Ab initio investigations of the interaction of feldspar microcline with water Andrea Conti, Giada Franceschi, Luca Lezuo, Florian Mittendorfer, Michael Schmid and Ulrike Diebold Institute of Applied Physics, Technical University of Vienna, Austria Feldspar microcline (KAlSi 3 O 8 ) is a common mineral in Earth's crust and plays a crucial role as an ice nucleator in atmospheric processes. Understanding its interaction with water is essential for various scientific fields, including geology and climate science. We employed density functional theory (DFT) to investigate different terminations of the feldspar microcline (001) surface and their interactions with water molecules. The metaGGA r 2 SCAN-D3 exchange-correlation functional 1 has been used to obtain the relaxed structures and the adsorption energies of the water molecules. The calculations show that there is a large energy gain from the dissociation of the first water molecule per unit cell and that the reaction proceeds without a barrier. In addition, our results show that the energetically preferred surface termination depends on the environmental conditions, namely the chemical potential of water. We correlate the DFT models with atomic force microscopy (AFM) simulations using the Probe Particle Model 2 to make a comparison with the experimental data imaged in UHV. These simulations enable us to investigate the behaviour of a CuOx tip 3 interacting with the modelled feldspar microcline surfaces under different water coverages. References 1. Ehlert et al. , "r 2 SCAN-D4: Dispersion corrected meta-generalized gradient approximation for general chemical applications", J. Chem. Phys. 154 , 061101 (2021). 2. Hapala et al. , "Mechanism of high-resolution STM/AFM imaging with functionalized tips", Phys. Rev. B 90 , 085421 (2014). 3. Lammers et al. , "Benchmarking atomically defined AFM tips for chemical-selective imaging", Nanoscale 13 , 13617 (2021).
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