Dear Hamid, You can use complex numbers in the ALPS applications. Usually you need to set the parameter: COMPLEX=1 Then you can use “I” (capitol “i”) to define an imaginary number, e.g. J=1+2*I The evaluation of observable should also work fine. Best regards, Michele -- ETH Zurich Michele Dolfi Institute for Theoretical Physics HIT G 32.4 Wolfgang-Pauli-Str. 27 8093 Zurich Switzerland dolfim@phys.ethz.ch www.itp.phys.ethz.ch +41 44 633 78 56 phone +41 44 633 11 15 fax

On Sep 3, 2015, at 3:32 PM, hamid mosadegh <hamid.mosadegh@gmail.com> wrote:

Dear All,

Is it possible to add imaginary term to Hamiltonian in DMRG calculations or evaluate the expectation value of a operator with imaginary part.

Thanks

-- H. Mosadeq Shahr-e-Kord University (SKU), Shahr-e-Kord , Iran