  We consider a spinless particle moving in a random potential on a
d-dimensional torus. Introducing the gradient of the logarithm of the
wave-function transforms the time independent Schroedinger equation into a
stochastic differential equation with the random potential acting as the
source. Using this as our starting point we write functional integral
representations for the disorder averaged density of states, the two point
correlator of the absolute value of the wave-function as well as the
conductivity for a d-dimensional system. We use the well studied one
dimensional system with Gaussian disorder to illustrate that these quantities
can be computed reliably in the current formalism by using standard
approximation techniques. We also indicate the possibility of including
magnetic fields.
