This database provides structural data of 20 proteinogenic amino acid and their amino-methylated and acetulated (capped) dipeptides and their complex with divalent cations: Ca2+, Ba2+, Sr2+, Cd2+, Pb2+, and Hg2+.
Detailed describtion of database and how it was created can be found from article
"First-principles data set of 45,892 isolated and cation-coordinated conformers of 20 proteinogenic amino acids" by Matti Ropo, Markus Schneider, Carsten Baldauf, and Volker Blum.
Scientific Data 3, 160009 (2016) (open access), preprint.
The database is updated (May 2017) to new version of the dataset. Currently NOMAD contain the old version of the dataset.
Alternative method to accedd data is a NoMaD repository