Crystal Density COD
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Different materials have different densities. From crystals the
density can be derive from the data of the COD archive in several
ways. In some entries the experimentally measured crystal density
(find out in which data elements). On the other hand, the density of a
crystal can be calculated by dividing the sum of the masses of all
atoms by of the elementary cage volume. The volume itself is available
or found in the COD record, or calculated from the crystal lattice
parameters.

Questions:

- how is the crystal density distributed in the structures described
  by COD? What what are the typical, minimum, maximum values for this
  parameter? What kind distribution form? What statistical parameters
  are the best for him describe?

- Are there structures described in the COD archive with an atypically
  large or low density? What is the reason for this?

- How does the crystal density correlate with the chemical composition
  of the material?

- Are the experimental and calculated values of the density of the
  structure match? If not, why? What is the accuracy of both values?
  Are the differences among them statistically significant?

Program:

This study requires a program that reads to and from COD CIF files
derives both experimentally determined and calculated crystal density
values. An opportunity can be provided for inspection and also output
of the crystal unit cell volume, both calculated and provided in the
CIF file, chemical formula of the substance and its mol. weight.