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LAMMPS : Special mechanical properties of Polymers – Elastic properties

Viewed : 193 times,  2021-09-15 02:21:30

Materials exhibit various physical behaviors when external stress is applied. Among such mechanical properties, elasticity refers to the capacity of the material to recover its original shape when the applied force is removed.  Rubber materials in particular have significantly high elasticity.

For further theoretical  details about the mechanical behaviour of polymers, please refer to the Mechanical Properties of Polymers document.

Elasticity is a temperature-dependent property. We can  define this property  in terms ofthe ‘Bulk modulus,’ ‘Shear modulus,’ ‘Young’s modulus,’ and ‘Poisson’s ratio of the material under consideration. The moduli can be measured from the temperature and volume change, and the ‘Poisson’s ratio’ can be obtained from the relation between the temperature and strain.


In this module tip, we’ll learn about the elasticity of  polymer systems using the LAMMPS (Elastic properties) module.



Calculation Procedure

We need the successfully finished ‘LAMMPS (Tg/CTE)’ module to start the elasticity simulation.

You can perform the glass transition temperature (Tg) calculation by referring to the following posts.

  1. Modeling: How to perform the polymer simulation – Polymer MD Modeling
  2. Structure optimization (Thermalization): The Essential Step for Polymer Simulation – Thermalization
  3. Glass transition temperature: The Property of Polymers - Glass Transition Temperature


The initial property of the LAMMPS (Elastic properties) module is set according to the temperature range of the connected ‘LAMMPS (Tg/CTE)’ module. Since  elasticity is hard to check from the melted polymer, it is recommended to set the temperature range lower than Tg when performing the Tg calculation.

In this example,  we used the Tg calculation result from 300~200 K to perform the elastic properties calculation.



Calculation Results


👉View the example work

You can check the obtained Bulk modulus, Shear modulus, Young’s modulus, and Poisson’s ratio results after finishing the calculation.



Example Video



🍀 Need more Information?

[Modules] Molecule Builder

[MatSQ Tip] Molecule Modeling in Materials Square
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[MatSQ Tip] How to Model Polymer in 3D: Molecule Builder
[MatSQ Tip] PolymRize: Predict polymer properties
LAMMPS : Molecular Dynamics Simulation for Polymer – Polymer MD
LAMMPS: How to perform the polymer simulation – Polymer MD Modeling
LAMMPS: The Essential Step for Polymer Simulation – Thermalization
LAMMPS: The Property of Polymer - Glass Transition Temperature