This variable decides which multipole moments are printed out for
OutputMatrixElements = ks_multipoles:
In 3D, if, for example, OutputMEMultipoles = 1, then the program will print three
files, ks_me_multipoles.x (x=1,2,3), containing
respectively the (1,-1), (1,0) and (1,1) multipole matrix elements
between Kohn-Sham states.
In 2D, this variable is ignored: it will always print two files,
ks_me_multipoles.i (i=1,2), containing the $x$ and
$y$ dipole matrix elements.
In 1D, if, for example, OutputMEMultipoles = 2, the program will print two files, containing the
$x$ and $x^2$ matrix elements between Kohn-Sham states.