Nonlocal Density Functional Theory of Molecules and Solids

University Of Pennsylvania, Philadelphia PA

Investigators

Abstract

Jianmin Tao of the University of Pennsylvania is supported by the Chemical Theory, Models and Computational Methods program in the Chemistry Division to develop improved methods for density functional theory (DFT). In the computer-aided design of electronic materials, devices, as well as chemical and physical processes, accurate prediction of electronic properties plays a decisive role. While many wave function-based methods are highly accurate, their computational costs are too expensive to be generally useful for practical applications. For large many-atom systems, DFT is the only method with both the required accuracy and efficiency and for that reason it is the most widely used electronic structure method. However, commonly-used density functionals are unable to achieve universal accuracy. Tao and coworkers focus on developing functionals with a wider range of applicability. These functionals are being used to study the properties of diverse systems such as (water) clusters and light-emitting oligomers and polymers. The work involves both method development and numerical application. The project also includes summer outreach programs aimed primarily at undergraduates. The goal of this research project is the development and application of nonlocal density functionals (DFT), including a new nonlocal correlation energy functional for long-range van der Waals interactions. The focus of this effort is on solving or mitigating some long-standing difficulties that commonly-used density functionals encounter. A major outstanding problem for DFT methodology is that a density functional may be accurate for one or more classes of systems, but not for all systems, or for one or more properties, but not for all properties. A goal of this project is to develop a density functional with universal accuracy and wider applicability so that diverse chemical and physical problems can be solved on the same footing, with the same density functional. Such a density functional must be nonlocal, because the nature of the Coulomb interaction is nonlocal. Undergraduates, graduate students and postdocs are involved in various aspects of this project.