Subject: Re: CCL:DeFT and 3rd row elements.

From: [email-masked] (Alain St-Amant)
Date: Fri, 5 Sep 1997 11:37:51 -0400

>        Concerning elements other than 2nd row atoms (Li-Ne) I've converted 
>the DGAUSS basis sets found in the CCL archive. DeFT seems to explicitly 
>need also the XC auxiliary basis set which misses in the DGAUSS or other 
>distributions. I've set the coefficients in the XC basis sets equal to 
>1/3 the ones of the density auxiliary basis set. I've done this after 
>inspecting the XC coefficients in the original DeFT basis set 
>distribution. It seemed an undeclared rule. After doing this I've found 
>that basis sets for most elements (others than Li-Ne) are archived at
>ftp://ftp.caos.kun.nl/pub/misc/deft/
>The XC auxiliary bs are also given in this distribution and are as those 
>I computed. 
>        So I'm curious to know how did you managed to get the XC aux. bs.

Hi,

At the time I released the current version, only the basis sets up to neon
were published.  Since then, Cray has released the entire DGAUSS basis sets.
A future release of the code will come soon (I'm trying to improve the
convergence of the SCF and geometry optimizations, and I've focussed on
efficient parallelization).  As always, it'll be freely distributed over the
Net.

You are right in cutting the exponents by a factor of three.  Since the
XC potential roughly goes as rho**(1/3), and the final results are really
insensitive to the exact value of the exponents, this simple approach is
more than adequate.

>        Concerning your second question, I know that the DeFT code 
>originated the DeMon code (or viceversa; it is not very well stated) 
>which is handled at Montpellier (France) and Montreal by Salahub and 
>coworkers (there is a web page at http://palladium.enscm.fr/ ).

The methodology is similar, and the confusion might arise from the fact
that I started and worked on deMon as a grad student up to the time it was
purchased by Biosym.  DeFT came afterwards, and is the result of work
done in San Francisco and Ottawa.  It has greatly reduced functionality
w.r.t. to deMon, and DeFT has been more or less just a vehicle for testing
out new algorithms and methodologies.  Hopefully, the new release will be
efficient enough to give the other existing DFT codes a serious run for their
money.

However, DeFT's current release is mainly for those who like to have the
freedom to tinker around with source code and test out new ideas, without
having to fork over big $$$ or sign 10 page contracts.  Just like in the
good old days.....

Alain St-Amant