# Calculate the spin wave dispersion relation for a ferromagnetic heisenberg model

## Homework Statement

Calculate the spin wave dispersion relation Ek for the ferromagnetic heisenberg model with jtot = 1/2
Assume a 1d square lattice and interactions of strength J between nearest neighbours and zero elsewhere

## Homework Equations

H|k> = [E0 +2jtot$\sum J(r)(1-Exp(ik.r)$] |k>

## The Attempt at a Solution

Not really sure where to start :/