Subject: Re : CCL messages about coupled-cluster optimizations in G94, other progs

From: "John D. Watts" <[email-masked]>
Date: Tue, 27 May 1997 14:27:54 -0400 (EDT)

Dear Pablo and other CCL subscribers,

   One of my colleagues brought these messages to my attention and asked me to
   send a note to you and the CCL. I apologize in advance to CCL subscribers
   who have already seen plenty of useful messages on this issue, but my
   colleague is persistent, so here goes ...
   
   anyway, the point i want to address is what the ACES II program from
   Professor R.J. Bartlett's group in the Quantum Theory Project of the Univer-
   sity of Florida can do as far as analytical CCSD and CCSD(T) derivatives
   (gradients) are concerned. a number of subscribers mentioned the capabil-
   ities of ACES II in this regard.
   
   ACES II can do analytical gradients for CCSD with RHF, UHF, ROHF, and
   certain classes of QRHF reference functions. it can also do CCSD gradients
   for a two-determinant reference for open-shell singlets based on QRHF
   orbitals. for CCSD(T) it can do analytical gradients for RHF, UHF, and
   ROHF references. it can also do QCISD and QCISD(T) gradients for RHF and
   UHF, although we prefer CCSD-based methods to the QCI truncations.
   
   analytical gradients are also available for the excited state CCSD method
   known as equation-of-motion CCSD (many call this linear response CCSD).
   
   please note that Qiang Cui's statement about analytical hessians does not
   apply to the version of ACES II distributed by the QTP; he has access to
   a private version of the code developed subsequent to their time at Florida
   by John Stanton and Juergen Gauss. my remarks refer to the code distributed
   by QTP.
   
   anyone who wants further information can send email to [email-masked]
   and/or visit our web page. the latter was given by Eric Patterson.
   
   i hope these remarks will be of some use. i am not a CCL subscriber, so if
   you want to follow up any of these points, please email me directly.
   
   John