First-principles dataset on few-layer As2S3: structure, phonons, and nonlinear optical response

This dataset contains all computational data produced by exploring how layer-dependent inversion symmetry and in-plane anisotropy govern the evolution of the electronic, vibrational, and nonlinear optical (NLO) properties of arsenic trisulphide (As2S3) from bulk to monolayer form.

All data were obtained from first-principles calculations performed with the CRYSTAL code (https://www.crystal.unito.it) at the B3LYP-D3 and HSE06-D3 levels of theory. The dataset includes structural models, phonon dispersions, Raman and infrared spectra, electronic band structures, density of states, effective masses, and electron localisation functions (ELF). The nonlinear optical response was evaluated through the first- and second-hyperpolarizability tensors (β and γ).

Data are organised into thematic folders:
/basis_sets - Gaussian-type orbitals basis sets employed throughout the simulations.
/structures - Optimised geometries of the models (CIF and CRYSTAL input/output).
/electronic_structure - Band structures, DOS/PDOS.
/effective_masses - Electron and hole effective masses extracted from curvature analysis along principal in-plane directions.
/phonon_structure - Phonon dispersions and dynamical matrices, phonon band structures and density of states.
/Raman_IR — Simulated Raman and infrared spectra.
/SCF — Self-consistent-field outputs and total energies.
/ELF — Electron localisation function (3D format).

Each directory contains a dedicated README.md file describing the included data, input parameters, and units. All files follow the FAIR principles (Findable, Accessible, Interoperable, Reusable).

These data provide a complete computational benchmark for understanding symmetry-dependent quantum confinement and anisotropic light–matter coupling in low-dimensional metalloids. They can serve as a reference for future studies on related systems, and as a basis for validating experimental Raman, optical, or ultrafast measurements.