We study the Soret effect in binary dimer-monomer mixtures using nonequilibrium molecular dynamics simulations and investigate the pure contribution of the internal degree of freedom of flexible molecules to the Soret effect. We observe that the thermal diffusion factor tends to decrease and change its sign as the molecules become softer. We propose two possible mechanisms for our observations: change of the molecule structures with the temperature, causing bulkier molecules to migrate to the hotter region, and asymmetry of the restitution between rigid and flexible molecules, due to which flexible molecules show larger restitution when placed at the hotter region.

中文翻译：

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软分子内部自由度对索雷特效应的贡献

我们使用非平衡分子动力学模拟研究二元二聚体-单体混合物中的Soret效应，并研究柔性分子内部自由度对Soret效应的纯贡献。我们观察到，随着分子变得更软，热扩散因子趋于降低并改变其符号。我们提出了两种可能的观察机制：随着温度的变化分子结构，使体积更大的分子迁移到较热的区域，以及刚性分子和柔性分子之间恢复原位的不对称性，因为当置于较热的地区。