in the reciprocal space), (3) 
Fourier-transformation, to yield the radial distribution function, RDF 
(information in real space), (4) interpretation of the RDF (for obtaining, 
e.g., the coordination number, i.e., the number of neighbouring particles in 
the first coordination shell). Possibilities for multicomponent liquids (e.g. 
simple molten salts, or pure water) have been very limited: the technique of 
neutron diffraction with isotopic substitution had to be applied. In the 
introductory part of the seminar, I will briefly outline this traditional 
route, along with some basic elements of the characterization of the liquid 
structure.The situation has changed quite a lot with the appearance of the 
Reverse Monte Carlo (RMC) method of structural modeling [1]. In short, RMC 
makes use of a simulation box (containing thousands of particles) and moves 
atoms around until measurable structural information (most frequently, the 
structure factor) that is calculated for the simulation box becomes 
consistent with experimental data (within errors). A major advantage of the 
method is that no interatomic potential functions are necessary. In the 
second section of the presentation, the RMC algorithm will be introduced, 
with quite a few technical details. Difficulties, shortcomings and 
misunderstandings will also be discussed.In the final part of the talk, I 
will provide an overview of what we have learnt about the structure of 
liquids by means of combining diffraction experiments and Reverse Monte Carlo 
modeling. Examples from the simplest of liquids, like liquid argon, to rather 
complicated ones, like liquid water and alcohols, will be touched upon. I 
will elaborate on the structure of one group of molecular liquids, those 
containing molecules of tetrahedral shape (e.g., carbon tetrachloride), where 
(as I believe, at least) a full picture could be provided [2].[1] R. L. 
McGreevy, L. Pusztai, Molec. Simul. 1, 369 (1988)[2] Sz. Pothoczki, L. 
Temleitner, L. Pusztai, Chem. Rev. 115, 24, 13308 (2015)Join Zoom 
Meetinghttps://wigner-hu.zoom.us/j/82741420040?pwd=eU4wdVVPQ0ZCRjVjd0dCR2dsTW4rUT09Meeting
 ID: 827 4142 0040Passcode: 672961 Minden érdeklődőt szívesen látunk! - 
Everyone is welcome to attend.Attila Nagysem-admin AT szfki.hu