Molecular-kinetic model of a droplet reactor in the low-temperature synthesis of nanomaterials
Voronezh State University
Open dissipative systems have recently attracted the attention of many researchers in various fields. Such systems are increasingly regarded not as exotic phenomena, but as a tool that allows solving complex problems not only in studying the fundamental types of interaction of various nature, but also in technological applications . Open systems are interesting in that, unlike closed systems, with a certain interaction with the environment, they can exhibit deviations from the equilibrium state both on a microscopic and macroscopic scale.
One example of an open system is a drop of evaporating liquid . Drop methods are widely used in problems of medical diagnostics, separation of dissolved components, synthesis of nanomaterials and other fields .
To simulate the dynamics of a drying drop, an ensemble of 1000 water molecules connected by the Lennard-Jones potential was used. A graphene layer acts as a substrate, which plays the role of boundary conditions.
To model the interaction of the molecular system with the environment, a Nose-Hoover thermostat was used. The thermostat assumes the possibility of energy dissipation, thus ensuring the openness of the system. Therefore, the total energy inside the open molecular system is not conserved. The thermostat maintains the temperature value at a certain level, and by the nature of the change in potential energy, one can judge the presence of changes in the system (phase transitions, change in entropy, etc.).
As a result, in this work, we developed a molecular kinetic model of hydrodynamic instability in an evaporating drop, adapted to the conditions of an open system.
As a result of a numerical experiment, reactive centers in a droplet reactor were established, characterized by a local redistribution of kinetic and potential energy, contributing to a local approximation of molecules in low-temperature synthesis conditions.