Program

P.14 -- Poster, NCTP-41

Date: Tuesday, 2 August 2016

Time: 08h30 - 10h00

Cooling rate effects on formation of 2D solid with square lattice structure from liquid state

Nguyen To Nga (1), Vo Van Hoang (2), Nguyen Hoang Giang (2)

(1) Faculty of Fundamental Science, PetroVietnam University; (2) Comp. Phys. Lab, HoChiMinh City Univ. of Technology, Vietnam National University - HoChiMinh City

Cooling rate effects on formation of 2D solid with square lattice structure from liquid state are studied by molecular dynamics (MD) simulation. The considered models consist of 6400 particles interacting via the square interatomic potential which is proposed by M. Rechtsman et al. (Phys. Rev. E 73, 011406 (2006)). Models are obtained by cooling from the melt at various cooling rates of $10^{-6}$, $10^{-5}$ and $10^{-4}$ per MD step. Evolution of total energy per atom, specific heat, radial distribution function (RDF), and mean coordination number etc. is studied. Depending on the cooling rate used in simulation, crystallization or glass formation can occur. It is found that the crystallization of the 2D liquid with a square potential exhibits a first-order-like phase transition behavior. We find that main structural defects in the obtained 2D crystals are vacancies of various sizes and shapes, double triangles splitting from a strongly distorted square, rings of various sizes differed from 4-fold and distorted squares. Moreover, structure of the obtained 2D crystals is not homogeneous and it exhibits ‘static heterogeneity’, i.e. it contains clusters of atoms with different bond-orientation orders. Atomic mechanism of solidification of the system is studied via analysis of spatio-temporal arrangements of solid-like atoms occurred during the cooling process. Solidification occurs via homogeneous nucleation of nuclei of new phase and their subsequent growth following classical nucleation theory. Acknowledgements: This research is funded by Vietnam National Foundation for Science and Technology Development (NAFOSTED) under Grant 103.01-2014.86.

Presenter: Nguyen To Nga