No, there is no way to easily do that and it is also not recommended to use periodic boundary conditions with DMRG. You need much more states and convergence is much slower.
On Mar 9, 2013, at 4:14 PM, Emanuele Levi emanuele.levi@gmail.com wrote:
Dear ALPS developers and users, in considering a periodic spin system, is there a way in ALPS to fix the total momentum from the beginning, or measure it?
Many thanks. Kindest regards.
-- Emanuele Levi
emanuele.levi@gmail.com