Add COPYRIGHT file and/or clarify copyright years

[mbanck]

CP2K has a top-leve COPYRIGHT file that clearly states the years the CP2K Developers Group assert on the copyright.

The standard copyright boilerplate for the DBCSR source files does not mention a year, nor is it mentioned anywhere else. I think it would be prudent to clarify that, either by introducing a COPYRIGHT file, (probably contentious) by noting the years of individual involvements in AUTHORS or by adding a short "Copyright (c) 20XX-2020 The DBCSR Developers Group" line at the top of README.md.

Though I understand the code was (partially?) taken from CP2K and it might be difficult to come up with a lower bound for copyright?

Just looking at the code, a few files have a "History" section and 2010 seems to be the earliest year, so I am going with "2010-2020 DBCSR Developers Group" for now, would that be problematic?

[oschuett]

Most of the history comments were removed during the transition to FORD. I believe this is the first commit for DBCSR, which is from May 2009

Since CP2K now states the copyright in each sourcefile, the top-level COPYRIGHT file is redundant and we should remove it. This would also allow Github to properly recognize CP2K as GPL project.

[alazzaro]

@dev-zero did a great job to copy the entire history of the files commits we are using. Therefore the first set of commits is:

https://github.com/cp2k/dbcsr/commits/develop?after=1da47620ea8ee33d68c6753e4c6adb1053c7fa73+2799&branch=develop

Therefore, I would say that it is worth mentioning 2001 as the beginning of the project.

[oschuett]

I've opened cp2k/cp2k#1245 to discuss the fate of CP2K's COPYRIGHT file.

[dev-zero]

CP2K has a top-leve COPYRIGHT file that clearly states the years the CP2K Developers Group assert on the copyright.

The standard copyright boilerplate for the DBCSR source files does not mention a year, nor is it mentioned anywhere else. I think it would be prudent to clarify that, either by introducing a COPYRIGHT file, (probably contentious) by noting the years of individual involvements in AUTHORS or by adding a short "Copyright (c) 20XX-2020 The DBCSR Developers Group" line at the top of README.md.

Negative. After reading through some of the materials from the FSFE on licensing and the recommendations from GH I came to the conclusion that this is not needed and only adds noise to commits, like the bogus "increase copyright year" each year done by some projects (if needed the latest copyright date taken is the one from the last substantial commit to a file, hence updating the year does nothing at all).
Hence I trust the version control system more in tracking this metadata (especially with a distributed VCS) and if you want to improve it then we should start signing commits.

As for the start year I guess we could add it to the README.md for documentation purposes, and since parts of DBCSR was factored out from CP2K we have to assume the same start date as CP2K.