Hi Dhiman,
Once you create the material from the database:
 You can use the following line of code to look at the list of properties that can be changed:
select("materials::InGaAsP::InGaAsP x=0.5 y=0.5");
?set;
But there is a slight caveat, while setting the properties, you will have two different entities, one for the semiconductor properties (Ct) and the other for the thermal properties (Ht). The script above returns all the properties but while setting their values you need to access them individually. You can select one of them manually and then set their properties using script. But if you want to make it fully script-based then you will have to rename the two objects differently first. Then you can use the set/setnamed command again to set these properties. Here is a quick example:
#Rename the Ct and Ht
select("materials::InGaAsP::InGaAsP x=0.5 y=0.5");
for (i=1:getnumber) {
set("name","InGaAsP x=0.5 y=0.5_"+num2str(i),i);
}
#Set properties of Ctsetnamed("materials::InGaAsP::InGaAsP x=0.5 y=0.5_1","work function",3);
setnamed("materials::InGaAsP::InGaAsP x=0.5 y=0.5_1","dc permittivity",3);
Regards,
Amrita