SESSION 3: MECHANICAL, THERMAL, AND CHEMICAL STABILITY OF MOFS
Beyond Periodic Boundary Conditions: Thermal Opening of MOF Nanoparticles
Ruhr-University Bochum, Computational Materials Chemistry group, Bochum, Germany
Keywords: pillared layer MOFs, force field simulations, phase transition
By adding flexible chains to the linkers, pillared layer MOFs can be converted to breathing and gating systems. For the theoretical investigation of stimuli induced phase transitions it is advantageous to focus on the temperature induced opening of such systems. Here no grand canonical system with a changing number of guest molecules needs to be simulated, as it would be the case for adsorption induced transformations. Previously we have used our first-principles parameterized force field MOF-FF[1] to investigate this process within periodic boundary conditions[2]. However, in reality an interface between phases can form, which is only to be realized in a simulation system ofvery large size, or, ideally, without the artificial constraint of periodic boundary conditions for a nanoparticle.In the presentation a revised MOF-FF for these systems will be presented, based on a force matching for the flexible side chains. By extending the numerically efficient lammps code with the potential terms necessary for MOF-FF substantially larger systems can now be investigated. Our first results on the thermal opening of nanoparticles of different size will be discussed.
Figure 1: Opening of a 6x6x6 BME-fu-MOF nanoparticle (Cu(BME-bdc)2(dabco), BME-bdc: 2,5-bismethoxyethoxy-benzenedicarboxylate) by heating from 300K to 500K.
[1] S. Bureekaew, S. Amirjalayer, M. Tafipolsky, C. Spickermann, T. K. Roy, R. Schmid, Phys. Stat. Sol. B, 250, 1128-1141, 2013
[2] M. Alaghemandi, R. Schmid, J. Phys. Chem. C, 120, 6835-6841, 2016