Landscape equivalent of the shoving model

Area of Science:

• Rheology
• Condensed Matter Physics
• Materials Science

Background:

• The shoving model provides an expression for the average relaxation time of viscous liquids.
• This model posits a direct proportionality between activation energy and instantaneous shear modulus.
• Classical energy landscape estimations often determine barrier heights from the curvature at energy minima.

Purpose of the Study:

• To investigate the theoretical underpinnings of the shoving model for viscous liquids.
• To determine the contribution of bulk and shear moduli to the activation energy within this model.
• To elucidate the relationship between the shoving model and classical energy landscape theories.

Main Methods:

• Theoretical analysis of the shoving model expression for average relaxation time.
• Examination of the relationship between activation energy and instantaneous elastic moduli (bulk and shear).
• Comparison of the shoving model's predictions with classical energy landscape estimations of barrier heights.

Main Results:

• The shoving model's expression for average relaxation time is largely derivable from classical energy landscape estimations.
• Activation energy in this context depends on both instantaneous bulk and shear moduli.
• The bulk modulus accounts for less than 8% of the temperature dependence of the activation energy.

Conclusions:

• The physics described by the shoving model and classical energy landscape estimations are closely related.
• Shear modulus plays a dominant role in the temperature dependence of activation energy within the shoving model.
• The shoving model offers a valuable framework for understanding the dynamics of viscous liquids.