Let you have the Hamiltonian "-t(i,j)*fermion_hop(i,j) + other terms"
defined on any predefined in "lattices.xml" lattice, where "t" is some
matrix, whose all elements are a priori different. The straightforward way
to define this model is to define the graph with all its edges having
different types. This solution looks fine for several defective bonds. But
if all bonds are different (e.g. you want to optimize the geometry of
kink-like solution of Hubbard-Peierls model), does more elegant way exist on
application level? In any case it is worthwhile to place more comprehensive
answer to this kind of questions in "Tutorials and Documentation/Definition
of models" page.
Kind regards, Andriy Zhugayevych