§Fdalin.d December 19, 2011 [DIALECT Prof. Ver. 1.16] 
Fda program from David J. Heisterberg (1995). 
Script for Windows9x, NT, 2000, XP, Vista, 7 and Linux
(using wine emulator V. 1.x.y) by Ernst Schumacher
Finite Difference program for computation of atomic orbi-
tals and energies of atoms up to g orbital occupation. 
Uses DFT and the Xalpha functional. The model is not
spin polarized and non relativistic.

§Script for configuring and running an Fda job
§Job name
is normally just the IUPAC symbol for the atom you want
to compute. For ions you may add any number of '+' or
'-' signs, e.g. 'Fe+++' or 'S--'. For Z > 110 no symbols
have yet been assigned. We don't use the IUPAC notation
for those: Enter the Z-values '111' to '120' instead.
Restriction: Number of electrons and Z <= 120, so '120-',
'121+' are not accepted, while '119-', '120', '120+' are.

For this job type you may input Z values from 1 to 120 as
'Job name' in addition to the atom symbols. If you enter 
one of these and click [Generate] the ground state electron 
configuration of the neutral atom is automatically entered 
from internal storage and the job is run. Presently atoms 
up to Z = 120 are computed. Electron configurations of 
atoms from about Z = 104 to Z = 120 have not been spectro-
scopically determined. The assignment emulates the period 
above it but takes into account that s-orbitals become 
more stable because of increasing relativistic contri-
butions for the heavier atoms. For atomic ions e.g. 'Ca++',
'16--', or 'Hf++++' the parser chooses the electron con-
figuration of the atoms with as many electrons less or 
more while keeping the Z-value. This is, of course, not 
always correct and less so the higher the (positive) ionic
charge which can cause reshuffling of occupied orbital
sequences. Since atomic ion ground state distributions 
have not been stored inside this little script, some 
'experimentation' is necessary to produce the most stable
electron occupation: Edit the occupation numbers when 
looking at the presented input file and make a number 
of calculations with plausible distributions. E.g. for 
Fe+++ the program suggests, that the energy decreases 
in the sequence [4s2 3d3] > [4s1 3d4] > [3d5], the last 
one being confirmed as the sextet-S groundstate of 
gaseous Fe+++ see [Examples,Tests]. 
In a spin polarized model several other occupations would 
have to be considered.

§[Inp(ut) ready]
If you have an input file 'job'.inp ready, just enter the 
job name (case insensitive) into the 'Job Name' field and 
click [Input ready].

Fill in your (special) electron configuration into the boxes 
of the panel, e.g. to generate ions, atoms with inner excita-
tions (e.g. K edge energies) or different multiplicities 
(note: the model is not spinpolarized!). This mode goes up 
to Krypton. When finished click [Read]. The first two letters
of your job name must be the IUPAC atom symbol.

Fda writes a file documenting the whole calculation along
the number of iterations to selfconsistency. This can be
viewed with [Output]. At the end of the job a summary of
the final results is shown in the editor from where it can
be printed.

Number of radial grid points for integration

§[Plot Density / Orbitals]
At job termination Fda generates a dump file 'job'.dmp con-
taining columns of numbers representing the (nonlinear) steps
of the radius used, the total radial density and all the 
orbitals computed. The latter are normalized and given as 
r*R(r) where R(r) is the radial part of the orbital. Clicking
[Plot Density / Orbitals] calls the graphical window, next.

§Graph Window
Density and orbital information is read in from the dump file 
and can be plotted as soon as the buttons are shown. There
are two formats r·R(r) or R(r) available for plotting the 
radial wavefunctions and their densities (squares). Note, that
only r^2R^2 has shell structure, whereas R^2 alone shows a
monotonically decreasing density for ground states as r->infinity.
The buttons [r-scale -/+] let you change radial axis scale 
down or up, corresponding to 0.25 ... 16 a0. The ordinate is 
automatically scaled but can be increased or decreased by a factor
of 2 a time by clicking [ampl +/-]. The orbitals can be shifted up
(+) or down (-) to see the negative amplitudes better. 
These plots cannot be saved except via image grabber, e.g. 

If you need help with Fda script, email me at 
For information about the fda program: