Firstly you have to define:

region num=xxx  y.min=...    user.material=CZTS

Then you must define the properties:

material region=yyy material=CZTS user.group=insulator (or what it is)  user.default=oxide (or closer) permittivity=3.5

Or for semiconductor much more parameters. For intance:

material region=yyy material=CZTS user.group=semiconductor user.default=PPV eg300=1.09 nc300=2.5e19 nv300=1.04e19 permittivity=11.8 taun0=1e-9 taup0=1e-9 affinity=2.8

Then continue with statement (see example):

mobility region=yyy material=CZTS deltaen.pfmob=0.48 deltaep.pfmob=0.48 betan.pfmob=3.7e-7 betap.pfmob=3.7e-7 mun=0.5e+2 mup=0.5e+2

Then in models statement you need to select the proper model.

Good luck !

I have the same problem to define InAsBi and InAsSb in atlas, i used your method Mr Cristtian Ravariu but an warning appeared :" no default material  dpecifed for user material :"InGaBi" setting Silicon as default!! there is no another way to solve this problem please