Table 3.

Static real part of dielectric function ${\epsilon }_1(0)$and static refractive index n(0) of orthorhombic bulk and surface of CsPbBr${}_3$.

Structure	${\epsilon }_1(0)$			n(0)
	${\epsilon }_1^x(0)$	${\epsilon }_1^y(0)$	${\epsilon }_1^z(0)$	$n^x(0)$	$n^y(0)$	$n^z(0)$
Bulk	1.720	1.720	1.800	1.300	1.300	1.320
Surface	1.100	1.100	1.060	1.045	1.045	1.040