The physical and electronic properties such as structural geometry, electronic band structure, density of states, and charge density of twenty kinds of two-dimensional hexagonal monolayered alkali halide compounds are studied in this work, where the compounds consist of group IA (alkali metal), and VIIA (halogen) atoms, alkali halide compounds. These materials have been studied by using Vienna Ab initio Simulation Package-VASP program based on first-principles calculations with Density Functional Theory (DFT). The structural properties of these compounds, including crystal shape, lattice symmetry, and the position of atoms are revealed by using crystal figures with top-views and side-views of the geometric structure. Both the wide indirect and direct energy band gaps of all investigated compounds arrange in the range of 3.778 to 6.407 eV, presenting the strong activity of these materials in the ultraviolet (UV) region of the electromagnetic spectrum. Besides, the bonding strength between alkali metal atoms and halide atoms and the electrical conductivity in the materials are also clearly indicated through the charge density diagrams. These properties of two-dimensional hexagonal monolayers of alkali halide compounds are essential for understanding their physical behavior and potential applications in various fields such as optoelectronics and nanotechnology.

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