# Fermi surface explorer

## Enjoy the beauty of Fermi surfaces and get information about the electrons!

Fermi surfaces, Fermi velocities and character of the electronic states at the
Fermi surfaces are visualized based on ab initio
electronic structure calculations within a scalar-relativistic
or fully relativistic optimized LCAO scheme for the light and heavy
elements, respectively [1,2]. All highlighted metals in the periodic
system are available at the moment. The systems are considered in the given
crystal structure. In case of multi-sheeted Fermi surfaces the sheets
are presented separately. For magnetic materials majority and minority
sheets are given.

Another option is the Fermi velocity of the electrons.
The velocity at the Fermi surface is indicated by continuously changing
colors from low velocity states (blue) to high velocity states (red).

Finally, the character of the electronic states is analyzed. For this
purpose an angular momentum expansion of the Bloch functions is used.
The square of the expansion coefficients is a measure for the character
of the states. For zero expansion coefficients (blue) the considered
angular momentum component is absent. For expansion coefficients equal
to one (yellow) the considered character dominates. In between is a
continuous transition.

An easy introduction to the figures is given in [3].
Numerical details of the visualization are discussed in [4].

[1] H. Eschrig, Optimized LCAO Method and the Electronic Structure of Extended Systems, Akademie-Verlag Berlin (1988)

[2] M. Richter and H. Eschrig, Solid State Communications **72**, 263 (1989)

[3] C. Lehmann, Staatsexamensarbeit, TU Dresden (1997) (in German)

[4] P. Zahn, Diplomarbeit, TU Dresden (1994) (in German)

This work was done at
Institut für Theoretische Physik at
TU Dresden.

by C. Lehmann, S. Sinning,
P. Zahn,
H. Wonn,
I. Mertig,
Dresden 1996-1998

technical realization by
J. Bergmann († 2010),
M. Zahn.