Electronic Supplementary Information Conformational isomerism controls collective flexibility in metal-organic framework DUT-8(Ni) Petko St. Petkov, 1,2 Volodymyr Bon, 3 Claire L. Hobday, 4 Agnieszka B. Kuc, 2,5 Patrick Melix, 2,3 Stefan Kaskel, 3 Tina Düren, 4 Thomas Heine 2,3,5 1. University of Sofia, Faculty of Chemistry and Pharmacy, 1126, Sofia, Bulgaria 2. Lehrstuhl für Theoretische Chemie komplexer Systeme, Wilhelm-Ostwald-Institut für Physikalische und Theoretische Chemie, Universität Leipzig, Linnéstr. 2, 04103 Leipzig, Germany 3. Technische Universität Dresden, Fakultät Mathematik und Naturwissenschaften, Fakultät Chemie und Lebensmittelchemie, Bergstraße 66, 01069 Dresden, Germany 4. Centre for Advanced Separations Engineering, Department of Chemical Engineering, University of Bath, Bath BA2 7AY, U.K. 5. Helmholtz-Zentrum Dresden-Rossendorf, Abteilung Ressourcenökologie, Forschungsstelle Leipzig, Permoserstr. 15, 04318 Leipzig, Germany Table of Contents 1. Born-Oppenheimer MD and Well Tempered Metadynamics ........................................... 1 2. Simulated adsorption mechanism ................................................................................... 2 3. Crystallographic details ................................................................................................... 4 4. Figures S1 – S8 ................................................................................................................ 5 5. Tables S1 – S3................................................................................................................ 11 6. References …………………………………………………………………………………………………………………12 1. Born-Oppenheimer MD and well-tempered metadynamics The calculations of periodic models of DUT-8(Ni) MOF were carried out using the QUICKSTEP 1 module of CP2K 2 with a mixed Gaussian and plane waves basis sets. 3 Periodic boundary conditions were applied in all three dimensions. The PBE exchange-correlation functional was used 4 with Goedecker– Teter–Hutter (GTH) pseudopotentials 5 incorporating scalar-relativistic core corrections. The orbital transformation method 6 was employed for an efficient wavefunction optimization. QUICKSTEP, as with nearly all ab initio Density Functional Theory simulation packages, requires the use of a real- space (RS) integration grid to represent certain functions, such as the electron density and the product Gaussian functions. QUICKSTEP uses a multi-grid system for mapping the product Gaussians onto the RS grid(s), so that wide and smooth Gaussian functions are mapped onto a coarser grid than narrow and sharp Gaussians. The electron density is always mapped onto the finest grid. Choosing a fine enough integration grid for a calculation is crucial in obtaining meaningful and accurate results. According to the manual of the code 7 a value of 50 +/- 10 Ry is required for highly accurate results, or for simulations with a variable cell. In our calculations the REL_CUTOFF parameter was set to 60 Ry. Contracted Gaussian basis sets of DZVP quality were used with a grid cutoff of 300 Ry for the BOMD simulations and 360 for the geometry optimization. 8 With this setup for the grid cutoff, 70% of the Gaussian functions are spawned on the finest grid and only 2% on the coarsest. In all calculations Grimme’s DFT-D3 dispersion correction was applied. 9 In our study, a substantial part of the Electronic Supplementary Material (ESI) for Physical Chemistry Chemical Physics. This journal is © the Owner Societies 2018