As computational chemistry methods enjoy unprecedented growth,
computer power increases and price/performance ratio drops, a large
number of crystal structures can today be refined and their properties
computed using modern theoretical approaches, such as DFT, HF, QM/MM,
MCMM methods. Availability of several open source codes for
computational and quantum chemistry and open-access crystallographic
databases enables large scale computations of material structures and
properties. We thus increasingly feel that an open collection of
theoretically computed chemical structures would be a valuable
resource for chemists, physicists, engineers and crystallographers. To
address this need, we have launched a Theoretical Crystallography Open
Database (TCOD, http://www.crystallography.net/). The TCOD database
sets a goal to collect a comprehensive set of computed chemical and
crystal structures that would be made available under Open Data
license and invites all computational to deposit their published
computation results or pre-publication data. Accompanied with a large
set of experimentally determined structures in the COD database, the
TCOD opens immediate possibilities for experimental and theoretical
data cross-validation, matching chemical structure with computed
chemical properties, and linking to numerous other chemical,
biological and medical databases.

To ensure high quality of deposited data, TCOD offers ontologies in a
form of CIF dictionaries that describe parameters of computed chemical
and crystal structures, and an automated pipeline that checks each
submitted structure against a set of community-specified criteria for
convergence, computation quality and reproducibility. The scope of
TCOD and validation tools make TCOD a high-quality, comprehensive
theoretical structure database, immediately usable in a broad range of
disciplines.