Engines, laptops and power plants generate waste heat. Thermoelectric materials, which convert temperature gradients to electricity and vice versa, can recover some of that heat and improve energy efficiency. A team of scientists at the Department of Energy's Oak Ridge National Laboratory explored the fundamental physics of the world's best thermoelectric material -- tin selenide -- using neutron scattering and computer simulations. Their work may aid energy sustainability and design of materials that convert heat into electricity.