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Molecular mode-coupling theory for supercooled liquids: application to water
L Fabbian1, A Latz, R Schilling
1Dipartimento di Fisica and Istituto Nazionale per la Fisica della Materia, Universitá di Roma La Sapienza, Piazalle Aldo Moro 2, I-00185 Roma, Italy.
Summary
Mode-coupling theory (MCT) now describes complex molecular liquids near the glass transition. This advanced MCT accurately predicts supercooled water dynamics, validating its use for diverse molecular systems.
Area of Science:
- Condensed matter physics
- Chemical physics
- Computational chemistry
Background:
- Supercooled molecular liquids exhibit slow dynamics near the glass transition.
- Mode-coupling theory (MCT) has been successful for simple atomic and linear molecular liquids.
- Generalizing MCT to arbitrarily shaped molecules is crucial for understanding complex liquid dynamics.
Purpose of the Study:
- To generalize mode-coupling theory (MCT) for arbitrarily shaped, rigid molecules.
- To test the generalized MCT against molecular dynamics simulations of supercooled water.
- To validate MCT's applicability to network-forming molecular liquids.
Main Methods:
- Developed generalized mode-coupling equations for molecular systems.
- Numerically solved molecular MCT equations using two approximation schemes.
- Performed molecular dynamics simulations of supercooled water for comparison.
Main Results:
- Calculated the q-vector dependence of molecular nonergodicity parameters.
- Compared theoretical predictions with simulation data for supercooled water.
- Observed strong agreement between MCT predictions and simulation results.
Conclusions:
- The generalized MCT successfully describes the slow dynamics of supercooled molecular liquids.
- MCT is effective even for network-forming liquids like water.
- The study validates MCT as a powerful tool for complex liquid dynamics.