The effect of slit size on stress tensor components

The pressure that applying by particles is a mechanical quantity created by random motion of particles, which has tensor properties and has 9 components that not equal toeach other, necessarily:The diagonal components of tensor included normal component Pzz and lateral components Pxx, Pyy and the non-diagonal components are shear components (Pij, i≠j, I,j=x, y, z) that are symmetrical and for this reason calculated 6 components of tensor [1]. In macroscopic system 3 diagonal components are equal and 6 non-digonal components are zero. Thermodynamic properties of a fluid confined in slit pores show deviations from those of a macroscopic fluid therefore, in slit non-diagonal components are almost zero and 3 diagonal components are not equal [2]. We performed molecular dynamics simulations of Lennard-Jones particles confined in a slit pore by using LAMMPS and investigated the effect of slits size on the value of pressure tensor components. We simulated a box with the density 0.880 and 1000 particles in temperature 1.095 and calculate the pressure tensor components. All quantities are reduced respectively to  and , that is, these LJ parameters are fixed to unity.We observed that slits with 2 4 approximately the value of the component is closer together. Shear components are negligible in all slits. The zz component has more oscillation than the main pressure compared to xx and yy, which are almost the same in larger sizes. (Shown in table 1).