Lennard Jones- reduced units

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SUMMARY

This discussion focuses on the application of the Lennard-Jones (LJ) potential in molecular dynamics (MD) simulations, specifically using argon parameters (epsilon and sigma) to derive thermodynamic quantities for other substances. The law of corresponding states allows for the comparison of properties across different substances at varying temperatures and densities. However, it is crucial to note that each simulation corresponds to a specific state defined by temperature and density, and results cannot be directly extrapolated to other states without running separate simulations.

PREREQUISITES
  • Understanding of Lennard-Jones potential parameters (epsilon and sigma)
  • Knowledge of molecular dynamics simulation techniques
  • Familiarity with thermodynamic properties and their calculations
  • Concept of the law of corresponding states in thermodynamics
NEXT STEPS
  • Explore the implementation of Lennard-Jones potential in MD simulations using software like LAMMPS
  • Learn about the law of corresponding states and its applications in thermodynamics
  • Investigate the effects of temperature and density on thermodynamic properties in MD simulations
  • Study the differences in LJ parameters for various substances and their implications in simulations
USEFUL FOR

This discussion is beneficial for researchers and practitioners in computational chemistry, molecular dynamics simulation, and thermodynamics, particularly those working with Lennard-Jones potentials and seeking to optimize simulations across different substances.

ronbenin
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Hi friends,
I have a question regarding MD simulation using a LJ potential. If I take the e and sigma parameters in the LJ potential to be that corresponding to argon, and calculate some thermodynamic
quantity can I convert the value of that thermodynamic quantity corresponding to some other substance
which might have a different e and sigma. This is because in MD simulation we use reduced units and there is something called the law of corresponding states which might enable one to convert that thermodynamic quantity for another substance without having to run a different simulation.

Please help.

Thanks,
Ronald
 
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Let's say that at certain temperature and density (T1, rho1)you calculate certain quantities for Ar. Then these quantities also belong to Xe at another temperatue and density (T2,rho2) and also belong to Kr at third T,rho and for all other materials decribed by Lennard Jones at Different T,rho.
However, keep in mind that one simulation is equivalent to one state defined by T,rho. There is no direct way to extrapolate the results of one simulation to other states.
 
Hi,
thanks a lot for your help.

Ronald
 

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