[ALPS-users] Complex hopping intensity on some graph

Hi,

I introduced complex hopping parameter as follows (in the models.xml file):

<BONDOPERATOR name="fermion_hop_l" source="x" target="y"> cdag_up(x)*c_up(y)+cdag_down(x)*c_down(y) </BONDOPERATOR>

<BONDOPERATOR name="fermion_hop_r" source="x" target="y"> cdag_up(y)*c_up(x)+cdag_down(y)*c_down(x) </BONDOPERATOR>

and later, as a bound term,

<BONDTERM source="i" target="j"> <PARAMETER name="tl#" default="0"/> <PARAMETER name="tr#" default="0"/> -tl#*fermion_hop_l(i,j) -tr#*fermion_hop_r(i,j) </BONDTERM>

In the parameters file, I put tr=tl*, so it seems to me, that such definition always lead to hermitian matrix, and do not depend on lattice\graph. Nevertheless, it does not work on a graph ('can not convert complex number into real one' error) but does work on predefined square lattice.

What is the problem? Is the definition of the Hamiltonian is correct?

Thank you in advance, Volodymyr Derzhko