The code FDA for atomic orbitals

Presentation

The code is developped within the same manner as for the herman-skilman code. It allows to calculate energies and orbitals of atoms for any electron configuration we fancy: Atoms in groundstate, atomic ions, ionization potentials, electron affinities, inner excitations for X-ray terms, outer excitations for UV/VIS spectra. It is written in C/C++ and can be compiled e.g. with Visual C/C++, 6.0. The authors have compiled the program, bundled it with the script fdalin and test examples.

 Notice: The model is not spin polarized and non relativistic. Overall, it has an accuracy between LDA (local density approximation) and LSD (local spin density approximation). The following pictures from NIST show the accuracy of these and other DFT methods across the PS for ionization potentials and the expected corrections of the atomic energies resulting from spin polarization.

To download the code click on the following link:

http://www.chemsoft.ch/downloads/fdalin.zip


The code has a graphical interface called FDALIN developped by E. Schumacher.

 

Clicking the buttons [FDA] and [fdalin] in the top menu bar of the panel gives us a short introduction by David J. Heisterberg's FDA and to some examples of using this script. FDA is freeware but must carry Heisterberg's copyright.

Installation

To install this graphical interface we need to install the wine emulator on linux
 (we present commands related to opensuse system, you deduce commands for other linux systems).

NB:  Wine is a free and open-source compatibility layer that aims to allow computer programs developed for Microsoft Windows to run on Unix-like operating systems. Wine also provides a software library, known as Winelib, against which developers can compile Windows applications to help port them to Unix-like systems.

> sudo zypper install wine

Now we need to execute the graphical interface:

> chmod +x fda
> ./fda


Execution

Before the execution of the code, we need to learn the function of every button of the GUI interface through the following link:

http://www.chemsoft.ch/qc/expl.htm

We can fill the boxes for composing a special electron configuration and run it with [Read], or use [Generate] with an atom symbol to refer to the stored ground state configurations (which can be edited before computing). [Inp(ut) ready] lets us run a previously generated input file.
The density and orbital arrays can be plotted with [Plot Density/Orbitals] (see below).

The fdalin script from Ernst Schumacher, U. of Bern, lets us easily compose an input file for FDA according to the conventions set up by Heisterberg, runs that input, and produces two outputfiles and several types of density and orbital plots.

There are no traces of any further work of David Heisterberg with FDA and its development on the web (as of 2010).

Example of atom Zn

- In the box job name we put Zn
- We click on the button generate to create the electronic configuration of the atom.
-  We click on the button Output to get the results.
- Click on the Plot Density/Orbitals to plot density and orbitals of the atom.

we select the H.dmp file where the information about the data to be plotted are stored as it's shown in the following picture:

The following picture is of the orbitals of Zn atom.

We compare the result with that obtained by the herman-skilman code.

Reference: http://www.chemsoft.ch/qc/fda.htm