Introduction to surface chemistry:
http://www.chem.qmul.ac.uk/surfaces/scc/

ASE documentation:
https://wiki.fysik.dtu.dk/ase/

Downloading unit cell coordinates:
https://www.materialsproject.org/

VASP documentation and some workshop slides:
https://www.vasp.at/
https://www.vasp.at/vasp-workshop/slides/

DFT book by Prof. John Kitchin:
http://kitchingroup.cheme.cmu.edu/dft-book/