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Phase diagram of silica from computer simulation.
Ivan Saika-Voivod1, Francesco Sciortino, Tor Grande
1Dipartimento di Fisica and Istituto Nazionale per la Fisica della Materia, Università di Roma La Sapienza, Piazzale Aldo Moro 2, I-00185, Roma, Italy.
Physical Review. E, Statistical, Nonlinear, and Soft Matter Physics
|February 9, 2005
Summary
This study evaluates the BKS potential for silica using molecular dynamics simulations. While quantitative phase boundaries differ from real silica, the model qualitatively reproduces the phase diagram topology.
Area of Science:
- Materials Science
- Computational Chemistry
- Condensed Matter Physics
Background:
- The BKS potential is a widely used model for silica in molecular dynamics (MD) simulations.
- Accurate simulation of silica's phase diagram is crucial for understanding its behavior under various conditions.
Purpose of the Study:
- To evaluate the accuracy of the BKS potential in reproducing the phase diagram of silica.
- To compare simulated phase boundaries with experimental data and identify discrepancies.
- To assess the qualitative and quantitative agreement of the BKS model with real silica behavior.
Main Methods:
- Conducting molecular dynamics (MD) simulations for liquid silica and three crystalline phases (beta-quartz, coesite, stishovite).
- Calculating the total Gibbs free energy for each phase across a wide range of temperatures and densities.
- Determining phase boundaries by identifying the intersection of free energy surfaces.
Main Results:
- Quantitative discrepancies were found between the BKS potential's phase boundaries and those of real silica.
- The topological features of the real silica phase diagram were successfully reproduced by the BKS model.
- Comparison with previous studies revealed correlations between phase boundaries and liquid-state thermodynamic anomalies.
Conclusions:
- The BKS potential offers a satisfactory qualitative description of a silica-like material.
- Despite quantitative inaccuracies, the model's ability to reproduce phase diagram topology is valuable for simulations.
- Further refinement of the BKS potential may be needed for precise quantitative predictions.