16GB file problem in Gaussian
- From: Alessandro Ponti
<alessandro.ponti-.at.-istm.cnr.it>
- Organization: CNR - CSRSRC
- Subject: 16GB file problem in Gaussian
- Date: Fri, 27 Jun 2003 14:25:38 +0200
Dear All,
recently I met with the problem that the maximum total RWF file length
in
Gaussian98 is 16GB. (NB: I'm not referring to the maxiumum file length
allowed
by your OS; such problem is solved by splitting the RWF into several
small
files). I met the 16GB problem while trying MP2 frequency, MP4 energy,
and QCISD
energy calculations. Apparently, Gaussian98 cannot deal with more than
16GB disk
space, eg when you set MaxDisk=17GB. Looking at the route section,
IOp(8/27)
("maximum amount of dik to use" in the four-index
transformation) is negative
and equal to -1GB (recall that IOp(8/27) is expressed in Words). Here's
a small
table of my experiments
MaxDisk : 1 2 ... 15 16 17 ... 31 32 33 ...
IOp(8/27) : 1 2 ... 15 -16 -15 ... -1 0 1 ...
Perusing G98 manuals and source files was useless. After searching in
the net,
it seems that the 16GB problem is related to Gaussian98 addressing by
32-bit
integers. At
http://www.ccl.net/ASC/PET/CCM/skeleton/software/gaussian/gaussian-tips.html
I found a brief text claiming this problem can be circumvented, at least
partially:
"The second limit has a less satisfactory workaround. Scratch
data stored in the
read-write file can be diverted into a separate file with the option
%usescr
while this does not evenly balance the usage it does allow
specification of 32
GB of storage and depending on the type of calculation more or less
complete
utilization of this whole amount."
However I did not really understand what it means.
Does anyone knows how to overcome the 16GB limit? Has anyone
information about
this problem? Any little piece of information might be a precious clue
to us.
I thank you all in advance for any help.
Bye
Alessandro
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