  The electronic structure of monolayer pentagonal palladium diselenide (PdSe2)
is analyzed from the topological band theory perspective. Employing
first-principles calculations, effective models and symmetry indicators, we
find that the low-lying conduction bands are topologically nontrivial,
protected by time reversal and crystalline symmetries. Numerical evidence
supporting the nontrivial character of the bands is presented. Furthermore, we
obtain a relevant physical response from the topological viewpoint, such as the
spin Hall conductivity.
