Subject: RYSROT problem summary

From: [email-masked] (Greg Koyanagi)
Date: Thu, 27 Jan 94 13:38:07 EST

Dear netters,

Thanks to all who replied to my problem.  

However this was, unfortunately not a case of more is better.
Pg 93 of the g92 manual states that 2,000,000 words is sufficient for 
up to 110 basis functions and 16 atoms.  The limit of 2,800,000 was
the most a user on our system is (on average) supposed to take when the
system is loaded with jobs (as it usually is).

The word from Gaussian is:
===========================================================
  Dr. Koyanagi,

   The Rys algorithm is a quadrature method and requires the roots to a
one dimensional polynomial on the region (0.0,1.0).  This error occurs
when the root finding code fails to find appropriate roots.  It is
quite un-common and is a perverse combination or coefficients which are
responsible.

   I am re-running your case to make sure I understand where it is failing.
With Gaussian 92 I am not sure there is much we can do but I will see a
minor
tweak is helpful.

Doug Fox
[email-masked]

  Greg,

   I have run the test case you sent, using the geometry in the OPT input
and run an MP2 FREQ on my HP system here without problem.  This may be
an SGI specific problem.  I will send a copy of this to SGI for
confirmation.

Doug Fox
[email-masked]

=======================================================
Which doesn't suprise me because we've been experiencing
O/S problems for the last 5-6 weeks.  Which I may as well ask
about that as well:

Has anyone (on an R3000 SGI, O/S 4.0.5) experienced problems where the
O/S after a time, does not release memory back to the user programs?
After about ten days of operation the System Activity Reporter will
show a steady drop of FREE MEMORY until there is about slightly less
than 2Megs and then swapping takes over in a big way.

I ask this here in this forum because ~95% of the CPU time on our
system goes to ab initio computations.

Greg Koyanagi                      [email-masked]
Department of Chemistry            519-885-1211x6388
Universtiy of Waterloo
Waterloo, Ontario, CANADA
N2L 3G1