Scientists call a lot of this work "computational chemistry". Computational chemistry usually uses theoretical chemistry to work on industrial and practical problems. Examples of computational chemistry are projects to approximate chemical measurements such as certain types of post Hartree-Fock, Density Functional Theory, semiempirical methods (such as PM3) or force field methods. Some chemical theorists use statistical mechanics to create a link between the microscopic phenomena of the quantum world and the macroscopic bulk properties of systems.