ABSTRACT Silica and nickel are frequently used in the synthesis of carbon nanotubes by the chemical vapour deposition (CVD) process. The molecular simulation of this process requires the knowledge of force fields to model the interactions occurring between those species at the atomic scale. This work proposes a combined force field to model the silica/nickel system when these components are in contact as substrate and catalyst, respectively, in the CVD process. The proposed combined force field includes the Lennard–Jones (n–m) potential for modelling the silicon/nickel pair interactions and the Buckingham potential for the oxygen/nickel pair interactions. The combined force field is completed by the Tersoff potential to model silica (SiO2) and the Sutton–Chen potential for the cohesive forces present in the nickel clusters. Parameters for the Lennard–Jones (n–m) and Buckingham pair potentials were fitted, by the least squares technique, to interaction energies data for the silica/nickel system. The energies were obtained from Ab-initio (DFT) calculations using the VASP code. It was found that the combined force field reproduces adequately, by molecular dynamics simulation, the adherence (adsorption) of nickel clusters on the silica surface. Keeping stable this configuration is crucial in modelling the carbon nanotubes synthesis by the CVD process.

中文翻译：

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二氧化硅/镍系统的组合力场

摘要 二氧化硅和镍经常用于通过化学气相沉积 (CVD) 工艺合成碳纳米管。这个过程的分子模拟需要力场的知识来模拟原子尺度上这些物种之间发生的相互作用。这项工作提出了一个联合力场来模拟二氧化硅/镍系统，当这些组件在 CVD 过程中分别作为基材和催化剂接触时。提议的组合力场包括用于模拟硅/镍对相互作用的 Lennard-Jones (n-m) 势和用于氧/镍对相互作用的 Buckingham 势。合成力场由模拟二氧化硅 (SiO2) 的 Tersoff 势和镍簇中存在的内聚力的 Sutton-Chen 势完成。Lennard-Jones (n-m) 和 Buckingham 对电位的参数通过最小二乘法拟合到二氧化硅/镍系统的相互作用能数据。能量是使用 VASP 代码从 Ab-initio (DFT) 计算中获得的。发现联合力场通过分子动力学模拟充分再现了镍簇在二氧化硅表面上的粘附（吸附）。保持这种配置的稳定对于通过 CVD 工艺模拟碳纳米管合成至关重要。通过分子动力学模拟，镍簇在二氧化硅表面的粘附（吸附）。保持这种配置的稳定对于通过 CVD 工艺模拟碳纳米管合成至关重要。通过分子动力学模拟，镍簇在二氧化硅表面的粘附（吸附）。保持这种配置的稳定对于通过 CVD 工艺模拟碳纳米管合成至关重要。