The E_HOMO, E_LUMO, the HOMO–LUMO gap and gap change of pure and NO₂ or SO₂ on M doped GaNNSs.

Configurations	E HOMO (eV)	E LUMO (eV)	E g (eV)	ΔEg (eV)
GaNNS	−5.75	−3.23	2.52	—
TiGa-GaNNS	−3.76	−3.28	0.47	2.05
TiN-GaNNS	−4.50	−3.60	0.90	1.62
CrGa-GaNNS	−4.28	−3.64	0.64	1.88
CrN-GaNNS	−4.26	−3.78	0.47	2.05
NO2–GaNNS	−5.83	−5.53	0.29	2.23
NO2–TiGa-GaNNS	−5.90	−3.62	2.28	1.81
NO2–TiN-GaNNS	−4.96	−4.01	0.95	0.05
NO2–CrGa-GaNNS	−4.52	−3.87	0.65	0.01
NO2–CrN-GaNNS	−5.08	−4.18	0.91	0.44
SO2–GaNNS	−5.90	−3.37	2.11	0.41
SO2–TiGa-GaNNS	−4.69	−3.29	1.39	0.92
SO2–TiN-GaNNS	−4.59	−3.47	1.11	0.21
SO2–CrGa-GaNNS	−3.45	−2.91	0.53	0.11
SO2–CrN-GaNNS	−3.82	−3.53	0.28	0.19