Benchmark Info. Available



 Recently, in regard to the availability of Gaussian on high-end PC's, someone
 mentioned that it would be helpful to have comparative information available on
 the relative performance on other machines.  Here in the MSRC we have just
 completed a benchmark study of Gaussian 90 and 92, as well as many other
 popular ab initio packages (GAMESS-US, GAMESS-UK, HONDO, DISCO, MOLPRO
 and ACES II).  We examined their respective performance in terms of CPU time
 and wall clock time on a variety of machines, including workstations from Sun,
 HP, IBM and SGI, as well as large machines like a Cray Y-MP and a C90.
 In an attempt to avoid skewing the results towards one particular type of
 calculation, we included 5 different molecules (ranging from small, with high
 symmetry to large with little or no symmetry).  Among the methods examined
 were RHF (conventional and direct), UHF, MP2 (conventional and direct), MP4,
 gradients and hessians for RHF and MP2, CISD, CCSD, QCISD and CASSCF.
 A small amount of information was included on the recently introduced DEC Alpha
 workstations.  Lastly, there is a reference to several density functional
 programs which we have also benchmarked, using some of the same molecules and
 similar quality Gaussian basis sets.
 This information is contained in a Pacific Northwest Labs technical report
 which is slowly winding its way through clearance.  We will make it available
 to anyone requesting it and a PostScript version will be available for
 downloading via anonymous FTP.  The latter has not yet been set up.
 People will have to judge the cost effectiveness of workstations vs super-
 computers vs PCs for themselves.  However, I can't help but note that the
 quantity which is of primary interest to most scientists using these programs
 is the "time-to-solution".  Very fast, very expensive computers are
 nearly
 always oversubscribed.  This results in lengthy waits in long queues for a
 chance at the limited resources.  Our experience has been that it is often
 possible for the unemcumbered tortoise to beat the overburdened hare.
 David Feller
 Molecular Science Research Center
 d3e102;at;pnlg.pnl.gov