For positive values of
NDIMIN, the number of sites in the cluster around each site is
determined as the total number of orbitals in the cluster > NDIMIN.
The number of orbitals on each site is weighted by WSR(tail)/WSR(head).
I. e. NDIMIN < Sum(i) (number of orbitals at site i) 
s(i)/s(j)
for the cluster around site j.
This is not done if NDIMIN=0. The default value is 350.