Title: Representational analysis of extended disorder in atomistic ensembles derived from total scattering data

Abstract

With the increased availability of high-intensity time-of-flight neutron and synchrotron X-ray scattering sources that can access wide ranges of momentum transfer, the pair distribution function method has become a standard analysis technique for studying disorder of local coordination spheres and at intermediate atomic separations. In some cases, rational modeling of the total scattering data (Bragg and diffuse) becomes intractable with least-squares approaches, necessitating reverse Monte Carlo simulations using large atomistic ensembles. However, the extraction of meaningful information from the resulting atomistic ensembles is challenging, especially at intermediate length scales. Representational analysis is used here to describe the displacements of atoms in reverse Monte Carlo ensembles from an ideal crystallographic structure in an approach analogous to tight-binding methods. Rewriting the displacements in terms of a local basis that is descriptive of the ideal crystallographic symmetry provides a robust approach to characterizing medium-range order (and disorder) and symmetry breaking in complex and disordered crystalline materials. Lastly, this method enables the extraction of statistically relevant displacement modes (orientation, amplitude and distribution) of the crystalline disorder and provides directly meaningful information in a locally symmetry-adapted basis set that is most descriptive of the crystal chemistry and physics.

Authors:

Neilson, James R. ^[1]; McQueen, Tyrel M. ^[2]

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+ Show Author Affiliations

1. Colorado State Univ., Fort Collins, CO (United States). Dept. of Chemistry
2. Johns Hopkins Univ., Baltimore, MD (United States). Dept. of Chemistry, Materials Science and Engineering, and Physics and Astronomy

Publication Date:

Sun Sep 20 00:00:00 EDT 2015

Research Org.:

Johns Hopkins Univ., Baltimore, MD (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Basic Energy Sciences (BES)

OSTI Identifier:

1344885

Grant/Contract Number:  

FG02-08ER46544; AC52-06NA25396

Resource Type:

Accepted Manuscript

Journal Name:

Journal of Applied Crystallography (Online)

Additional Journal Information:

Journal Name: Journal of Applied Crystallography (Online); Journal Volume: 48; Journal Issue: 5; Journal ID: ISSN 1600-5767

Publisher:

International Union of Crystallography

Country of Publication:

United States

Language:

English

Subject:

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; extended disorder; atomistic ensembles; modeling; pair distribution function analysis