ELEMENTS: Anharmonic formalism and codes to calculate thermal transport and phase change from first-principles calculations

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Most properties of crystalline materials can today be calculated with a high degree of accuracy via computation. Due to the nature of the physical theories, these properties are, however, currently calculated at absolute zero temperature. The purpose of this project is to develop methodologies and computer codes to extend the calculation of elastic and thermodynamic properties to temperatures as high as 1000C or more, where thermal expansion becomes important and structural phase transitions can occur. This work can have a great impact in the aerospace and car industries, which make engines and parts operating at very high temperatures. The tools we will develop enable accurate prediction of stability and thermophysical properties of materials, even if they have not been synthesized in the lab. The results of these calculations will also be included in materials databases and help in our understanding of the behavior of new functional materials. These tools will be freely available to the research community under an open source license so as to engage the community in further development and collaboration. During this project a postdoctoral researcher and a graduate student will be trained in computing, data processing and storage methods. We will also develop modules to teach K-12 students about energy, its conversion, storage and sustainability during summer projects organized by the project lead.The mission of the proposed project is to provide to the materials physics community tools based on a new generation of quantum mechanical methodologies and input from first-principles calculations, to enable advances in two challenging areas: (1) thermodynamic, dielectric, mechanical and thermal transport properties at high temperatures where anharmonic effects become important, and (2) prediction of solid-solid phase transitions as a function of temperature, particularly in multifunctional materials, in which phonons are coupled to electronic degrees of freedom. This approach will be systematic, and applies to real materials enabling quantitative prediction of the above properties. The codes will be tested and validated on non-trivial materials such as transition metal oxides (TMOs) due to those materials having a rich number of phase transitions and emergent multiferroic phases. These materials and their applications in energy and information storage and processing also have a large amount of experimental and theoretical data on their phase transitions available, for validation. In summary, these timely tools will enable materials scientists to predict or understand thermophysical properties of anharmonic, complex and multifunctional materials at arbitrary temperatures with unprecedented accuracy.This project is funded by the Office of Advanced Cyberinfrastructure in the Directorate for Computer and Information Science and Engineering, with the Division of Materials Research in the Directorate for Mathematical and Physical Sciences also contributing funds.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.