Physics 240A: Homework Problem Set 6
Due 12/5/07.
1. Density and Density Operator in Many Body Theory. 30 points.
The density operator n(r ) in an N -particle system, and the from of many body wave
function in the Hartree approximation, are given by
N
(r
Physics 240A: Final Exam. 12/12/07
1. Density of States. 15 points.
A two-dimensional material has a relativistic dispersion relation k = |k |. [A currently popular example of such a peculiar system is graphene, a single layer of graphite.]
(a) Calculate,
PHY 240A, Condensed Matter Physics: Solutions to Homework Set #1
1. 2D Honeycomb Lattice. 10 points.
The 2D honeycomb lattice has translation vectors
31
31
a1 = a(
, ); a2 = a(
, )
22
2
2
1
and a basis of two atoms at a( 23 , 0).
(a) Show that the distanc