Journal of

GEOsciences

  (Formerly Journal of the Czech Geological Society)

Original Paper

Sergey V. Krivovichev

Hydrogen bonding and structural complexity of the Cu3(AsO4)(OH)3 polymorphs (clinoclase, gilmarite): a theoretical study

Journal of Geosciences, volume 62 (2017), issue 2, 79 - 85

DOI: http://dx.doi.org/10.3190/jgeosci.231



Density functional theory (DFT) is used to determine positions of H atoms and to investigate hydrogen bonding in the crystal structures of two polymorphs of Cu3(AsO4)(OH)3: clinoclase and gilmarite. Hydrogen bonds in clinoclase involve interactions between hydroxyl groups and O atoms of arsenate tetrahedra, whereas the crystal structure of gilmarite features OHOH bonding, which is rather uncommon in copper hydroxy-oxysalts. Information-based parameters of structural complexity for clinoclase and gilmarite show that the former is more complex (IG,total = 213.212 bits/cell) than the latter (IG,total = 53.303 bits/cell), which indirectly points out that gilmarite is metastable. This suggestion is supported by the lower density of gilmarite (4.264 g/cm3) compared to that of clinoclase (4.397 g/cm3). The hypothesis of metastable character of gilmarite is in agreement with the Goldsmith’s simplexity principle and the Ostwald-Volmer rule.

Journal of Geosciences, Published by © Czech Geological Society, with support from the Czech Geological Survey.
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ISSN: 1802-6222

E-ISSN: 1803-1943