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Twist-to-writhe conversion phenomenon in nanowires: a computational study

Grant number: 20/05662-5
Support type:Scholarships in Brazil - Scientific Initiation
Effective date (Start): August 01, 2020
Effective date (End): July 31, 2021
Field of knowledge:Physical Sciences and Mathematics - Physics - Condensed Matter Physics
Principal Investigator:Alexandre Fontes da Fonseca
Grantee:Julia Aznar
Home Institution: Instituto de Física Gleb Wataghin (IFGW). Universidade Estadual de Campinas (UNICAMP). Campinas , SP, Brazil

Abstract

Filaments of different sizes have a similar and universal behavior when subjected to large torsional stresses. When their ends are kept fixed or connected one to each other forming a closed filament, these structures can undergo a phenomenon of topological transformation known as twist to-writhe conversion (TWC). This transformation consists of the formation of contortions or helical turns in initially straight but very twisted threads due to relaxation of the large torsional stress. This phenomenon happens in many everyday situations such as in telephone cords and garden hoses, and in less known situations such as suboceanic cables and DNA molecules. Although well known to researchers in the field of rod mechanics and elasticity, only few studies exist in the literature regarding the TWC phenomenon in one-dimensional nanostructures. In this project, we propose a computational study, using classical molecular dynamics methods, of the TWC phenomenon in two types of 1D nanostructures: diamond and metallic nanowires. We will investigate how the difference between the types of chemical bonding (covalent and metallic) interferes with the process of converting from torsion to contortion. In view of the technological trend of miniaturization of electronic devices, the results of this study may be of interest in several applications, with the potential to result in scientific publications.