I believe that simulations are an indiscpencible tool for material scientist to use due to it’s many advantages:
A lot of different materials can be constructed in the simulation without having to worry about the cost of the materials;
Experiments that might be dangerous can be performed (Think of making a new material with radioactive substances);
Considering you can potentially make simulations that run faster then real time you can simulate the synthesis of certain materials at a fraction of the time it would take to actually make it (synthesising materials can be very time-consuming in the real world).
However inspite of all these reasons I still believe that real world experiments are indispencible as only these will truly show how a material behaves. Indeed, there can always be an unexpected error in the code used in a simulation that might make the results of the simulation unreliable