Computational chemistry for nuclear waste characterization and processing. Relativistic quantum chemistry of actinides

This paper describes some of the motivations and accomplishments of our grand challenge project of the same title and focuses upon the activities at Pacific Northwest National Laboratory. The United States Department of Energy (DOE) funded the project, which finishes this fiscal year. Its objectives were to develop and apply the methods of relativistic quantum chemistry to assists in the understanding and prediction of the chemistry of actinide and lanthanide compounds. This is important to the DOE because the production of nuclear weapons at DOE facilities has left a serious legacy of environmental contamination, including millions of gallons of highly radioactive waste stored in hundreds of tanks that have exceeded their life expectancy. Much of the radioactive waste involves actinides, and their large atomic number implies that relativistic effects have important chemical consequences. By using modern non-relativistic quantum chemistry techniques, it is now possible to calculate to high accuracy the structures, energetics, and properties of molecules containing light elements. Our implementation of relativistic quantum chemical methods will, for the first time on massively parallel computers, provide capabilities for modeling heavy-element compounds similar to those currently available for light-element compounds. (author)