*主持人：叶东 教授

*讲座内容简介：

While the hexagonal lattice is ubiquitous in two dimensions, the body centered cubic lattice and the face centered cubic lattice are both commonly observed in three dimensions. A geometric variational problem motivated by the diblock copolymer theory consists of a short range interaction energy and a long range interaction energy. In three dimensions, and when the long range interaction is given by the nonlocal operator $(-\Delta)^{-3/2}$, it is proved that the body centered cubic lattice is the preferred structure.

*主讲人简介：

任晓锋，乔治华盛顿大学教授，1994年在Minnesota大学获得博士学位，师从倪维明教授。主要从事几何变分、偏微分方程、材料力学、生物数学等领域的研究。在Comm. Math. Phys, Arch. Ration. Mech. Anal, Trans. Amer. Math. Soc等国际一流学术期刊上发表学术论文60余篇，被引用超过1500次。