The speaker will begin by discussing the modern concepts of a solid that provide the conceptual basis for the field. Specifically two pictures are presented. In the first, a view of solids as a collection of interacting atoms is used to motivate a reductionist approach where the properties of solids are determined from analyzing atomic structure and the changes undergone in the process of forming solids. The second view is an “emergent approach.” A system is probed, elementary excitations are produced, and then the condensed matter system is described in terms of a response function. The speaker will discuss collective excitations and quasiparticles. He will then go on to describe electronic structure starting with a total Hamiltonian for a solid and then introduce approximations such as the Born-Oppenheimer approximation and the Hartree approximation to reduce the problem to a soluble level. Periodicity, symmetries, Bloch’s theorem, and the like bring the problem to a state where one can solve for energy bands and wave functions. Depending on time constraints, the speaker will give examples of techniques and models that best illustrate the underlying theory.
About the speaker
Marvin Cohen is Professor of the Graduate School at the University of California at Berkeley and Senior Faculty Scientist at the Lawrence Berkeley National Laboratory. His current and past research covers a broad spectrum of subjects in theoretical condensed matter physics. He is a recipient of the US National Medal of Science, the APS Oliver E. Buckley Prize for Solid State Physics, the APS Julius Edgar Lilienfeld Prize, the Foresight Institute Richard P. Feynman Prize in Nanotechnology, and the Technology Pioneer Award from the World Economic Forum along with numerous other honors and a Doctorat Honoris Causa, University of Montreal.
Prof Cohen has contributed more than 750 technical publications. He is a Fellow of the American Physical Society, a member of the US National Academy of Sciences, the American Academy of Arts and Sciences, the American Philosophical Society, and a Fellow of the American Association for the Advancement of Science. In 2005, he was President of the American Physical Society (APS), an organization representing more than 47,000 physicists in universities, industry and national laboratories.
Free and open to the public. Seating is on a first-come first-served basis.
