Dear TCODers!
sorry for a period of silence. It took me a while to digest all ideas expressed on this list, catch up with the work done by other groups (Quichote, CompChem).
I am toying with the idea that TCOD should have 3 levels of structure description:
-- level 0: - cell constants; - atomic coordinates; - literature reference.
Standard CIF dictionaries are enough for such description.
-- level 1: - same as in level 0, plus any parameters that permit qualified person to judge if the structure has converged and how good it is. The parameters should include residual force on atoms (2014-02-10 16:16, Björkman Torbjörn), energy change(s) in the last cycle(s), and references to basis set, pseudo-potentials, XC functionals, etc. (as described in our dictionaries and in http://www.xml-cml.org/dictionary/compchem/). Basis sets can be referenced as in https://bse.pnl.gov/bse/portal;
-- level 2: - same as in level 1, plus:
- copies of all input files (such as .inp files), or stable references to them (possible in case of widely used basis sets or pseudo-potentials); the text of these files could be stored, unparsed, in appropriate CIF data items so that one can extract those files and run the code automatically;
- command line used to run the code;
- optionally, output logs of the run;
- the name, URL reference, and version of the program used for computations;
- for F/LOSS programs and systems, we can store the source code and the packages -- these can be re-run on emulators when the code and the systems become obsolete.
Rationale for the level 0: at the moment, all TCOD CIFs are of this kind, so we are just expressing the state of the art. This assumes that referees and editors were careful enough to review the paper, check the convergence, that nobody has confused the coordinates, etc.
Rationale for the level 1: we need some criteria to select structures for further processing, review, etc. We will start with the minimal set of tags (data names), and add more when necessary.
Rationale for the level 2: in the nearest time, the computations can be re-run from such representation, and modified computations can be done. In the more distant future, the codes will become obsolete as Stefaan correctly predicts in his 2013-08-19 18:30 e-mail, but we can still read, analyse and parse the logs, and possibly extract more information that was parsed during the deposition.
Copying and dumping all inputs and outputs captures all relevant information, allows to re-parse it in the future if necessary and accommodates any new codes and new developments of old codes.
People who are not willing to share their scripts can stick to level 1 as long as their publishers, funders and community do not insist on level 2 :). TCOD as a database is neutral about this (although TCOD maintainers or participants can have their strong opinions on the subject ;)
Large intermediate or derivable files (electron/spin density maps, wave functions) will not be stored at the moment, and if they will, they will be added as separate files.
What you think about such policy?
Regards, Saulius
PS. In a while, I'll send you a version of our poster for IUCr for the review, and some updates to the COD dictionaries.