  This study presents a comprehensive analysis of the band structure in
NiPS$_3$, a van der Waals layered antiferromagnet, utilizing high-resolution
synchrotron-based angle-resolved photoemission spectroscopy (ARPES) and
corroborative density functional theory (DFT) calculations. By tuning the
parameters of the light source, we obtained a very clear and wide energy range
band structure of NiPS$_3$. Comparison with DFT calculations allows for the
identification of the orbital character of the observed bands. Our DFT
calculations perfectly match the experimental results, and no adaptations were
made to the calculations based on the experimental outcomes. The appearance of
novel electronic structure upon alkali metal dosing (AMD) were also obtained in
this ARPES study. Above valence band maximum, structure of conduction bands and
bands from defect states were firstly observed in NiPS$_3$. We provide the
direct determination of the band gap of NiPS$_3$ as 1.3 eV from the band
structure by AMD. In addition, detailed temperature dependent ARPES spectra
were obtained across a range that spans both below and above the N\'eel
transition temperature of NiPS$_3$. We found that the paramagnetic and
antiferromagnetic states have almost identical spectra, indicating the highly
localized nature of Ni $d$ states.
