Density-functional study of defects in two-dimensional circular nematic nanocavities
Density-functional study of defects in two-dimensional circular nematic nanocavities
复制标题
二维圆形向列纳米腔缺陷的密度泛函研究
DOI：
10.1080/02678290903362840
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发表时间：
2009
期刊：
影响因子：
2.2
通讯作者：
E. Velasco
中科院分区：
文献类型：
--
作者：
D. de las Heras;L. Mederos;E. Velasco
我们利用密度泛函理论研究了圆形纳米腔中二维缺陷的结构。密度，有序参数和导演领域，以及缺陷的核心能量和核心半径，得到了在一个物理一致的方式与拓扑电荷k = + 1（径向和切向对称性）和k = + 1/2的缺陷。一个独立的计算的流体弹性常数，在同一理论，使我们能够连接到本地的自由能密度预测的弹性理论，这反过来又提供了一个标准，以定义一个缺陷的核心边界和缺陷的核心自由能的两种类型的缺陷。径向缺陷和切向缺陷具有非常不同的性质，这是以前的Maier-Saupe理论无法解释的特征，因为相互作用的简化性质导致所有弹性常数相等。在腔中有两个k =+1/2缺陷的情况下，由于所考虑的腔的小半径而不能达到弹性状态，但是已经可以获得一些趋势。
We use density-functional theory to study the structure of two-dimensional defects inside a circular nematic nanocavity. The density, nematic order parameter and director fields, as well as the defect core energy and core radius, are obtained in a thermodynamically consistent way for defects with topological charge k = + 1 (with radial and tangential symmetries) and k = + 1/2. An independent calculation of the fluid elastic constants, within the same theory, allows us to connect with the local free-energy density predicted by elastic theory, which in turn provides a criterion to define a defect core boundary and a defect core free energy for the two types of defects. The radial and tangential defects turn out to have very different properties, a feature that a previous Maier–Saupe theory could not account for due to the simplified nature of the interactions, which caused all elastic constants to be equal. In the case with two k = + 1/2 defects in the cavity, the elastic regime cannot be reached due to the small radii of the cavities considered, but some trends can already be obtained.