Molecular dynamics study of Laplace pressure in solid-state nanostructures

The paper provides a comprehensive molecular dynamics study of nanostructures compressed by a system of surface atoms to analyze their surface tension. Surface tension is here understood as phenomena resulting from the presence of surface atoms. All main properties of nanostructures are conditioned by a highly developed surface. The number of surface atoms and their energy are comparable to those of bulk atoms. It is shown that at cryogenic temperatures, spherical solid-state clusters of size up to 10 nm reveal excess pressure. This pressure owes to compression of the clusters by surface atoms. The molecular dynamics study of thermodynamic properties of the nanostructures demonstrates that the increase in pressure in clusters of size from 2 to 9 nm with temperature is due to the gas component and the slope on the temperature dependence of thermal pressure does not depend on the cluster size. It is also shown that the surface tension coefficient decreases with an increase in temperature. A theoretical expression for this dependence is derived suggesting that there exists a certain Laplace temperature at which compressive pressure in a cluster is balanced by thermal gas pressure.