Computing KS orbitals and saving them to a portable format
Summary: Plotting of KS orbitals in 3D.
Export of the KS orbitals in 3D is a provided by other DFT packages. Currently, it is possible to produce such a data in DenChar utility. However, this is working only with mutually orthogonal unit cell vectors and requires a compilation of the utility.
A good export form would be portable across compilers and operating systems. Possible formats could be Gaussian cube or its equivalent in NetCDF. The grid of points could be the one used in the computation of matrix elements, i.e. accepting the non-diagonal unit cell vectors.
For periodic systems, the lattice-periodic part of the orbital could be plotted.
The input should allow a specification of a set of KS orbitals to be plotted. This could be realized with an FDF-block
%block KohnShamOrbitals3D accepting an energy range specification:
-10, 10 eV and, optionally, a specification of a k-point list on the second, third, etc lines of the block:
%block KohnShamOrbitals3D -10.0 10.0 eV -1.0 1.0 -1.0 0.0 0.0 0.0 %endblock KohnShamOrbitals3D
If the k-points list is missing, then all k-points in the BZ sampling used in SCF would be exported.
To specify the units of the k-points, we could define another option similar to