On Dec 4, 2010, at 8:46 AM, Martin Hohenadler wrote:
Dear all,
I was trying to specify the number of eigenvalues calculated by sparsediag, using
NUMBER_EIGENVALUES=1
as described here: http://alps.comp-phys.org/mediawiki/index.php/Documentation:sparsediag
However, sparsediag nevertheless calculates the lowest eigenvalue for each wavevector.
NUMBER_EIGENVALUES specifies the number of eigenvalues that should be calculated in each symmetry sector. If you don't want that then you can set the value of TOTAL_MOMENTUM to restrict the calculation to one momentum sector.
A second question pertains to the output of sparsediag. With the above input file, the results contain the line
<PARAMETER name="TOTAL_MOMENTUM">5.7595865315812870833</PARAMETER>
This is because it uses translational symmetry and diagonalizes the Hamiltonian in each symmetry sector, looping over all values of TOTAL_MOMENTUM.
Matthias