DOI: 10.5061/dryad.2jm63xt1s
title: Data from: Comprehensive first principles study on CO and NO gas adsorption effects on the structural, electronic, and optical properties of ASiSn nanoribbons

description: This paper presents a detailed first-principles investigation of the
 effects of CO and NO gas molecule adsorption on the structural,
 electronic, and optical properties of armchair SiSn nanoribbons
 (ASiSnNRs). Cohesive and adsorption energy calculations indicate that the
 ASiSnNR structure is thermodynamically stable, with physisorption for CO
 (−0.01 eV) and chemisorption for NO (−0.68 eV). Electronic band structure
 analysis reveals that pristine ASiSnNR exhibits semiconducting behavior
 with a narrow band gap (~0.43 eV), which slightly widens upon CO
 adsorption and transitions to a metallic state upon NO adsorption, due to
 strong orbital hybridization and charge transfer effects. Charge density
 and wave function analyses confirm this mechanism, with particular
 emphasis on the role of the π* orbital of the CO molecule. The dielectric
 function, optical absorption, reflection spectra, and joint density of
 states (JDOS) show significant enhancements in anisotropic optical
 properties after CO adsorption, especially in the ultraviolet region.
 These findings suggest the strong potential of ASiSnNRs for selective and
 highly sensitive gas sensing applications, particularly for the detection
 of NO.
description: # Comprehensive first principles study on CO and NO gas adsorption effects
 on the structural, electronic, and optical properties of ASiSn nanoribbons
 DOI: [https://doi.org/10.5061/dryad.2jm63xt1s](https://doi.org/10.5061/dryad.2jm63xt1s) ## Description of the data **INCAR**: The INCAR file is the main control file in VASP that defines how the calculation is performed. It contains parameters such as the energy cutoff (ENCUT), convergence accuracy (EDIFF), ionic relaxation settings (IBRION, ISIF, NSW), and spin treatment (ISPIN, MAGMOM). Each tag specifies how VASP should handle electronic iterations, geometry optimization, and output files. By adjusting these tags, users can switch between relaxation, static, or molecular dynamics calculations. Essentially, INCAR determines the precision and type of simulation. **POSCAR**: The POSCAR file provides the initial atomic structure and lattice information for the simulation. It includes the scaling factor, lattice vectors, element names, number of atoms, and their positions, either in Direct or Cartesian coordinates. This file defines the geometry of the crystal or molecule before any optimization occurs. Its format is straightforward and crucial for ensuring accurate spatial arrangements of atoms. A small change in POSCAR can significantly affect the physical properties obtained from the calculation. **KPOINTS**: The KPOINTS file defines the grid of k-points used to sample the Brillouin zone in reciprocal space. This grid affects the accuracy of electronic structure and total energy calculations. Typically, a Monkhorst-Pack mesh is used, specified by three integers that determine how finely the zone is divided along each lattice vector. The denser the grid, the more accurate but computationally expensive the calculation becomes. Therefore, KPOINTS helps balance precision and efficiency in VASP simulations. **CONTCAR**: The CONTCAR file shares the same format as POSCAR but represents the structure after optimization. It is automatically generated by VASP at the end of a relaxation run. The coordinates in this file show the final atomic positions once the system has reached its minimum energy configuration. Researchers often use CONTCAR as the new POSCAR for subsequent calculations, such as electronic density or band structure analysis. Thus, CONTCAR reflects the equilibrium geometry of the system. These files can be opened and edited with the Notepad program. In VASP calculations, these input files are required.