X-ray electron density investigation of chemical bonding in van der Waals materials

Hidetaka Kasai, Kasper Tolborg, Mattia Sist, Jiawei Zhang, Venkatesha R. Hathwar, Mette Filsø, Simone Cenedese, Kunihisa Sugimoto, Jacob Overgaard, Eiji Nishibori, Bo B. Iversen*

*Corresponding author for this work

Research output: Contribution to journal/Conference contribution in journal/Contribution to newspaperJournal articleResearchpeer-review


Van der Waals (vdW) solids have attracted great attention ever since the discovery of graphene, with the essential feature being the weak chemical bonding across the vdW gap. The nature of these weak interactions is decisive for many extraordinary properties, but it is a strong challenge for current theory to accurately model long-range electron correlations. Here we use synchrotron X-ray diffraction data to precisely determine the electron density in the archetypal vdW solid, TiS2, and compare the results with density functional theory calculations. Quantitative agreement is observed for the chemical bonding description in the covalent TiS2 slabs, but significant differences are identified for the interactions across the gap, with experiment revealing more electron deformation than theory. The present data provide an experimental benchmark for testing theoretical models of weak chemical bonding.

Original languageEnglish
JournalNature Materials
Pages (from-to)249-252
Number of pages4
Publication statusPublished - 26 Feb 2018


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