MOLPRO

14 INTEGRATION 84
14.1 Sorted integrals
If the integrals are stored on disk, immediately after evaluation they are sorted into complete
symmetry-packed matrices, so that later program modules that use them can do so as efficiently
as possible. As discussed above, it is normally not necessary to call the integral and sorting
programs explicitly, but sometimes additional options are desired, and can be specified using
the INT command, which should appear after geometry and basis specifications, and before any
commands to evaluate an energy.
INT, [[NO]SORT,] [SPRI=value]
SORT, [SPRI=value]
INT,NOSORT;SORT can be used to explicitly separate the integral evaluation and sorting
steps, for example to collect separate timing data. With value set to more than 1 in the SPRI
option, all the two-electron integrals are printed.
The detailed options for the integral sort can be specified using the AOINT parameter set, using
the input form
AOINT, key1=value1, key2=value2, ...
AOINT can be used with or without an explicit INT command.
The following summarizes the possible keys, together with their meaning, and default values.
c final
c sort1
c seward
compress
thresh
io
Integer specifying the compression algorithm to be used for the
final sorted integrals. Possible values are 0 (no compression), 1
(compression using 1, 2, 4 or 8-byte values), 2 (2, 4 or 8 bytes),
4 (4, 8 bytes) and 8. Default: 0
Integer specifying the compression algorithm for the intermediate
file during the sort. Default: 0
Integer specifying the format of label tagging and compression
written by the integral program and read by the sort program.
Default: 0
Overall compression; c final, c seward and c sort1 are forced
internally to be not less than this parameter. Default: 1
Real giving the truncation threshold for compression. Default:
0.0, which means use the integral evaluation threshold (GTHRESH,TWOINT)
String specifying how the sorted integrals are written. Possible
values are molpro (standard MOLPRO record on file 1)
and eaf (Exclusive-access file). eaf is permissible only if the
program has been configured for MPP usage, and at present
molpro is implemented only for serial execution. molpro is
required if the integrals are to be used in a restart job. For maximum
efficiency on a parallel machine, eaf should be used,
since in that case the integrals are distributed on separate processorlocal
files.
For backward-compatibility purposes, two convenience commands are also defined: COMPRESS
is equivalent to AOINT,COMPRESS=1, and UNCOMPRESS is equivalent to AOINT,COMPRESS=0.