从内坐标势研究蜂窝晶格的热力学性质：石墨烯和六方氮化硼的情况
Thermomechanical properties of honeycomb lattices from internal-coordinates potentials: the case of graphene and hexagonal boron nitride
摘要：
低维材料中的晶格动力学，特别是弯曲声学模式的二次行为在其热机械性能中起着重要作用。这些的第一原理评估可能是非常苛刻的，并且可能受到破坏平移或旋转不变性的数值噪声的影响。为了克服这些挑战，我们研究了Gartstein内坐标势，并根据石墨烯的第一性原理原子间力常数调整了它的13个参数。我们表明，由此产生的潜力不仅再现非常好的声子分散的石墨烯，但也有任何直径和手性的碳纳米管。增加一个立方项也允许再现占主导地位的非谐项，导致晶格热导率的一个非常好的估计。最后，这种潜在的形式也非常适用于氮化硼，只要它适合于原子间力常数的短程（分析）部分，并在其后增加长程介电贡献。这一考虑强调了基于短程描述符的电位应如何在极性材料中与第一性原理相互作用的短程部分相适应，并由基于相同第一性原理计算参数化的长程分析介电模型进行补充。
英文摘要：
Lattice dynamics in low-dimensional materials and, in particular, the quadratic behaviour of the flexural acoustic modes play a fundamental role in their thermomechanical properties. A first-principles evaluation of these can be very demanding, and can be affected by numerical noise that breaks translational or rotational invariance. In order to overcome these challenges, we study the Gartstein internal-coordinate potential and tune its 13 parameters on the first-principles interatomic force constants for graphene. We show that the resulting potential not only reproduces very well the phonon dispersions of graphene, but also those of carbon nanotubes of any diameter and chirality. The addition of a cubic term allows also to reproduce the dominant anharmonic terms, leading to a very good estimate of the lattice thermal conductivity. Finally, this potential form works very well also for boron nitride, provided it is fitted on the short-range (analytical) part of the interatomic force constants, and augmented thereafter with the long-range dielectric contribution. This consideration underscores how potentials based on short-ranged descriptors should be fit, in polar materials, to the short-range part of the first-principles interactions, and complemented by long-range analytical dielectric models parametrized on the same first-principles calculations.
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