Study on the Crystal Structure and Surface Properties of Potassium Feldspar Based on Density Functional Theory

For in−depth research on the crystal structure and physicochemical properties of potassium feldspar, based on the density functional theory calculation method and with the help of the CASTEP module in Materials Studio 8.0 software, the optimal K−point sampling density, cut−off energy and exchange−correlation functionals for the crystal structure calculation of potassium feldspar were determined. The band structure, density of states, Mulliken population, surface energy and differential charge density of potassium feldspar were systematically analyzed.The results demonstrate that near the Fermi level, the electronic density of states is predominantly contributed by the O 2p orbitals. This indicates a high propensity for electron excitation and participation in chemical bonding, identifying oxygen as the most probable active sites for chemisorption processes in potassium feldspar. Mulliken population analysis further elucidates the charge transfer within the crystal lattice, revealing that Al, Si, and K atoms act as electron donors, while O atoms function as electron acceptors.A detailed examination of chemical bonding shows that Si−O and Al−O bonds exhibit strong covalent character and high stability. In contrast, K−O bonds display pronounced ionic characteristics and relatively lower binding strength, making them more susceptible to dissociation. Furthermore, surface energy calculations for different surfaces and differential charge density analysis shows that the (001) surface possesses the lowest energy, indicating its propensity to be exposed as the predominant cleavage plane in natural samples under natural conditions. Moreover, there are three forms of active sites for surface O atoms, namely O atoms in the covalent bonds of Si−O and Al−O, and O atoms formed after the breakage of K−O ionic bonds.Overall, this study systematically unravels the electronic structure and surface properties of potassium feldspar at the atomic level, offering valuable theoretical insights that can guide the understanding of its flotation behavior and support the rational design of effective flotation reagents for mineral processing.