Local Properties of the Potential Energy Landscape of a Model Glass: Understanding the Low Temperature Anomalies

Abstract

Though the existence of two-level systems (TLS) is widely accepted to explain low temperature anomalies in the sound absorption, heat capacity, thermal conductivity and other quantities, an exact description of their microscopic nature is still lacking. We performed computer simulations for a binary Lennard-Jones system, using a newly developed algorithm to locate double-well potentials (DWP) and thus two-level systems on a systematic basis. We show that the intrinsic limitations of computer simulations like finite time and finite size problems do not hamper this analysis. We discuss how the DWP are embedded in the total potential energy landscape. It turns out that most DWP are connected to the dynamics of the smaller particles and that these DWP are rather localized. However, DWP related to the larger particles are more collective.

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• Vibrational density of states and specific heat in glasses from random matrix theory
• The Origin of the Decoupling of Oxygen and Silicon Dynamics in Liquid Silica as Expressed by its Potential Energy Landscape
• Anharmonic properties of vibrational excitations in amorphous solids
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• Quantum Jamming: Critical Properties of a Quantum Mechanical Perceptron
• Intermittent rearrangements accompanying thermal fluctuations distinguish glasses from crystals
• Low temperature breakdown of coherent tunneling in amorphous solids induced by the nuclear quadrupole interaction