Table 4.

Static dielectric constant ${\epsilon }_1(0)$ , peak values of imaginary part ${\epsilon }_2(\omega )$ for monolayer CSe with and without doping.

Doped Atoms X	Concentration (%)	${\mathit{\epsilon }}_{1\mathit{x}\mathit{y}}(0)$	Peak Positions (eV)
-	0.00	${\epsilon }_{1xy}(0)=3.0973$	A = 4.19
-	-	${\epsilon }_{1z}(0)=1.9475$	B = 5.55
-	-	-	C = 7.15
-	-	-	D = 9.00
S	1.56	${\epsilon }_{1xy}(0)=3.1277$	A = 4.157
-	-	${\epsilon }_{1z}(0)=1.9551$	B = 5.58
-	-	-	C = 6.62
-	-	-	D = 9.25
S	2.78	${\epsilon }_{1xy}(0)=3.1196$	A = 3.796
-	-	${\epsilon }_{1z}(0)=1.9187$	B = 5.51
-	-	-	C = 6.57
-	-	-	D = 9.225
S	6.25	${\epsilon }_{1xy}(0)=3.2257$	A = 4.16
-	-	${\epsilon }_{1z}(0)=1.9957$	B = 5.42
-	-	-	C = 7.60
-	-	-	D = 9.20
O	6.25	${\epsilon }_{1xy}(0)=3.1767$	A = 3.81
-	-	${\epsilon }_{1z}(0)=1.9803$	B = 4.73
-	-	-	C = 6.43
-	-	-	D = 9.298
Te	6.25	${\epsilon }_{1xy}(0)=3.3783$	A = 3.96
-	-	${\epsilon }_{1z}(0)=2.098$	B = 5.54
-	-	-	C = 6.68
-	-	-	D = 9.163