Subject: Re: CCL:Quantum CAChe?

From: "Victor Anisimov" <[email-masked]>
Date: Thu, 4 May 2000 11:28:01 +0200

Hi,

That's may be not so useless idea to talk about strength and weakness of
particular commercial software on CCL, I think. It will also give good
feedback for developers of these programs.

-----Original Message-----
From: Yeoh Hak Koon <[email-masked]>
Subject: CCL:Quantum CAChe?

:Could somebody who has experience using this software share some views
:on its suitability in the following?
:
:(a) Goodness in UV-Vis spectra simulation : overall shape and lambda max
:for transition metal complexes.  My main interest is in 3rd. row
:transition elements.

CAChe uses ZINDO for UV-Vis spectra calculations. It is general
spectroscopical semiempirical engine. Results of better quality for transition
metals can be obtained by MOPAC2000, but it supports only Fe, Pt, Cu, Ag, Mo
elements. If compounds of these elements are subject of semiempirical
research then one may need to consider MOPAC2000 as a solution because
quality of these parameters are really good.

:(b) Solvation models, mainly of water.  How well it incorporates its
:effects on orbital energies, and UV-Vis spectra?

As far as I know ZINDO does not support solvent effects. Please correct me
if I am wrong. Solvent simulations for UV-Vis spectra can be done by
MOPAC2000. Transition metals are not supported yet for this kind of
calculations but gas phase UV spectra can be calculated.

:(c) Any other points that you wish to highlight for consideration...like
:recommending another software!

If one needs better precision than semiempirical methods can provide then
DFT methods can be considered first as a cost effective solution. CAChe
includes DGauss module that can do this work.

CAChe does not include ab initio module but it may not be extremely
necessary. Keeping in mind that CAChe has been designed for synthetic
chemists who work with practical size molecules (but not model ones) and
need easy to use and fast computational tools then set of molecular
mechanics and semiempirical methods together with DFT engine provides
robust solution for most of computational chemistry problems.

This is a choice that we do as researches, either we solve theoretical
chemistry problem then one may need such tools like Jaguar Titan, for
example, or we solve a problem of a chemical experiment for what CAChe
has been designed I think perfectly.

With best regards,

Victor.

=========================================================================
Victor Anisimov, PhD, Software Researcher - Computational Chemistry
FQS Poland, Palac Pugetow, ul. Starowislna 13-15, 31-038 Krakow, Poland
Email: [email-masked]  Tel.(+48 12) 429 4345  Fax(+48 12) 429 6124
=========================================================================

---

From: David Gallagher <[email-masked]>
Date: Thu, 04 May 2000 15:24:58 -0700

Regarding ZINDO in CAChe, it includes the SCRF solvation model, and CAChe 
MOPAC includes the COSMO solvation model.

Regards

David Gallagher,
Fujitsu Systems Business of America, Inc.

At 11:28 AM 5/4/00 +0200, Victor Anisimov wrote:
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