title: Molecular dynamics simulation of amorphous SiO2 nanoparticles.
abstract: Molecular dynamics simulation of amorphous SiO2 spherical nanoparticles has been carried out in a model with different sizes, 2, 4, and 6 nm, under non-periodic boundary conditions. We use the pair interatomic potentials which have weak Coulomb interaction and Morse type short-range interaction. Models have been obtained by cooling from the melt via molecular dynamics (MD) simulation. Structural properties of amorphous nanoparticles obtained at 350 K have been studied via partial radial distribution functions (PRDFs), mean interatomic distances, coordination numbers, and bond-angle distributions, which are compared with those observed in the bulk. Calculations of the radial density profile in nanoparticles show the tendency of oxygen to concentrate at the surface as observed previously in other amorphous clusters or thin films. Size effects on structure of nanosized models are significant. The calculations show that if the size is larger than 4 nm, amorphous SiO2 nanoparticles have a distorted tetrahedral network structure with the mean coordination number ZSi-O approximately 4.0 and ZO-Si approximately 2.0 like those observed in the bulk. Surface structure, surface energy, and glass transition temperature of SiO2 nanoparticles have been obtained and presented.
authors.affiliation: Department of Physics, Institute of Technology, National University of HochiMinh City, 268 Ly Thuong Kiet, District 10, HochiMinh City, Vietnam. vvhoang2002@yahoo.com
authors.forename: Vo Van
authors.initials: VV
authors.lastname: Hoang
mesh_terms: D003198:Computer Simulation; D008956:Models, Chemical; D053758:Nanoparticles / Q000737:chemistry*; D010316:Particle Size; D044367:Phase Transition; D012822:Silicon Dioxide / Q000737:chemistry*; D013696:Temperature; D013816:Thermodynamics
chemical_list: D012822:Silicon Dioxide