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Evaluation of ReaxFF potentials for the interactions between 3-fold coordinated carbon systems and molecules

Data: Giovedì 19 maggio 2022 - 11:00
Link (Google Meet): https://meet.goto.com/351214949
Speaker: Zacharias Fthenakis (NEST, Istituto Nanoscienze-CNR and Scuola Normale Superiore)

Abstract: To decide which method to use for a theoretical calculation of a specific property of a system, depends mainly on the property itself and the size of the system. The reason is that an accurate calculation is very time consuming and it will turn into an impossible task as the system size increases. In other words, the size of the system is inverse proportional to the accuracy of a calculation which can be used to study that system. Thus, the more accurate and more time consuming calculations can be performed only for small systems, while for larger systems it is unavoidable the use of less accurate methods. Due to those limitations the very accurate configuration interaction methods can be used for systems composed of some few atoms, the relatively accurate density functional theory method for systems composed of some tenths or few hundreds of atoms, the less accurate semi-empirical tight binding methods for systems of some hundreds or few thousands of atoms, while the even less accurate classical potential approximations can be used for systems composed of thousands or even millions of atoms. The unavoidable reduction of the accuracy, however, is a key factor for the quality of the results obtained from the calculations and it is therefore of high importance to know the limits of the accuracy and the performance of an approximation for several properties of a system. In the present talk those limits and the performance of the so called ReaxFF classical potentials for sp2 carbon systems are discussed. ReaxFF are considered nowadays as the state of the art classical potentials, which can be used for calculations under reactive conditions. The results of those potentials for (a) the structural, energetic, mechanical and phonon properties of graphene and its response under strain, (b) the energetic and mechanical properties of (n,0) and (n,n) carbon nanotubes and their response under strain till fracture, (c) the energetics of fullerene isomers, (d) the formation energy and the structural deformations of several graphene defects, like addatoms, Stone-Walles transformations and vacancies and (e) the energy barriers for the permeation of small molecules through graphene pores are discussed and compared with ab-initio density functional theory results, as well as, the results of other classical potentials.

This research was funded by the projects (i) EU-H2020 FETPROACT LESGO (Agreement No.952068), (ii) MONSTRE-2D PRIN2017 KFMJ8E of the Italian Ministry of University and Research, (iii) “nanoporous GrAphene membrane made without TransfEr for gas Separation – GATES” (MIS 5041612), (iv) “Advanced Materials and Devices” (MIS 5002409) and (v) “National Infrastructure in Nanotechnology, Advanced Materials and Micro - / Nanoelectronics” (MIS 5002772) of the Operational Program “Competitiveness, Entrepreneurship and Innovation” (NSRF 2014-2020), co-financed by Greece and the European Union (European Regional Development Fund).

Host: Fabio Taddei (CNR)

[Ultimo aggiornamento: 12/05/2022 10:18:22]