Structure and Stability of the Al(OH)3 Polymorphs Doyleite and Nordstrandite: A QuantumMechanical ab Initio Study with the CRYSTAL06 Code
Access Status
Authors
Date
2009Type
Metadata
Show full item recordCitation
Source Title
Additional URLs
ISSN
Collection
Abstract
The crystal structures and relative energies of doyleite and nordstrandite, two of the four aluminum trihydroxide polymorphs, were investigated at the periodic ab initio quantum-mechanical level with the CRYSTAL06 computer program, by using an all-electron Gaussian-type basis set and the hybrid B3LYP Hamiltonian. By least-energy optimizations of different starting arrangements of H atoms, a noncentrosymmetrical P1 structure model was proved to be slightly more stable than a P1 j one in doyleite. The primitive P1 j unit cell of nordstrandite was confirmed to contain four formula units, unlike doyleite (Z ) 2). The layered structures of nordstrandite and doyleite were shown to be closely related to that of bayerite, differing from one another by the interlayer shift vectors only. From the optimized positions of H atoms, the hydrogen bonding schemes and geometries were fully determined for both polymorphs. The computed Gibbs free energies at 298 K of bayerite, doyleite, and nordstrandite, referred to that of gibbsite, are 3.9, 4.4, and 15.2 kJ mol-1 per formula unit, respectively. Nordstrandite was then predicted to be largely the less stable of all four Al(OH)3 polymorphs
Related items
Showing items related by title, author, creator and subject.
-
Puschendorf, Mareike (2003)The Major Histocompatibility Complex (MHC) is a gene-dense region located on the short arm of chromosome 6 (6p21.31). This region contains the highly polymorphic HLA genes as well as many other genes with immunological ...
-
Chai, W.; Hong, M.; Song, L.; Jia, Guohua; Shi, H.; Guo, J.; Shu, K.; Guo, B.; Zhang, Y.; You, W.; Chen, X. (2015)Three luminescent polymorphs based on a new copper(I) complex Cu(2-QBO)(PPh3)PF6 (1, PPh3 = triphenylphosphine, 2-QBO = 2-(2'-quinolyl)benzoxazole) have been synthesized and characterized by FT-IR, UV-vis, elemental ...
-
Zykova-Timan, T.; Raiteri, Paolo; Parrinello, M. (2008)The polymorphism of an industrial important pigment (PR179) was studied with a combination of standard crystal structure prediction and metadynamics. The former provided a starting set of candidate polymorphs whose ...