Diffusional Anomaly and network dynamics in liquid silica

Abstract

The present study applies the power spectral analysis technique to understand the diffusional anomaly in liquid silica, modeled using the BKS potential. Molecular dynamics simulations have been carried out to show that power spectrum of tagged particle potential energy of silica shows a regime with 1/f dependence on frequency f which is the characteristic signature of multiple time-scale behaviour in networks. As demonstrated earlier in the case of water (J. Chem. Phys., 122, 104507 (2005)), the variations in the mobility associated with the diffusional anomaly are mirrored in the scaling exponent alpha associated with this multiple time-scale behaviour. Our results indicate that in the anomalous regime, as the local tetrahedral order decreases with temperature or pressure, the coupling of local modes to network reorganisations increases and so does the diffusivity. This symmetry-dependence of the vibrational couplings is responsible for the connection between the structural and diffusional anomalies.

30 pages, 9 figures

References in corpus (12)

• Fragile-to-strong transition and polyamorphism in the energy landscape of liquid silica
• Molecular structural order and anomalies in liquid silica
• Computer simulations of liquid silica: equation of state and liquid-liquid phase transition
• Structural Order for One-Scale and Two-Scale Potentials
• Quantification of Order in the Lennard-Jones System
• 1/f noise: a pedagogical review
• Cooperative Origin of Low-Density Domains in Liquid Water
• Phase diagram of silica from computer simulation
• Configuration space connectivity across the fragile to strong transition in silica
• Effect of the Berendsen thermostat on dynamical properties of water
• Spectral Signatures of the Diffusional Anomaly in Water
• Model-based fit procedure for power-law-like spectra

Cited by in corpus (7)

• Excess entropy, Diffusivity and Structural Order in liquids with water-like anomalies
• Water-like hierarchy of anomalies in a continuous spherical shouldered potential
• Molecular dynamics computer simulation of amorphous silica under high pressure
• Fragile-to-strong transition in liquid silica
• 1/f spectrum and memory function analysis of solvation dynamics in a room-temperature ionic liquid
• Multiple Time-Scale Behaviour and Network Dynamics in Liquid Methanol
• The Widom line and noise power spectral analysis of a supercritical fluid