# MD

## Calculation of Elastic Modulus of Graphene in LAMMPS

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Hello everyone, I want to calculate elastic constants (C11, C22, C12, and C66) for a single layer graphene sheet by MD simulation in LAMMPS. I am using the following equation:

E = (C11*C22-C12*C21)/C22 and poisson ratio = C12/C22 from this paper:

## Post-Doc Position: Colloids in polymer systems: Numerical studies and simulations

Post-Doc Position: Colloids in polymer systems: Numerical studies and simulations

The Material and Process Simulation group at the University of Bayreuth is offering a

1 Post-Doc Position TV-L E13 (m/f)

Colloids in polymer systems: Numerical studies and simulations

## high strain rate in MD simulations

Dear All,

Recently I have read some literatures on Molecular simulation of polymer. My interest is measurement of

mechanical properties of polymer through the uniaxial tensile test.

I have a question about relatively large time scales in MD simulations of polymer and how to interpret MD

stress-strain results for FE modeling. In particular, in the literature it is mentioned that strain rate of

## GROMACS: Fast, Free and Flexible MD

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GROMACS is a versatile package to perform molecular dynamics, i.e. simulate
the Newtonian equations of motion for systems with hundreds to millions of
particles.

## Equivalence of Virial stress to Continuum Cauchy Stress

Calculating stresses in MD simulations is a controversial topic. There are two different schools of thought about the equivalence of the virial stress to the continuum Cauchy stress; for and against. Some argue based on momentum balance, that only the potential contribution to the virial stress should be considered as the continuum Cauchy stress. However, others assert that the total virial stress that contains both the kinetic and potential parts is indeed the quantity that corresponds to the Cauchy stress in continuum mechanics. We used a simple thermo-elastic analysis to verify the validity of using the total virial stress as the continuum Cauchy stress and found that the total virial stress is indeed the continuum Cauchy stress. 