Returns an automatic Kpoint object based on a structure and a kpoint
        density. Uses Gamma centered meshes always. For GW.

        Algorithm:
            Uses a simple approach scaling the number of divisions along each
            reciprocal lattice vector proportional to its length.

        Args:
            structure:
                Input structure
            kppa:
                Grid density

def automatic_gamma_density(structure, kppa):
        """
        Returns an automatic Kpoint object based on a structure and a kpoint
        density. Uses Gamma centered meshes always. For GW.

        Algorithm:
            Uses a simple approach scaling the number of divisions along each
            reciprocal lattice vector proportional to its length.

        Args:
            structure:
                Input structure
            kppa:
                Grid density
        """

        latt = structure.lattice
        lengths = latt.abc
        ngrid = kppa / structure.num_sites

        mult = (ngrid * lengths[0] * lengths[1] * lengths[2]) ** (1 / 3)
        num_div = [int(round(mult / l)) for l in lengths]

        # ensure that numDiv[i] > 0
        num_div = [i if i > 0 else 1 for i in num_div]

        # VASP documentation recommends to use even grids for n <= 8 and odd
        # grids for n > 8.
        num_div = [i + i % 2 if i <= 8 else i - i % 2 + 1 for i in num_div]

        style = Kpoints.supported_modes.Gamma

        comment = "pymatgen 4.7.6+ generated KPOINTS with grid density = " + \
                  "{} / atom".format(kppa)
        num_kpts = 0
        return Kpoints(comment, num_kpts, style, [num_div], [0, 0, 0])