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A molecular dynamics simulation of water molecules through a Au nanotube with a diameter of 20 Å at bulk densities 0.8, 1, and 1.2 g/cm3 has been carried out. The water molecules inside a nanoscale tube, unlike those inside a bulk tube, have a confined effect. The interaction energy of the Au nanotube wall has a direct influence on the distribution of water molecules inside the Au tube in that the adsorption of the water molecules creates shell-like formations of water. Moreover, the high number of adsorbed molecules has already achieved saturation at the wall of the Au nanotube at three bulk densities. This work compares the distribution percentage profiles of hydrogen bonds for different regions inside the tube. The structural characteristics of water molecules inside the tube have also been studied. The results reveal that the numbers of hydrogen bonds per water molecule influence the orientational order parameter q. In addition, the phenomenon of a group of molecules bonded inside the tube can be observed as the number of hydrogen bonds increase. [ABSTRACT FROM AUTHOR]

Tricarboxylic acid derivative with three-fold symmetry in physisorbed monolayers is an important organic molecule for applications in nanotechnology. In this paper, the behaviour of a single tricarboxylic acid derivative, 1,3,5-tris(carboxymethoxy)benzene (TCMB, C6H3(OCH2COOH)3) on an Au (111) substrate at 50 K is investigated by molecular dynamics simulation. Four possible conformations of the TCMB molecule adsorbed on the Au (111) substrate are found, the difference of which is the orientation of the CH2 chain. They also display different trajectories of movement and dynamical behaviours. As the molecule migrates across the Au (111) surface, the translational motion of TCMB is always accompanied by rotational motion. The lock-and-key (LAK) geometry between the TCMB molecule of different conformations and atomic arrangement of the Au (111) surface was also observed in this study, and the result has been verified by an ab initio calculation. [ABSTRACT FROM AUTHOR]