[molpro-user] direct-MC-SCF is filling harddisk

Gerald Knizia knizia at theochem.uni-stuttgart.de
Wed Jun 16 07:19:31 BST 2010

On Tuesday 15 June 2010 12:41, andreas.b.fuchs at basf.com wrote:
> Okay, lsof showed me some big files with the status 'deleted'. I assume
> that these are some temporary files which are responsible for the filling
> of my disk.
> Has anyone an idea what is written to these files and how I can prevent
> molpro from writing to these files?

There are some very small items which, as far as I know, are always written to 
disk (like orbital matrices, one-electron operators). There are also some 
items like the K^ij_ab Exchange- and J^ij_ab Coulomb matrices that can get 
semi-large in certain cases, and which I think are also always written to 
disk when required, but I am not sure about that.
   A correlation method being "direct" mainly means that the full 4 index AO 
integrals are not written to disk; these are the quantities that easily take 
up TBs and typically are the main disk space bottleneck. The other 
quantities, like the K^ij_ab and J^ij_ab integrals, are usually smaller than 
these by at least two orders of magnitude (but if using very small basis 
sets, the relative size ratio can become worse).
   So, in short: "direct" does not mean that nothing is written to disk, only 
that much less is written to disk; and there are some special cases in which 
the written data is still not entirely negligible compared with the 
non-direct calculation.
Gerald Knizia

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