/usr/share/doc/libchemps2/html/_sources/ is in chemps2-doc 1.8.3-2.
This file is owned by root:root, with mode 0o755.
..
/usr/share/doc/libchemps2/html/_sources/caspt2.txt
/usr/share/doc/libchemps2/html/_sources/dmrgscf.txt
/usr/share/doc/libchemps2/html/_sources/dmrgscfcalcs.txt
/usr/share/doc/libchemps2/html/_sources/handson.txt
/usr/share/doc/libchemps2/html/_sources/index.txt
/usr/share/doc/libchemps2/html/_sources/inoutput.txt
/usr/share/doc/libchemps2/html/_sources/interfaces.txt
/usr/share/doc/libchemps2/html/_sources/matrixelements.txt
/usr/share/doc/libchemps2/html/_sources/method.txt
/usr/share/doc/libchemps2/html/_sources/publications.txt
/usr/share/doc/libchemps2/html/_sources/resources.txt
/usr/share/doc/libchemps2/html/_sources/sourcecode.txt
/usr/share/doc/libchemps2/html/_sources/symmetry.txt