Abstract
Atomic structure is perhaps the information most critical to the understanding of materials behaviour, hence the great importance of x-rays and neutrons as probes. Although scattering is sensitive to pair and higher-order correlations, in most applications only the pair correlation is recovered. However, pair correlation is inadequate for a complete description of homogeneous systems in thermodynamic equilibrium; all correlations are required. It is often assumed that the pair correlations extracted from scattering experiments either uniquely determine or greatly restrict higher-order correlations. Here we argue on the basis of simulations and classical density functional theory that when the Hamiltonian is of pair-potential form the pair correlations do uniquely determine all higher-order correlations. However, we also demonstrate by simulation and prove algebraically that for specific many-body Hamiltonians additional information beyond pair correlations is needed to determine higher-order correlations. The derivations are underpinned by the close connection between fluctuations, applied fields, and correlations and identify approaches that hold promise for extracting higher-order correlations.
Original language | English (US) |
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Article number | 013 |
Pages (from-to) | 11585-11594 |
Number of pages | 10 |
Journal | Journal of Physics Condensed Matter |
Volume | 18 |
Issue number | 50 |
DOIs | |
State | Published - Dec 20 2006 |
ASJC Scopus subject areas
- General Materials Science
- Condensed Matter Physics