Memory allocation for Molpro

H. -J. Werner werner at
Mon Feb 18 14:58:26 GMT 2002

Dear Molpro users,

some people have complained that they can allocate only less
memory with molpro2002 than with molpro 2000. This is due
to the increased size of the molpro executable. In
particular, the defaults for the maximum number of valence 
orbitals and basis functions are now higher, and 
probably larger than needed by most people. You can 
reduce this when running configure, but note that the
program must be recompiled entirely when the dimensions
are changed. This might help a little, but not very much.
There appears to be a problem with the linux operating
system, which does not allow to allocate more than 
about 1 GB in total (including the program size itself),
even if the machine has more memory. We are trying to
find out how to avoid this problem.

Also, we found that there is a problem with recent linux 
kernels (latest tested is 2.4.17). With kernels later than 
2.4.9 our machines frequently hang if too much memory is 
used, or if 2 jobs with large memory requirements are started 
simultaneously.  The same happens with big parallel jobs. 
Indicative of this problem is that one can neither kill the 
jobs nor reboot the machine. So far, we have not seen this 
problem with kernel 2.4.9, and we therefore recommend this
version for the time being.

Joachim Werner

Prof. Hans-Joachim Werner
Institute for Theoretical Chemistry
University of Stuttgart
Pfaffenwaldring 55
D-70569 Stuttgart, Germany
Tel.: (0049) 711 / 685 4400
Fax.: (0049) 711 / 685 4442
e-mail: werner at

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