Dear Hamid,

Sorry for the late reply, I hope this might still be useful to you.

We have recently introduced a new dmrg code called mps_optim which is able to compute the entanglement spectrum at some given site.

I'm attaching an example on how to use it, since this is an "undocumented feature". To try it out somply execute: alpspython spin_spectrum.py

Note that you need a recent version of ALPS, I would suggest to install the /trunk version that you can obtain from: (no binaries are available at the moment, you should compile the code yourself) svn co https://alps.comp-phys.org/svn/alps1/trunk/alps

Best regards, Michele

On 16.12.2014 14:37, hamid mosadegh wrote:

Dear ALPS user

I want to calculate the left reduced density matrix \rho_L=Tr_R |\Phi><\Phi| using DMRG and then evaluate the entanglement spectrum consists of the energies of the entanglement Hamiltonian H_E=-Ln(\rho_L)

But we don't have direct access to the many body wave function in the DMRG calculations using ALPS.

Is there any way to evaluate these parameters in the DMRG calculations using ALPS?

Thanks

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