Résumé
We report here the Molecular Dynamic (MD) simulations of a series of self-assembled mo-lecular monolayers adsorbed on graphite. The building bloc of the layers is a molecule of 1,3,5 - trisyrylbenzene substituted in 3,5 positions by alkoxy chains CnH2n+1O- (n= 6,8,10 and 12). Recent experimental studies [1-4] shows that at room temperature the the molecules aggregate on HOPG (highly oriented pyrolitic graphite) and form porous monolayers with the size of pore proportional to the length of alkoxy chain. The structure of the adlayer remains stable and commensurate with underlying graphite, even if orientation of molecules fluctuates within the layer. We will show that such behavior is only possible if the gauche defects in the adjacent molecular clips are formed in a cooperative way. In parallel, we investigate the stability of the film in the configurations that are - or are not - commensurate with graphite.