Theoretical study of the effects of intermolecular interactions in self‐assembled long‐chain alkanes adsorbed on graphite surface

In this paper, we studied the physisorption of long‐chain alkanes C n H 2 n +2 ( n = 8, 16, 24, 34) on a graphite surface using molecular mechanics simulations. The computed results illustrated that the interactions between adsorbed molecules and substrate are dominated by van der Waals forces whereas the electrostatic interactions are very small. It was found that the ratio of the alkane molecule–molecule interactions (two‐dimensional crystallization energy) to the interactions between alkane and graphite (adsorption energy) ranges from ∼2 : 5 to 3 : 5. The adsorption stability and immobility of the alkanes increases proportionally with an increase in the chain length. It was concluded that the lateral interactions between adsorbed molecules are important to the formation of ordered two‐dimensional lamellae. The theoretical results support the scanning tunneling microscopy (STM) observation of alkylated aromatic compounds on a graphite surface.