Graphdiyne (GDY) has emerged as a very promising two-dimensional (2D) membrane for gas separation technologies. One of the most challenging goals is the separation of deuterium (D₂) and tritium (T₂) from a mixture with the most abundant hydrogen isotope, H₂, an achievement that would be of great value for a number of industrial and scientific applications. In this work we study the separation of hydrogen isotopes in their transport through a GDY membrane due to mass-dependent quantum effects that are enhanced by the confinement provided by its intrinsic sub-nanometric pores. A reliable improved Lennard-Jones force field, optimized on accurate ab initio calculations, has been built to describe the molecule–membrane interaction, where the molecule is treated as a pseudoatom. The quantum dynamics of the molecules impacting on the membrane along a complete set of incidence directions have been rigorously addressed by means of wave packet calculations in the 3D space, which have allowed us to obtain transmission probabilities and, in turn, permeances, as the thermal average of the molecular flux per unit pressure. The effect of the different incidence directions on the probabilities is analyzed in detail and it is concluded that restricting the simulations to a perpendicular incidence leads to reasonable results. Moreover, it is found that a simple 1D model—using a zero-point energy-corrected interaction potential—provides an excellent agreement with the 3D probailities for perpendicular incidence conditions. Finally, D₂/H₂ and T₂/H₂ selectivities are found to reach maximum values of about 6 and 21 at ≈50 and 45 K, respectively, a feature due to a balance between zero-point energy and tunneling effects in the transport dynamics. Permeances at these temperatures are below recommended values for practical applications, however, at slightly higher temperatures (77 K) they become acceptable while the selectivities preserve promising values, particularly for the separation of tritium.

中文翻译：

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石墨二炔膜分离氢同位素：量子力学研究

Graphdiyne (GDY) 已成为一种非常有前途的用于气体分离技术的二维 (2D) 膜。最具挑战性的目标之一是从具有最丰富的氢同位素 H _{2的混合物中分离氘 (D 2} ) 和氚 (T ₂ ) ，这一成就对于许多工业和科学应用具有重要价值. 在这项工作中，我们研究了氢同位素在通过 GDY 膜的传输过程中的分离，这是由于其固有的亚纳米孔提供的限制增强了质量依赖的量子效应。一个可靠的改进的 Lennard-Jones 力场，在精确的ab initio上进行了优化计算，用于描述分子 - 膜相互作用，其中分子被视为假原子。通过 3D 空间中的波包计算严格解决了沿一组完整入射方向撞击膜的分子的量子动力学，这使我们能够获得传输概率，进而获得磁导率，如热每单位压力的分子通量的平均值。详细分析了不同入射方向对概率的影响，并得出结论，将模拟限制为垂直入射会导致合理的结果。而且，发现一个简单的 1D 模型（使用零点能量校正的相互作用势）与垂直入射条件的 3D 概率提供了极好的一致性。最后，D_发现2 /H ₂和 T ₂ /H ₂选择性在 ≈50 和 45 K 时分别达到约 6 和 21 的最大值，这是由于传输动力学中零点能量和隧道效应之间的平衡而产生的一个特征。在这些温度下的渗透率低于实际应用的推荐值，然而，在稍高的温度 (77 K) 下，它们变得可以接受，而选择性保持有希望的值，特别是对于氚的分离。