Barostat in Molecular Dynamics Simulation
Barostats are essential tools in molecular dynamics (MD) simulations for maintaining constant pressure conditions. These tools allow for the simulation of systems under various pressure conditions, which is crucial for studying the behavior of nanostructures in different initial conditions. In LAMMPS package various barostats can be used as shown in below figure. In this post, we will discuss the two most commonly used barostats in MD simulations: the Berendsen and Nose-Hoover barostats. The Berendsen barostat is a simple approach for controlling pressure in MD approach. It works by scaling the velocities of the atoms in the system based on the difference between the initial and final pressures. This approach is effective for equilibrating systems quickly, but it does not provide accurate long-term pressure control. The Berendsen barostat is often used in the initial stages of simulations to equilibrate the system before switching to a more accurate barostat.
The Nose-Hoover barostat is a more sophisticated method for pressure control in MD simulations. It uses a set of equations to control the system’s pressure by adjusting the volume of the simulation box. The Nose-Hoover barostat is more accurate than the Berendsen barostat and provides better long-term pressure control. However, it is also more computationally expensive and may require longer simulation times. This barostat works by introducing an additional degree of freedom to the simulation, which is a variable that controls the size of the simulation box. This variable is coupled to a thermostat that controls the temperature of the system. Computationally, Nose-Hoover barostat is based on a set of differential equations that govern the evolution of this variable over time. By adjusting the value of this variable, the Nose-Hoover barostat can control the pressure of the system.
In summary, both the Berendsen and Nose-Hoover barostats are essential tools for controlling pressure in MD method. The Berendsen barostat is simple and effective for equilibrating systems quickly, but it does not provide accurate long-term pressure control. The Nose-Hoover barostat is more accurate and provides better long-term pressure control, but it is also more computationally expensive. The choice of which barostat to use depends on the specific needs of the simulation and the available computational resources.