Hi Deepak,

You may be able to get the code to do what you want.  In alps/applications/dmrg/tebd/core/StateOps.f90, starting around line 680, is the place where the internal degrees of freedom are set for the (number conserving) initial state.  As written, the internal state is given by a normalized randomly chosen vector.  However, you can change e.g. line 691 to read Gammas(i)%t(1,j,1)=v(j), where |v(j)|^2 is the probability to measure internal state j at site i.  The ordering of the local basis indexed by j can be sorted out from the number operators if needs be.  Hope this helps.

-Michael

On Mon, Feb 10, 2014 at 3:09 PM, Deepak Iyer <deepak.g.iyer@gmail.com> wrote:

Hi Michael,

Thanks for the quick reply. I see. I guess the magnetic field route is a bit tricky for me - I'm looking for equal populations :) Is there some way I can hack the code - perhaps if you tell me what part of the code deals with this? Or is this very complicated to implement.

Thanks again!
Deepak

On Mon, Feb 10, 2014 at 4:59 PM, Michael Wall <mwall.physics@gmail.com> wrote:

Hi Deepak,

At present, the only way to fix the magnetization in the TEBD code for the Hubbard model is to add a magnetic field.  Otherwise, the magnetization is set as you described.

-Michael

On Mon, Feb 10, 2014 at 2:44 PM, Deepak Iyer <deepak.g.iyer@gmail.com> wrote:

Hi

Is there any way to fix the no. of up and down spins in the TEBD code for the fermion hubbard model? It seems like I'm only allowed to conserve total N and the up and down are randomly assigned and varies from run to run.

Thanks!
Deepak