Quantum-based materials calculations are considered simulation activities because they involve the application of established fundamental principles derived from mathematical formulations of quantum physics. Here, we study or predict the properties or behavior of materials/systems through calculations using the existing fundamental concepts in quantum mechanics. Performing quantum-based materials calculations does not involve the establishment of new theories; instead, it applies the fundamental theories of quantum physics. People may intuitively have the opposite opinion because they perceive quantum-based materials calculations to involve the development of new theories to study the properties of materials, which is not the case.