Hi All,<br><br>I want to calculate energy gap for spin chain with DMRG. I set NUM_EIGENVALUES=2 in my parm file but the result which  achieved is wrong.<br>Is it necessary to determine something else for example the sector which DMRG work in it? in my problem I dont have any good symmetry and I can not easily determine the sector which the first exited state is in it. I would be very appreciate if someone could please help me.<br>
<br>Thanks,<br>Zhian.<br>