  The electronic structure of high-quality van der Waals NiPS$_3$ crystals was
studied using near-edge x-ray absorption spectroscopy (NEXAFS) and resonant
photoelectron spectroscopy (ResPES) in combination with density functional
theory (DFT) approach. The experimental spectroscopic methods, being element
specific, allow to discriminate between atomic contributions in the valence and
conduction band density of states and give direct comparison with the results
of DFT calculations. Analysis of the NEXAFS and ResPES data allows to identify
the NiPS$_3$ material as a charge-transfer insulator. Obtained spectroscopic
and theoretical data are very important for the consideration of possible
correlated-electron phenomena in such transition-metal layered materials, where
the interplay between different degrees of freedom for electrons defines their
electronic properties, allowing to understand their optical and transport
properties and to propose further possible applications in electronics,
spintronics and catalysis.
