The tricky thing with LDOS for bulk systems is that it is actually a 4-dimensional data object - it's a sequence (over energy) of 3D grids. We haven't implemented any standard export function, although that would be a nice feature enhancement for later! Using a few lines of Python, however, you can easily export the data to any format you prefer.
The simplest approach is if you just want to get LDOS(x,y,z) for a given energy.
(sorry about the formatting, not sure why all the code ends up styled as a comment...)
# Start by reading in the data object
ldos_bulk = nlread("LDOS_Heterostructure_Au&BI2O2Se_Bilayer.hdf5", LocalDensityOfStates)[-1]
# Determine which energy index you want. Either print all the energies and count, or figure it out from the grid you used
print(ldos_bulk.energies())
# Let's assume we want to use the 5th point (counting starts from zero!)
# Verify the energy:
print(ldos_bulk.energies()[4])
# Also need the cell information from the bulk configuration
config = nlread('LDOS_Heterostructure_Au&BI2O2Se_Bilayer.hdf5', BulkConfiguration)[-1]
# Create a GridValues object from the data at this energy and save it:
grid = gridValues(ldos_bulk._data()[4,:,:,:,0], config.bravaisLattice())
nlsave("gridfile.hdf5", grid)
This object can now be visualized separately in NanoLab, and also exported as text data easily using the same function you tried for the LDOS itself.
Note: The last 0 is because the data could in principle be spin-resolved (but is not in your case).
To check you can do
print(ldos_bulk._data().shape)
which would return something like (201, 28, 28, 28, 1) showing that you have 201 energy points, for each of these a 28x28x28 3D grid of data, and 1 spin dimension
For information on the query functions see https://docs.quantumatk.com/manual/Types/LocalDensityOfStates/LocalDensityOfStates.html
Note that the LDOS is internally stored in 1/Bohr**3/Hartree so that will be the unit of the data obtained in this low-level way (we use eV and Angstrom in user-level functions and Hartree and Bohr internally).