where Vp(H) is the volume of a particle having a
diameter Dp(H).
A distribution of anisotropy constants is likely to occur
although a uniform value of K has been assumed in our
calculations. The effect of this assumption is to imply that
the actual switching field distribution (SFD) will be broader
than the particle size distribution. A simple qualitative
consideration of the effect of a distribution of K shows that it
would broaden the overall energy barrier distribution