**Theoretical chemistry: Electronic structure on the border between wavefunctions and density functional theory**21 March - 21 September 2019

**Biography**

Kieron Burke is a professor in both the chemistry and physics departments at UC Irvine. His research focusses on developing a theory of quantum mechanics called density functional theory.

Density functional theory (DFT) is a way of solving the equations of quantum mechanics for the electrons in any substance. Because DFT equations can be solved relatively quickly on modern computers, DFT has become a very popular tool in many branches of science, especially chemistry and materials science. Last year, at least 30,000 scientific papers used DFT. For example, hydrogen sulphide was predicted by DFT calculations to have a high superconducting temperature under pressure, and a year later, it was tested and became the world-record holder, at 203 K (−70° C).

Prof Burke works on developing all aspects of DFT: formalism, extensions to new areas, new approximations, and simplifications. His work is heavily used in materials science, chemistry, matter under extreme conditions (such as planetary interiors or fusion reactors), magnetic materials, molecular electronics, and so on. He has given talks in theoretical chemistry, condensed matter physics, applied mathematics, and even organic chemistry. His graduate students and postdocs usually come from either chemistry or physics departments, but his undergraduate researchers also come from math, computer science, and engineering. He also runs an internship program for motivated high-school students.

Kieron Burke is a Chancellor's Professor of UC Irvine, and a fellow of the American Physical Society. He is known around the world for his many educational and outreach activities. Recently, he was honored to participate in the Baker symposium at Cornell in 2016, he was named the 2017 Bourke Lecturer by the Royal Society of Chemistry, and elected a member of the International Academy of Quantum Molecular Scientists. According to google scholar, his research papers are now cited more than 13,000 times each year.

**Project Summary**

A key branch of modern theoretical chemistry is called electronic structure theory, which develops methods for solving the quantum mechanics of electrons, thereby allowing the prediction of energies and geometries of molecules using a computer. Because density functional theory (DFT) can be solved relatively quickly on modern computers, it has become a very popular tool in many branches of science, especially chemistry and materials science. Last year, at least 30,000 scientific papers described new insights gained using DFT. For example, hydrogen sulphide was predicted by DFT calculations to have a high superconducting temperature under pressure, and a year later, it was tested and became the world-record holder, at 203 K (−70°C).

But DFT requires users to make uncontrolled approximations to a mysterious, unknown quantity, called the exchange-correlation energy, and the quality of DFT results is determined by the quality of this approximation. There are many molecules and materials of tremendous technological importance for which DFT is either inaccurate or fails entirely. Many materials vital for energy applications (e.g. batteries, solar cells, etc.) are oxides, for which current DFT approximations have problems.

*Ab inito* quantum chemistry is a systematic, controlled approach to solving the Schrödinger equation, and gives almost exact results for many molecules, but remain challenging for examples involving strong correlation. It plays a crucial role in benchmarking DFT approximations, demonstrating that DFT methods can have useful accuracy for many molecules. Prof Burke has developed some of the most popular approximations in DFT, while Prof Manby is a leading developer in the world of ab initio quantum chemistry. Both have a keen interest in improving DFT methods, and making them more systematic. The envisioned outcomes of this Fellowship would be the generation of more accurate and more general density functionals, and a better understanding of DFT in terms of ab initio quantum chemistry.

During his stay in Bristol Professor Burke will be hosted by **Professor Fred Manby **(Chemistry)

**Events:**

- Departmental Seminar - Wednesday 26th June, 2 pm

Berry Theatre, 3.21 Physics

*The semicclassical origins of density functional approximations*

Each year, at least 40,000 scientific papers in many different areas report modern density functional calculations of electronic structure. In this seminar, Professor Burke will explain how the approximations used in DFT are in fact semiclassical approximations of an unusual kind, and some recent work in this area.

All welcome

- Public Lecture - Wednesday 21st August, 3 pm

Chemistry, Lecture Theatre 4

followed by a reception in East Foyer

*How understanding quantum mechanics might save our planet*

Each year, at least 40,000 scientific papers use electronic structure calculations to better understand molecules and materials, and to predict new ones with useful properties. These calculations solve the equations of quantum mechanics for the electrons. Applications range from finding new catalysts and new superconductors to understanding planetary interiors and climate change.

Professor Burke will attempt to explain both the science and the sociology of this subject. This is a talk aimed at a general audience with an interest in science and that cares about the future of our planet. It touches on chemistry, physics, mathematics, engineering, and computer science.

All welcome

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