where N is the number of atoms, Ω is the volume of a cubic simulation box and s i is a fraction between 0 and 1. As a result, the Lagrangian, i.e., a function that describes the dynamic behavior of a system, is expressed in terms of new scaled coordinates, depicting a fluid in a container with variable volume. Here, the fluid can be compressed or decompressed by a piston with a fictitious mass M . It is important to note that the decay of volume fluctuation is influenced by the mass of the piston.