materials with very small band gap

[xiangru kong]

Hi, Dominik,

How to set the parameters properly to calculate the topological invariant
of a system with a small band gap?

The band gap is very tiny which is similar to the Silicene (a 2D QSH
insulators with tiny band gap).

Now I have set the parameters (to increase the num_lines) below:

result_0 = z2pack.surface.run(
>
>     system=system,
>
>     surface=lambda s, t: [ s / 2, t, 0],
>
>     num_lines = 201,
>
>     move_tol = 0.3,
>
>     min_neighbour_dist=0.0005,
>
>     save_file = './results/res_0.p',
>
>     load=True
>
> )
>
>
> It seems that the gap checked is always unsuccessful.




>

+----------------------------------------------------------------------+

|                        ==================                            |

|                        CONVERGENCE REPORT                            |

|                        ==================                            |

|                                                                      |

|                        Line Convergence                              |

|                        ================                              |

|                                                                      |

|                            PosCheck                                  |

|                            --------                                  |

|                            PASSED: 337 of 337                        |

|                                                                      |

|                        Surface Convergence                           |

|                        ===================                           |

|                                                                      |

|                            GapCheck                                  |

|                            --------                                  |

|                            PASSED: 336 of 336                        |

|                                                                      |

|                            MoveCheck                                 |

|                            ---------                                 |

|                            PASSED: 335 of 336                        |

|                            FAILED: 1 of 336



Thanks,

Xiangru Kong
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