Department of Microtechnology and Nanoscience, MC2, Chalmers University of Technology, SE-41296 Göteborg, Sweden.
J Chem Phys. 2010 Apr 7;132(13):134705. doi: 10.1063/1.3366652.
In this paper, we show that first-principle calculations using a van der Waals density functional (vdW-DF) [M. Dion, H. Rydberg, E. Schroder, D. C. Langreth, and B. I. Lundqvist, Phys. Rev. Lett. 92, 246401 (2004)] permit the determination of molecular crystal structure within density functional theory (DFT). We study the crystal structures of hexamine and the platonic hydrocarbons (cubane and dodecahedrane). The calculated lattice parameters and cohesion energy agree well with experiments. Further, we examine the asymptotic accounts of the van der Waals forces by comparing full vdW-DF with asymptotic atom-based pair potentials extracted from vdW-DF. The character of the binding differs in the two cases, with vdW-DF giving a significant enhancement at intermediate and relevant binding separations. We analyze consequences of this result for methods such as DFT-D and question DFT-D's transferability over the full range of separations.
在本文中，我们展示了使用范德华密度泛函（vdW-DF）[M. Dion，H. Rydberg，E. Schroder，D. C. Langreth 和 B. I. Lundqvist，Phys. Rev. Lett. 92, 246401（2004）]的第一性原理计算可以在密度泛函理论（DFT）中确定分子晶体结构。我们研究了己六胺和柏拉图烃（立方烷和十二烷）的晶体结构。计算得到的晶格参数和内聚能与实验值吻合较好。此外，我们通过比较全 vdW-DF 与从 vdW-DF 中提取的渐近原子对势来检验范德华力的渐近描述。在这两种情况下，结合的性质不同，在中间和相关的结合分离中，vdW-DF 给出了显著的增强。我们分析了这一结果对 DFT-D 等方法的影响，并对 DFT-D 在整个分离范围内的可转移性提出了质疑。
