Dear Alps Team and all Alps users

I am trying to recreate results from the paper of Yi-Fei Wang , Zheng-Cheng Gu , Chang-De Gong and D. N. Sheng (please see http://arxiv.org/abs/1103.1686v1). I have already implemented a model into xml file and successfully generated phase diagram for 24 sites checkerboard model (FIG 1 (b)).

Now I plan to calculate Berry curvature and Chern number (please see the FIG. 3 (c) and paragraph below it). And there comes my problem: I'm little confused how to calculate F(θ1 , θ2) [ F(\theta_1,\theta_2) ].

I have an idea how to calculate differentiation of the eigenvectors numerically and then calculate dot product but I don't know how to access to eigenvectors from sparsediag.

I would be grateful for any advice. Best wishes Rafał Skolasiński