[molpro-user] disk space in CCSD(T) and integral thresholds

[Fabio Mariotti]

	Dear Molpro users,

	I need to know if there is any little trick
	I can use to reduce just a bit the disk space.

	I can use a nice cluster with queues of max 8h
	and local scratch disk of about 80Gb (on the same
	Linux OS physical disk)
	and I have a CCSD(T) calculation which takes
	8h30min (quite long time spent in I/O)
	and ~85Gb of scratch. (and cannot use symmetry:( )

	So the questions:
	1) Default compression algorithm is aoint,compress=1.
	is there any different option to improve compression?

	2) the code writes first files with names of the type:
	eaf_T2100004985.TMPx001
	which if I understood correctly are the main
	integral files, then files of the type
	eaf_T2400004985.TMPx001
	which should be the sort files.
	after the sort, it starts to create files with names of the type:
	eaf_T3100004985.TMPx001
	which seem to be a copy of the integral files.
	I removed the files eaf_T2100004985.TMPx001 by hand
	while the program was generating the eaf_T3100004985.TMPx001 files.
	and the calculation ended without any problem and using about 20Gb
	less of disk space.
	Can I avoid this extra copy of integrals?

	3) Which one is the correct option to set the integral threshold?
	I have an input with both:
	gthresh,oneint=1.0D-11,twoint=1.0D-11;gthresh,zero=1.0D-12,prefac=1.0D-11
	and
	aoint,compress=1,thresh=1.0D-10,io=eaf;
	but on output I get:
 Contracted 2-electron integrals neglected if value below      1.0D-12
 AO integral compression algorithm  1   Integral accuracy      1.0D-12

	Am I misunderstanding or I have a problem with my compiled version?


	thanks in advance
	Fabio



-- 
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Dr. F.Mariotti - mariotti at ir.phys.chem.ethz.ch
ETH Zurich - Honggerberg, Zurich, Switzerland
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