Mechanism of 1,12-Dicarba-closo-dodecaborane Mobility on Gold Substrate as a Nanocar Wheel
SMH Lavasani and HN Pishkenari and A Meghdari, JOURNAL OF PHYSICAL CHEMISTRY C, 120, 14048-14058 (2016).
We studied the mobility of p-carborane on a gold surface by analyzing the potential energy surfaces (PES) and simulating the motion of p-carborane using the classical molecular dynamics (MD) method. In the first section, we calculated the PES of p-carborane molecules on a gold surface during pure translation (sliding) and pure rotation independently and then employed this PES to predict the probable motion of p-carborane. These calculations were performed in several major orientations during sliding as well as different fixed positions during rotational movements to enable us to find the p-carborane motion threshold on a gold surface. In the second section, we use classical MD in isothermal conditions to specify the regime of motion of p-carborane at different temperatures. We found that by raising the temperature, three different regimes of motion may be observed: jumps to adjacent cells, long jumps, and continuous motion. To better understand the change of motion regime of p-carborane on the gold surface, we proposed a quantified parameter for describing the motion. Both MD and PES results demonstrated that rotation around a horizontal axis is more difficult than pure sliding, while rotation around a vertical axis is easier and likely to occur even at low temperatures. The results of this study not only provide quantitative criteria for specifying the regime of motion of p-carborane on a gold surface but also can be used to estimate the behavior of thermally driven or motorized p-carborane-based nanocars and their motion on similar substrates.
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