What is moving in silica at 1 K? A computer study of the low-temperature anomalies

TL;DR

This study uses computer simulations to investigate the properties of two-level systems in silica at 1 K, providing detailed insights into their energy scales, number, and real-space configurations, and comparing findings with experiments.

Contribution

It introduces a systematic simulation approach to characterize two-level systems in silica, revealing their properties and real-space structures at low temperatures.

Findings

Identified relevant energy scales of TLS in silica.

Estimated the absolute number of TLS in the system.

Provided insights into the real-space realization of TLS.

Abstract

Though the existence of two-level systems (TLS) is widely accepted to explain low temperature anomalies in many physical observables, knowledge about their properties is very rare. For silica which is one of the prototype glass-forming systems we elucidate the properties of the TLS via computer simulations by applying a systematic search algorithm. We get specific information in the configuration space, i.e. about relevant energy scales, the absolute number of TLS and electric dipole moments. Furthermore important insight about the real-space realization of the TLS can be obtained. Comparison with experimental observations is included.