Symmetry dictates the physical properties of materials. The symmetry of the Bravais lattice defines the set of points, lines, and planes over which sets of planewaves are degenerate, upon which atomic symmetry determines the interaction potentials which may lift such degeneracies. This results in wavefunctions which are single planewaves throughout the BZ, except in the vicinity of the removed degeneracies. As optical transitions between any two planewaves are forbidden, only regions of the Brillouin zone (BZ) near these lifted degeneracies contribute to optical properties.

Shengbai Zhang,  Professor Emeritus of Rensselaer Polytechnic Institute

APPOINTMENTS

2008-2025/06/30 Professor, Rensselaer Polytechnic Institute, Troy, NY

2008-2025/06/30 Senior Kodosky Constellation Chair, Rensselaer Polytechnic Institute, Troy, NY

2000 -2007 Senior Scientist II, National Renewable Energy Laboratory, Golden, CO

1997-2000 Senior Scientist I, National Renewable Energy Laboratory, Golden, CO

1994-1997 Staff Scientist, National Renewable Energy Laboratory, Golden, CO

1991 - 1994 Research Associate, National Renewable Energy Laboratory, Golden, CO