Dear Alps Team and all Alps users<div><br></div><div>I am trying to recreate results from the paper of Yi-Fei Wang , Zheng-Cheng Gu , Chang-De Gong and D. N. Sheng</div><div>(please see <a href="http://arxiv.org/abs/1103.1686v1" target="_blank">http://arxiv.org/abs/1103.1686v1</a>). I have already implemented a model into xml file and successfully generated </div>

<div>phase diagram for 24 sites checkerboard model (FIG 1 (b)).</div><div><br></div><div>Now I plan to calculate Berry curvature and Chern number (please see the FIG. 3 (c) and paragraph below it).</div><div>And there comes my problem: I&#39;m little confused how to calculate F(θ1 , θ2) [ F(\theta_1,\theta_2) ]. </div>

<div><br></div><div>I have an idea how to calculate differentiation of the eigenvectors numerically and then calculate dot product but I don&#39;t know how to access to eigenvectors from sparsediag.</div><div><br></div><div>

I would be grateful for any advice.</div><div>Best wishes</div><div>Rafał Skolasiński</div>