Dear Emanuele Levi,
It is well known that periodic boundary conditions are a problem for DMRG. You will need a large number of states ( you don't mention how many you use) and you need to sweep often.
Matthias
On Nov 14, 2013, at 10:33, Emanuele Levi emanuele.levi@gmail.com wrote:
Dear ALPS users, I am checking the performance of the DMRG application of ALPS on a simple Ising chain with periodic boundary conditions. The program seems not to be able to converge to the right ground state, even for lengths of the chain such as L=6,8,.. Comparing to the results of the sparsdiag algorithm included in the package the ground state energies are very different.
Does anyone know why it is so? Any idea on how to overcome this problem?
Thank you in advance.
-- Dr Emanuele Levi
emanuele.levi@gmail.com