Subject: Re: CCL:Integrating electron densities

From: [email-masked] (Ross M. Dickson)
Date: Thu, 28 Jul 1994 09:58:20 -0600

Frank De Proft ([email-masked]) asked,

>Does anyone know of any programs integrating atomic electron densities
>numerically starting from a grid of points ?

I note that this is the second time he's asked this, so I thought someone
should reply.

I'm sorry I don't have any software available to so this instantly.  My
impression is that this is an old and thoroughly solved problem, but I
don't have references handy on exactly who solved it how and when.  For
spherical atoms all you need is a one-dimensional numerical integration,
which is well-covered in standard references such as "Numerical
Recipes" by Press, Flannery, Teukolsky and Vetterling.  I don't think
nonspherical atoms are that much more complicated, but then polyatomic
molecules are my thing.  If you want an example of a general 3-D
integration scheme that would be suitable for atomic densities among
other things, see A.D. Becke, J.Chem.Phys. 88(4) 2547 (1988).

While conciseness is generally a Good Thing in posting to mailing lists
such as this one, it is worth mentioning that it is possible to be too
concise.  Since this is a group of interested individuals and not of
servicepeople waiting to solve every problem that comes by, it is often
good to provide a little background about your question, if for no
other reason than to get your reader and potential helper interested.
Good things to mention are why you need a thing and where you have
already looked for it, for example.  Without this information, it's
very easy for the reader to think "Oh, he can solve that problem just
by going down to the library and looking in Chem. Abs.," or "Oh, she
can solve that problem just by doing a little basic math," in which
case no reply will be generated since the readers are busy with more
interesting (to them) things.

Cheers,
Ross M. Dickson  ([email-masked])

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From: [email-masked] (Ross M. Dickson)
Date: Thu, 28 Jul 1994 09:58:20 -0600

Cheers,