On May 19, 2015, at 9:18 AM, Thomas SCHMIDT <thomas.schmidt@uni.lu> wrote:

Dear all,

I would like to use the ALPS dmrg routines to simulate the transversal
spin-1/2 XXZ Heisenberg model, i.e., with magnetic field in X-direction.

While a magnetic field in Z-direction [Hz = B*Sz(i)] poses no problems,
a magnetic field in X-direction [Hx = B*(Splus(i) + Sminus(i))] destroys
convergence completely.

I am aware that Hx violates Sz-conservation, but XXZ+Hz is easily solved
by the dmrg package even without assuming conserved quantum numbers, so
I guess conserved quantum numbers are probably not an issue for the
small systems I'm considering (32 sites). Is the bad convergence in the
Hx case something which is expected or do you rather suspect an error in
my configuration?

Thanks a lot! Sincerely,

Thomas
--
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Prof. Dr. Thomas L. Schmidt
Theory of Mesocopic Systems
162a, avenue de la Faïencerie   Phone: (+352) 46 66 44 6158
Université du Luxembourg       Email: thomas.schmidt@uni.lu
L-1511 Luxembourg                  http://www.tlschmidt.com
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