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Modeling steps and kinks on the surface of calcite
Rune Kristensen1, S L S Stipp, Keith Refson
1Geological Institute, University of Copenhagen, Oster Voldgade 10, Copenhagen K, Denmark. runek@fys.ku.dk
The Journal of Chemical Physics
|October 30, 2004
Summary
This study models calcite cleavage, revealing obtuse steps dominate surfaces and kink energies are similar across geometries. These findings aid understanding of crystal surface formation and properties.
Area of Science:
- Surface science
- Materials science
- Crystallography
Background:
- Calcite (calcium carbonate) is a common mineral with a well-defined cleavage plane.
- Understanding surface reconstruction and defect energetics is crucial for predicting material behavior.
Purpose of the Study:
- To model the cleavage face of calcite, including steps and kinks.
- To investigate surface reconstruction and defect formation energies using computational methods.
Main Methods:
- Static lattice energy minimization.
- Interatomic potentials fitted to bulk calcite properties.
- Modeling of perfect surfaces, steps, and kinks.
Main Results:
- Calculated cleavage energy of 0.59 J m(-2) for calcite.
- Observed surface reconstruction to a (2 x 1) supercell in the presence of steps.
- Determined obtuse steps are energetically favored over acute steps.
- Found similar formation energies for various kink geometries.
Conclusions:
- Surface reconstruction on calcite is influenced by cleavage steps, potentially explaining experimental observations.
- Obtuse steps are more prevalent on cleaved calcite surfaces.
- Energetics do not strongly differentiate between kink site frequencies on calcite surfaces.