Fukuda Jun-Ichi, Yoneya Makoto, Yokoyama Hiroshi
Nanotechnology Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Umezono, Tsukuba 305-8568, Japan.
Phys Rev Lett. 2007 May 4;98(18):187803. doi: 10.1103/PhysRevLett.98.187803.
To account for azimuthal surface anchoring of a nematic liquid crystal, Berreman [Phys. Rev. Lett. 28, 1683 (1972)10.1103/PhysRevLett.28.1683] proposed a simple model attributing the surface anchoring to the elastic distortion of the liquid crystal induced by the grooves of a surface. He showed that the surface anchoring energy is proportional to sin(2)varphi, with varphi being the angle between the director at infinity and the direction of the surface grooves. We argue that his assumption of negligibly small azimuthal distortion of the nematic is not valid. Proper treatment of the azimuthal distortion reveals that the Berreman's model should yield a surface anchoring energy proportional to sin(4)varphi. This implies that surface grooves alone cannot contribute to the surface anchoring coefficient in the usual Rapini-Papoular sense.
为了解释向列型液晶的方位角表面锚定，贝里曼[《物理评论快报》28, 1683 (1972)10.1103/PhysRevLett.28.1683]提出了一个简单模型，将表面锚定归因于由表面沟槽引起的液晶弹性畸变。他表明表面锚定能与sin²φ成正比，其中φ是无穷远处指向矢与表面沟槽方向之间的夹角。我们认为他关于向列型方位角畸变可忽略不计的假设是无效的。对方位角畸变的恰当处理表明，贝里曼模型应给出与sin⁴φ成正比的表面锚定能。这意味着仅表面沟槽不能以通常的拉皮尼 - 帕普洛拉意义对方位角表面锚定系数产生贡献。
