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A simple method for the prediction of the orientation of H 2 O molecules in ionic crystals
Author(s) -
Ghazisaeed Seyedayat,
Majzlan Juraj,
Plášil Jakub,
Kiefer Boris
Publication year - 2018
Publication title -
journal of applied crystallography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.429
H-Index - 162
ISSN - 1600-5767
DOI - 10.1107/s1600576718008567
Subject(s) - orientation (vector space) , degenerate energy levels , molecule , density functional theory , chemistry , neutron diffraction , simple (philosophy) , crystallization , ab initio quantum chemistry methods , displacement (psychology) , molecular physics , ab initio , tetrahedron , crystallography , ionic bonding , computational chemistry , thermodynamics , physics , crystal structure , ion , geometry , mathematics , quantum mechanics , psychology , philosophy , organic chemistry , epistemology , psychotherapist
A robust and fast method is presented that provides a simple real‐space convergent solution for identifying equilibrium orientations of crystallization H 2 O molecules in ionic crystals, on the basis of zero net torque. The predicted H 2 O orientations constrained by rotational equilibrium are compared with neutron scattering experiments and/or ab initio density functional theory (DFT) calculations. The comparison shows that predicted and observed H 2 O orientations are consistent, demonstrating the reliability of the reported torque method. Moreover, the rotational equilibrium conditions predict an alternative, not previously observed, H 2 O orientation in kernite [Na 2 B 4 O 6 (OH) 2 ·3H 2 O], and this may explain anomalously large displacement parameters that have been reported for this mineral. Complementary DFT computations corroborate that the two orientations are geometrically distinct and energetically near degenerate.