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Topological analysis of the electron density of the clinopyroxene structure by the maximum entropy method; an exploratory study

Marcello Merli and Fernando Camara
Topological analysis of the electron density of the clinopyroxene structure by the maximum entropy method; an exploratory study
European Journal of Mineralogy (October 2003) 15 (5): 903-911

Abstract

In the framework of a series of methodological studies to test the reliability of reconstruction of the electron density distribution (EDD) by the maximum entropy method (MEM), we have attempted to check the possibilities of getting further information about the structural changes as a function of the chemical composition occurring in low-Ca clinopyroxenes by the analysis of the topology of the MEM EDD. The results of this study show that the topological analysis of MEM EDD yields results comparable to the bond critical points characteristics obtained in ground state EDD in minerals. Notable differences related to solid solutions have been found only at the M2 site of clinopyroxene structure. An attempt to describe the bond character at this site in the presence of significant solid solutions has shown differences related to chemical substitution that can be described in terms of variable ionicity. This result could be ultimately related to the different thermodynamic behaviour of the P2 (sub 1) /c<-->C2/c phase transitions shown by chemically different clinopyroxenes. Since MEM can deal with experimental data on solid solutions, which cannot be treated with other available methods to reconstruct the experimental electron density, this approach opens new possibilities for the study of changes in the EDD topology of minerals with complex chemical substitutions.


ISSN: 0935-1221
EISSN: 1617-4011
Serial Title: European Journal of Mineralogy
Serial Volume: 15
Serial Issue: 5
Title: Topological analysis of the electron density of the clinopyroxene structure by the maximum entropy method; an exploratory study
Affiliation: Universita di Pavia, Dipartimento di Scienze della Terra, Pavia, Italy
Pages: 903-911
Published: 200310
Text Language: English
Publisher: Schweizerbart'sche Verlagsbuchhandlung (Naegele u. Obermiller), Stuttgart, Federal Republic of Germany
References: 37
Accession Number: 2004-020045
Categories: Mineralogy of silicates
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 5 tables
Secondary Affiliation: CNR-Instituto di Geoscienze e Georisorse, ITA, Italy
Country of Publication: Germany
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute.
Update Code: 200406
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