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\clearance{}
\cache{\days{14}}
\page{
<H1>AtomLab Help</H1>
<P>
<B>Atomlab</B> is a program which solves the Shrödinger equation for an isolated
atom. It takes a small set of parameters as input, and calculates the total energy
and radial distribution density of the system. The default is the setup for Be,
so if you want to know what the calculation looks like, just hit 'Run Program',
and you'll find out what you options are.
</P>
<H3>Input</H3>
<P>
<UL>
<LI><B>E<sub>xc</sub></B><BR>
The type of approximation used for the <I>exchange-correlation</I> energy, as
defined in DFT.
<LI><B>Ionicity</B><BR>
A figure of +1 here means the atom should have a total charge of +1. This is
accomplished by setting the atom number Z to the number of electrons N plus one,
<I>i.e,</I> Z = N+1.
<LI><B>Iterations</B><BR>
To keep the program from running for ever in cases where it has trouble converging.
The default value is reasonable for many systems. <B>Note</B>, however, that you
always must make sure that your system has converged properly, which is easiest done
by checking that the program quits before exceeding the maximum number of iterations.
<LI><B>Mixing</B><BR>
A method-dependent, technical parameter. Here it tells how much, going from one
iteration to the next, of the last tentative configuration should be 'remembered'
when calculating the new tentative configuration.
<LI><B>Electrons</B><BR>
An electron configuration of your choice. For instance, He has the utterly simple
configuration 1s<sup>2</sup>. Be has 1s<sup>2</sup>2s<sup>2</sup>, which is the default.
</UL>
</P>
<H3>Output</H3>
<P>
When running the program, the progress of the calculation is shown on-line in your
browser. After completion, you may optionally download the density distribution.
The file consists of three columns of data: distance, density and zero respectively,
all in appropriate atomic units. The file can be used immediately in for instance
<B>matlab</B>, by the command <B>load</B>.
</P>
<br><br>
}
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