MPB-DATA(1) MIT Photonic-Bands Package MPB-DATA(1)NAMEmpb-data - transformations of HDF5 files output by MPB
SYNOPSISmpb-data [OPTION]... [HDF5FILE]...
DESCRIPTIONmpb-data is a utility to perform additional processing and transforma‐
tions of HDF5 files output by MPB, the MIT Photonic-Bands program. In
particular, it is designed to make the output more amenable to visual‐
ization by reformatting it into a rectangular grid, extending it to
multiple periods, and rescaling the data.
MIT Photonic Bands (MPB) is a free program to compute the band struc‐
tures (dispersion relations) and electromagnetic modes of periodic
dielectric structures.
HDF5 is a free, portable binary format and supporting library developed
by the National Center for Supercomputing Applications at the Univer‐
sity of Illinois in Urbana-Champaign. A single h5 file can contain
multiple data sets; by default, mpb-data operates on all of the MPB-
produced datasets in the file, but this can be changed via the -d
option, or by using the syntax HDF5FILE:DATASET.
mpb-data writes its output datasets as additional datasets in the input
file(s), with "-new" appended to the dataset names. Alternatively, it
can write its output to a separate file, specified by the -o option.
Note also that, by default, the output datasets are identical to the
input datasets; you must use one or more of the options below to spec‐
ify a transformation (e.g. the -r/-e and -n options are very useful).
OPTIONS-h Display help on the command-line options and usage.
-V Print the version number and copyright info for mpb-data.
-v Verbose output.
-o file
Write output datasets to file (for the first input file only)
rather than as additional datasets in the input file(s) (the
default).
-r Output a rectangular cell with the same volume as the cell of
the input data. This option is particularly useful for visual‐
izing data from non-orthogonal unit cells (e.g. a triangular
lattice), as otherwise the data will appear skewed or warped in
most graphics programs. This option should almost always be
accompanied by the -n option to ensure a uniform resolution.
-e x,y,z
As the -r option, but also make the first axis of the output
along the x,y,z direction (in Cartesian coordinates) instead of
along the first lattice vector as for -r.
-P phaseangle
For complex-valued datasets, this option causes the output val‐
ues to be rotated by phaseangle degrees in the complex plane.
That is, they are multiplied by exp(2 pi i phaseangle / 360).
-n n Output n grid points per lattice unit ("a"). This is useful not
only for interpolating to finer (or coarser) resolutions, but
also to ensure that the resolution is uniform in each direction
(to prevent the data from looking distorted when you visualize
it).
-x mx, -y my, -z mz
This tells mpb-data to output multiple periods in the corre‐
sponding lattice directions. to use a particular slice of a
two- or three-dimensional dataset. e.g. -x 3.2 causes the out‐
put of 3.2 periods in the first lattice direction. The default
is to output only a single period.
-m s Output s periods in each lattice direction; equivalent to: -x s
-y s -z s.
-T The output has the first two dimensions (x and y) transposed.
This is useful in conjunction with the parallel (MPI) version of
MPB, which for performance reasons outputs all arrays with the
first two dimensions transposed. -T can undo this transposi‐
tion.
-p Pixellized output. Normally, the input data is linearly inter‐
polated to the output grid, but the -p option causes it to
instead use the nearest grid point in the input data. This is
useful, for example, if you want to study the discretization of
the dielectric-function representation.
-d name
Use dataset name from the input files; otherwise, the first
dataset from each file is used. Alternatively, use the syntax
HDF5FILE:DATASET, which allows you to specify a different
dataset for each file. You can use the h5ls command (included
with hdf5) to find the names of datasets within a file.
Note that this option is generally unnecessary, since mpb-data
can already find the relevant dataset(s) for files created by
MPB. Also, note that mpb-data treats the dataset specified by
this option as a real scalar dataset and does not include the
exp(ikx) factors when extending the dataset to multiple periods.
BUGS
Send bug reports to S. G. Johnson, stevenj@alum.mit.edu.
AUTHORS
Written by Steven G. Johnson. Copyright (c) 1999-2012 by the Massachu‐
setts Institute of Technology.
SEE ALSOmpb(1)MPB January 27, 2000 MPB-DATA(1)
