CCL:UV spectrum calculation (new question)

Hi,
 I'm curious how well INDO/S-RPA works against INDO/S-CIS for large systems.
 I only remember one article by M. Zerner quite a long time ago..
 Probably the calculation takes a lot longer (Hamiltonian matrix is four times
 as big since mixing of particle-hole and hole-particle excitations occurs).
 About the excitation energies: If I'm not mistaken both CIS and RPA are
 consistent methods in electron correlation up to 1st order in one-particle
 excitation energies, but only RPA is up to 1st order for transition dipole
 moments). Two-particle excitations are not accounted for in CIS, and only
 partially in RPA, am I right ?
 Are there any problems with numerical instabilities with the implemented RPA
 scheme in a INDO/S-RPA calculation ?
 Serge
 > > -----Original Message-----
 > > From: Mark Thompson [mailto:mark{at}planaria-software.com]
 > > Sent: Tuesday, May 27, 2003 1:47 PM
 > > To: Jesus Rodriguez-Otero; chemistry{at}ccl.net
 > > Subject: CCL: UV spectrum calculation
 >
 >
 >
 > Dear Jesus,
 >
 > ZINDO does indeed give good results for large organic systems, mainly those
 > with low-energy pi-pi* excitations.  As with many semi-empirical methods,
 > it
 > works best on a series of related molecules where you might be interested
 > in
 > the effects of certain substitutents.  Also, the effects of solvent can be
 > very important and several solvent models have been applied to the ZINDO
 > method with good results.
 >
 > Here are a couple of my publications where I applied ZINDO to studies of
 > photosynthetic pigments:
 >
 >  "Excited States of the Bacteriochlorophyll b Dimer
 >  of Rhodopseudomonas viridis: A QM/MM Study of the
 >  Photosynthetic Reaction Center That Includes MM
 >  Polarization" J. Phys. Chem. 1995, 99, 6374-6386.
 >  Mark Thompson and Gregory Schenter
 >
 >  "Effect of a Polarizable Medium on the Charge-Transfer
 >  States of the Photosynthetic Reaction Center from
 >  Rhodopseudomonas viridis. " I. Am. Chem. Soc.
 >  1990, 112, 7828.  Mark Thompson and Michael Zerner
 >
 >
 > ZINDO is available in the ArgusLab 3.1 program.  In addition to the normal
 > ZINDO method (based on singles-CI description of the excited state),
 > ArgusLab also implements the ZINDO-RPA method which includes contributions
 > > from certain low-lying doubles and is particularly good at describing
 > rotational spectra and giving good agreement between dipole length and
 > dipole velocity transition moments.  ArgusLab also implements the
 > Self-Consistent Reaction Field model of Zerner and Karlsson.
 >
 > You can obtain ArgusLab at http:://www.arguslab.com
 >
 >  Mark Thompson
 >
 > =================================
 >  Mark Thompson, Ph.D.
 >  Planaria Software
 >  PO Box 55207
 >  Seattle, WA  98155
 >
 >  http://www.arguslab.com
 >  FAX: 206-440-3305
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